Who is the manufacturer of eQUANT System?

Avails Medical, Inc. filed the 510(k) submission for eQUANT System (K231536).

What is the FDA product code for eQUANT System?

QZX. It is classified under 21 CFR 866.1650 as a Class 2 device in the Microbiology panel.

What is the regulatory pathway for eQUANT System?

510(k) clearance (submission type: Traditional).

What are the predicate devices for eQUANT System?

Accelerate Pheno System, Accelerate PhenoTest BC Kit (K192665).

Who can help prepare an FDA 510(k) submission like eQUANT System?

Innolitics — a medical-device software consultancy — provides regulatory and engineering support for FDA 510(k) submissions. See https://innolitics.com/services/510ks/ or contact https://innolitics.com/contact.

eQUANT System

K231536 · Avails Medical, Inc. · QZX · Feb 8, 2024 · Microbiology

Device Facts

Record ID	K231536
Device Name	eQUANT System
Applicant	Avails Medical, Inc.
Product Code	QZX · Microbiology
Decision Date	Feb 8, 2024
Decision	SESE
Submission Type	Traditional
Regulation	21 CFR 866.1650
Device Class	Class 2

Intended Use

The eQUANT™ System is an automated inoculum preparation system that uses potentiometric sensing of oxidation-reduction potential changes due to pathogen metabolism to generate a 0.5 McFarland-equivalent suspension (the eMcFarland or eMcF) from positive blood culture samples. Samples are processed directly from blood culture samples identified as positive by a continuous monitoring blood culture system and confirmed as Gram-negative rods by Gram stain. Organism identification, as determined by an FDA cleared device for direct testing from positive blood culture, must be available before processing samples on the eQUANT™ System.

Device Story

The eQUANT System automates inoculum preparation for antimicrobial susceptibility testing (AST). It accepts 34 µL of positive blood culture (confirmed Gram-negative rods) added to an eTube containing 1 mL of cation-adjusted Mueller Hinton broth (CAMHB) with antifoam. The system uses a potentiometric sensor (ORP) to monitor pathogen metabolism in real-time at 37°C. As bacteria grow, the medium reduces, causing the voltage to become more negative. An algorithm determines when the concentration reaches a 0.5 McFarland equivalent (eMcF). Once reached, the system cools the sample to 15°C to inhibit further growth. The resulting suspension is used by laboratory technicians for Kirby-Bauer disk diffusion AST. This process eliminates the need for overnight subculturing, potentially accelerating clinical decision-making for antibiotic therapy.

Clinical Evidence

Performance evaluated via method comparison study (567 samples: 42 fresh, 515 contrived, 10 challenge) comparing eQUANT-prepared inocula to standard colony-based inocula using Kirby-Bauer disk diffusion. Primary endpoint was categorical agreement (CA) between methods. Overall CA was generally ≥95%. Specific drug/organism combinations with CA 90-95% were deemed acceptable based on minor error analysis (≤3 mm zone diameter difference). Limitations and footnotes were established for combinations with higher error rates or trending toward smaller zone diameters.

Technological Characteristics

System components: eQUANT instrument, single-use eTube, eQUANT Reagent (CAMHB + 0.0015% antifoam), workflow tray. Sensing: Potentiometric ORP sensor (two electrodes). Energy: Thermal module (37°C growth, 15°C hold). Connectivity: Standalone instrument with touchscreen UI. Software: Version 1.21.0, rule-based algorithm using real-time voltage measurements. Sterilization: Not applicable (disposables).

Indications for Use

Indicated for automated inoculum preparation from monomicrobial positive blood cultures (Gram-negative rods) to generate a 0.5 McFarland-equivalent suspension for direct, qualitative in vitro susceptibility testing via agar disk diffusion (Kirby-Bauer). Indicated for Enterobacterales, Acinetobacter spp., and Pseudomonas aeruginosa. Contraindicated for polymicrobial samples, non-indicated organisms, and specific anaerobic bottle/organism combinations (P. aeruginosa/Acinetobacter spp. from anaerobic bottles).

Regulatory Classification

Identification

A cellular analysis system for multiplexed antimicrobial susceptibility testing is a multiplex qualitative and/or quantitative in vitro diagnostic device intended for the identification and determination of the antimicrobial susceptibility results of organisms detected in samples from patients with suspected microbial infections. This device is intended to aid in the determination of antimicrobial susceptibility or resistance when used in conjunction with other laboratory findings.

Special Controls

*Classification.* Class II (special controls). The special controls for this device are:(1) Design verification and validation must include: (i) Detailed device description documentation, including the device components, ancillary reagents required but not provided, a detailed explanation of the methodology, including primer/probe sequence, design, rationale for sequence selection, and details of the antimicrobial agents, as applicable. (ii) Detailed documentation from the following analytical and clinical performance studies: limit of detection, inclusivity, precision, reproducibility, interference, cross-reactivity, carryover, and cross-contamination, quality control and additional studies, as applicable to specimen type and assay intended use. (iii) Detailed documentation from an appropriate clinical study. The study, performed on a study population consistent with the intended use population, must compare the device performance to results obtained from well-accepted reference methods. (iv) Detailed documentation for device software, including software applications and hardware-based devices that incorporate software. (2) The labeling required under § 809.10(b) of this chapter must include: (i) Limitations and protocols regarding the need for correlation of results by standard laboratory procedures, as applicable. (ii) A detailed explanation of the interpretation of results and acceptance criteria. (iii) A detailed explanation of the principles of operation and procedures for assay performance and troubleshooting.

Predicate Devices

Accelerate Pheno System, Accelerate PhenoTest BC Kit (K192665)

Submission Summary (Full Text)

{0} FDA U.S. FOOD & DRUG ADMINISTRATION # 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY ASSAY AND INSTRUMENT ## I Background Information: A 510(k) Number K231536 B Applicant Avails Medical, Inc. C Proprietary and Established Names eQUANT System D Regulatory Information | Product Code(s) | Classification | Regulation Section | Panel | | --- | --- | --- | --- | | QZX | Class II | 21 CFR 866.1650 - A Cellular Analysis System For Multiplexed Antimicrobial Susceptibility Testing | MI - Microbiology | | JTN | Class II | 21 CFR 866.1620 - Antimicrobial susceptibility test disc | MI - Microbiology | | | | | | ## II Submission/Device Overview: ### A Purpose for Submission: To obtain a substantial equivalence determination for the preparation of a 0.5 McFarland Standard equivalent from positive blood culture samples using the eQUANT System for downstream susceptibility testing with the agar disk diffusion method (Kirby-Bauer). ### B Measurand: Standardized suspension of Gram negative bacteria equivalent to a 0.5 McFarland standard prepared from positive blood culture samples. Food and Drug Administration 10903 New Hampshire Avenue Silver Spring, MD 20993-0002 www.fda.gov {1} K231536 - Page 2 of 31 C Type of Test: Positive blood culture processor that prepares an inoculum for antimicrobial susceptibility testing. III Intended Use/Indications for Use: A Intended Use(s): The eQUANT System is an automated inoculum preparation system that uses potentiometric sensing of oxidation-reduction potential changes due to pathogen metabolism to generate a 0.5 McFarland-equivalent suspension (the eMcFarland or eMcF) from positive blood culture samples. Samples are processed directly from blood culture samples identified as positive by a continuous monitoring blood culture system and confirmed as Gram-negative rods by Gram stain. Organism identification, as determined by an FDA cleared device for direct testing from positive blood culture, must be available before processing samples on the eQUANT System. B Indication(s) for Use: The eQUANT System is an automated inoculum preparation system that uses potentiometric sensing of oxidation-reduction potential changes due to pathogen metabolism to generate a 0.5 McFarland-equivalent suspension (the eMcFarland or eMcF) from positive blood culture samples that can be used for direct, qualitative in vitro susceptibility testing by the agar disk diffusion test method (Kirby-Bauer). Samples are processed directly from blood culture samples identified as positive by a continuous monitoring blood culture system and confirmed as Gram-negative rods by Gram stain. Organism identification must be confirmed by an FDA cleared device for testing from positive blood culture before processing samples on the eQUANT System. Evaluation of the eQUANT System's inoculum preparation was conducted for use with agar disk diffusion susceptibility testing and performance was demonstrated for the following antimicrobial agents with Enterobacterales species, Acinetobacter species and Pseudomonas aeruginosa as identified below: Amoxicillin/clavulanate- Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis Ampicillin- Escherichia coli Aztreonam- Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens and Pseudomonas aeruginosa Cefazolin- Klebsiella pneumoniae Cefepime- Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa {2} Ceftriaxone- Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens Ertapenem- Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens Gentamicin- Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa Levofloxacin- Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa Meropenem- Acinetobacter spp., Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa Piperacillin/tazobactam- Acinetobacter spp., Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa Tobramycin- Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Serratia marcescens, and Pseudomonas aeruginosa Susceptibility test results are intended to be used in conjunction with other clinical and laboratory findings. Standard laboratory protocols for processing positive blood cultures should be followed to ensure availability of isolates for supplemental testing as needed. Additionally, subculture of positive blood culture is necessary for the susceptibility testing of organisms present in polymicrobial samples, for testing antimicrobial agents and species not indicated for testing with the device, for epidemiologic testing, and for recovery of organisms present in microbial samples. C Special Conditions for Use Statement(s): - Rx - For Prescription Use Only - The eQUANT system should not be used for any clinical specimens other than monomicrobial positive blood cultures containing indicated Gram-negative bacteria. - Polymicrobial samples should not be processed on the eQUANT system. - The use of the eQUANT system does not eliminate the need for subculture of the positive blood culture. - If the subculture (purity) plate indicates the sample is polymicrobial, the AST results should be voided, and susceptibility testing on each isolate using a standard inoculum preparation should be performed. K231536 - Page 3 of 31 {3} - The performance of the eQUANT system has only been evaluated with the following blood culture bottles: - bioMérieux BacT/ALERT FA Plus Aerobic - bioMérieux BacT/ALERT FN Plus Anaerobic - bioMérieux BacT/ALERT SA Standard Aerobic - bioMérieux BacT/ALERT SN Standard Anaerobic - BD BACTEC Plus Aerobic - BD BACTEC Plus Anaerobic - BD BACTEC Standard Aerobic - BD BACTEC Standard Anaerobic - BD BACTEC Lytic Anaerobic - Positive blood cultures must be processed immediately on the eQUANT instrument or within 12 hours of blood culture bottle positivity should delay be unavoidable. - The eMcFarland must be removed from with eQUANT Instrument within one (1) hour of run completion. Do not use an eMcFarland that has been incubating in the eQUANT instrument for longer than one (1) hour. - The eMcFarland must be used within ten (10) minutes after it is removed from the eQUANT Instrument to maintain the appropriate organism concentration. - *Pseudomonas aeruginosa* and *Acinetobacter* spp. isolated from anaerobic blood culture bottles should not be run on the eQUANT Instrument. - High concentrations of hemoglobin (>2 g/dL) and platelets (>900,000 µL) may increase the number of Aeration Blockage Errors observed when testing *Acinetobacter* spp. or *P. aeruginosa*, resulting in aborted eQUANT runs. - Performance of the eMcFarland for use in downstream Disk Diffusion AST has only been established using the antibiotics listed in the Indications for Use. - Qualitative interpretation of susceptibility results should be performed in accordance with the disk manufacturer's instructions. - Disk Diffusion AST zone diameter results generated from an eMcFarland inoculum tend to be smaller when compared to disk diffusion zone diameters results generated from a colony inoculum. If zone diameters fall near the low end of the intermediate breakpoint, consider alternative testing for the following drug/organism combinations: - Amoxacillin/Clavulanate: *Proteus vulgaris* - Aztreonam: *Citrobacter freundii*, *Escherichia coli*, *Proteus mirabilis*, *Proteus vulgaris* - Cefepime: *Escherichia coli*, *Klebsiella aerogenes*, *Proteus mirabilis*, *Proteus vulgaris* - Ceftriaxone: *Escherichia coli*, *Klebsiella aerogenes*, *Proteus mirabilis*, *Proteus vulgaris* - Ertapenem: *Escherichia coli*, *Klebsiella oxytoca*, *Proteus mirabilis*, *Proteus vulgaris*, *Serratia marcescens* - Gentamicin: *Klebsiella aerogenes*, *Proteus vulgaris* K231536 - Page 4 of 31 {4} - Levofloxacin: Klebsiella aerogenes, Klebsiella oxytoca - Meropenem: Proteus mirabilis, Proteus vulgaris, Serratia marcescens - Piperacillin/Tazobactam: Proteus mirabilis, Proteus vulgaris - Tobramycin: Proteus vulgaris - Perform an alternative method of testing prior to reporting results for the following antibiotic/organism combination(s): - Aztreonam: Proteus mirabilis when the disk zone diameter from an eMcFarland inoculum produces a resistant result due to one major error. - Cefazolin: Escherichia coli, Proteus mirabilis - Cefepime: Citrobacter freundii, Klebsiella aerogenes - Cefepime: Proteus mirabilis when the disk zone diameter from an eMcFarland inoculum produces a resistant result due to one major error. - The ability of the eQUANT system to generate an inoculum to detect resistance with the following combinations is unknown because an insufficient number of resistant isolates were encountered at the time of comparative testing: - Aztreonam: Proteus mirabilis, Proteus vulgaris - Cefepime: Citrobacter freundii, Klebsiella aerogenes, Proteus mirabilis - Ceftriaxone: Proteus vulgaris - Ertapenem: Klebsiella oxytoca, Proteus vulgaris - Gentamicin: Klebsiella oxytoca, Citrobacter freundii, Proteus vulgaris, Serratia marcescens - Levofloxacin: Klebsiella oxytoca, Klebsiella aerogenes, Proteus vulgaris, Serratia marcescens - Piperacillin/Tazobactam: Proteus vulgaris - Tobramycin: Klebsiella aerogenes, Proteus vulgaris ## D Special Instrument Requirements: eQUANT Instrument, Software Version 1.21.0 ## IV Device/System Characteristics: ### A Device Description: The eQUANT system is an automated instrument that uses potentiometric sensing of changes in oxidation-reduction potential (ORP) during pathogen metabolism to prepare an organism suspension equivalent to a 0.5 McFarland standard (1-2e8 CFU/ml ± 0.6 log) directly from a positive blood culture. The eQUANT system consists of four components: the eQUANT instrument, a single use eTube disposable, a single use eQUANT Reagent tube (CAMHB with antifoam), and a workflow tray. The eQUANT system processes a single positive blood culture sample at a time. Before processing on the eQUANT instrument, the positive blood culture is confirmed as Gram-negative rods followed by organism identification (ID) using an ID method FDA-cleared for use with positive blood culture. Mixed cultures or organisms identified that are not included in the eQUANT intended use must not be processed on the eQUANT system. Positive blood cultures K231536 - Page 5 of 31 {5} must be processed immediately on the eQUANT instrument or within 12 hours of blood culture bottle positivity should delays be unavoidable. Once the organism ID is determined, $1\mathrm{mL}$ of eQUANT Reagent (cation-adjusted Mueller Hinton broth (CAMHB) supplemented with antifoam $(0.0015\%)$ to reduce air bubble formation) is added to the eTube disposable, followed by the addition of $34~\mu \mathrm{L}$ of the positive blood culture. The eTube disposable with diluted sample is vortexed and then placed in the eQUANT instrument for incubation. Once inserted, the eTube disposable sits in a thermal module which is heated to $37^{\circ}\mathrm{C} \pm 2^{\circ}\mathrm{C}$ to grow the bacteria to a concentration equivalent to a $0.5\mathrm{McFarland}$ (eMcFarland, or eMcF). The eQUANT sensor located in the eTube disposable is an ORP sensor consisting of two electrode components, which both come into direct contact with the diluted positive blood culture sample. The eQUANT ORP sensor responds to changes in the ORP during pathogen growth/metabolism. As the concentration of microorganisms in the sample increases, the growth media becomes reduced, and the voltage measured by the ORP sensor becomes more negative. With the organism ID of the tested sample and the blood culture bottle type as inputs to the system, the algorithm is applied to the real-time voltage measurements to determine the point in time at which the organism concentration reaches a level equivalent to a standard $0.5\mathrm{McFarland}$ . At the endpoint, the sample immediately starts to cool down to $15^{\circ}\mathrm{C} \pm 2^{\circ}\mathrm{C}$ to inhibit further growth. The sample can be held for up to one hour on the instrument, before being used for downstream agar disk diffusion susceptibility testing. The eQUANT System can determine the susceptibility of specific organisms when tested against various antimicrobials (Table 1). Table 1. Organism-Specific Breakpoints for Antimicrobials for use with the eQUANT System | Antimicrobial | Organism Group | FDA-Recognized/Approved Breakpoints* (zone diameter in mm) | | | | --- | --- | --- | --- | --- | | | | S | I | R | | Amoxicillin/Clavulanate | Enterobacterales | ≥ 18 | 14-17 | ≤ 13 | | Ampicillin | Enterobacterales | ≥ 17 | 14-16 | ≤ 13 | | Aztreonam | Enterobacterales | ≥ 21 | 18-20 | ≤ 17 | | | P. aeruginosa | ≥ 22 | 16-21 | ≤ 15 | | Cefazolin | Enterobacterales | ≥ 23 | 20-22 | ≤ 19 | | Cefepime | Enterobacterales | ≥ 25 | 19-24 | ≤ 18 | | | P. aeruginosa | ≥ 18 | - | ≤ 17 | | Ceftriaxone | Enterobacterales | ≥ 23 | 20-22 | ≤ 19 | | Antimicrobial | Organism Group | FDA-Recognized/Approved Breakpoints* (zone diameter in mm) | | | | --- | --- | --- | --- | --- | | | | S | I | R | | Ertapenem | Enterobacterales | ≥ 22 | 19-21 | ≤ 18 | | Gentamicin | Enterobacterales, P. aeruginosa | ≥ 15 | 13-14 | ≤ 12 | | Levofloxacin | Enterobacterales | ≥ 21 | 17-20 | ≤ 16 | | | P. aeruginosa | ≥ 22 | 15-21 | ≤ 14 | K231536 - Page 6 of 31 {6} | Antimicrobial | Organism Group | FDA-Recognized/Approved Breakpoints* (zone diameter in mm) | | | | --- | --- | --- | --- | --- | | | | S | I | R | | Meropenem | Enterobacterales | ≥ 23 | 20-22 | ≤ 19 | | | P. aeruginosa | ≥ 19 | 16-18 | ≤ 15 | | | Acinetobacter spp. | ≥ 18 | 15-17 | ≤ 14 | | Piperacillin/Tazobactam | Enterobacterales | ≥ 25 | 21-24 | ≤ 20 | | | P. aeruginosa | ≥ 21 | 15-20 | ≤ 14 | | | Acinetobacter spp. | ≥ 21 | 18-20 | ≤ 17 | | Tobramycin | Enterobacterales, P. aeruginosa | ≥ 15 | 13-14 | ≤ 12 | * FDA STIC Website https://www.fda.gov/drugs/development-resources/fda-recognized-antimicrobial-susceptibility-test-interpretive-criteria (-) Indicates that a corresponding zone diameter range is not defined for that category. ## B Principle of Operation: See Device Description. ## C Instrument Description Information: 1. Instrument Name: eQUANT Instrument 2. Specimen Identification: Gram stain analysis and identification (ID) using a method FDA-cleared for use with positive blood cultures are performed prior to initiating the eQUANT Instrument. The eQUANT Instrument does not track patient samples internally. Sample traceability is up to the user to label the eQUANT eTube disposable with sample information. A Label Tag area has been provided on all eTube disposables to either write sample information or attach a (LIS) label sticker. This Label Tag is visible even when the eQUANT Instrument lid is closed. The user then selects the organism ID and blood culture bottle type from the dropdown menu on the touchscreen user interface of the eQUANT Instrument. 3. Specimen Sampling and Handling: Positive blood culture (PBC) samples must be processed immediately or within 12 hours of positivity should delays be unavoidable. The user places the eTube disposable and eQUANT Reagent tube in designated slots in the provided workflow tray. PBC bottles are vortexed and the septum of the PBC bottle is sterilized prior to collecting 500 μL using a syringe and transferring to a sterile tube. One mL of the eQUANT Reagent and 34μL of the PBC sample are aliquoted into the eTube disposable and then vortexed. After the user ensures bubbles have been eliminated, the eTube disposable is placed back into the workflow tray. The eTube sample will be loaded into the eQUANT following instrument prompts. K231536 - Page 7 of 31 {7} K231536 - Page 8 of 31 4. Calibration: The eQUANT Instrument is equipped with an internal Quality Control that is automatically performed with each run. Once the eTube disposable with sample (diluted PBC) is inserted into the eQUANT Instrument and the run is started, a series of built-in checks are conducted to ensure that essential Instrument and eTube disposable performance specifications are met enabling the generation of an eMcFarland within the target range of $1 - 2\mathrm{e}8 \pm 0.6$ log CFU/mL. 5. Quality Control: Quality controls are performed to ensure that the eQUANT Instrument and eTube disposable work according to their intended use and performance specifications. The eQUANT Instrument has a validated built-in Quality Control (Internal QC) that is designed to check the eTube disposable and instrument performance parameters during every run that is performed on the instrument. Good laboratory practices recommend performing additional external QC testing to verify appropriate colony counts and acceptable AST results. Colony counts may be QC tested using contrived or clinical positive blood culture samples to confirm results are in the expected range $(2.51 \times 10^{7}$ to $7.96 \times 10^{8} \mathrm{CFU} / \mathrm{mL})$. AST may be QC tested using positive blood culture samples contrived with CLSI-recommended QC strains. Alternatively, AST may be QC tested per the disk manufacturer's instructions. V Substantial Equivalence Information: A Predicate Device Name(s): Accelerate Pheno System, Accelerate PhenoTest BC Kit B Predicate 510(k) Number(s): K192665 C Comparison with Predicate(s): | Device & Predicate Device(s): | Device: K231536 | Predicate: K192665 | | --- | --- | --- | | Device Trade Name | eQUANT System | Accelerate Pheno System, Accelerate PhenoTest BC Kit | | General Device Characteristic Similarities | | | | Intended Use | The eQUANT System is an automated inoculum preparation system that uses potentiometric sensing of oxidation-reduction potential changes due to pathogen metabolism to generate a 0.5 McFarland-equivalent suspension (the eMcFarland or eMcF) from positive blood culture samples. Samples are processed directly from blood culture samples | The Accelerate PhenoTest BC kit is a multiplexed in vitro diagnostic test utilizing both qualitative nucleic acid fluorescence in situ hybridization (FISH) identification and quantitative, antimicrobial susceptibility testing (AST) methods and is intended for use with the Accelerate Pheno system. The Accelerate PhenoTest BC kit is capable of simultaneous detection and identification of multiple microbial targets followed by susceptibility testing of the appropriate detected bacterial | {8} K231536 - Page 9 of 31 | Device & Predicate Device(s): | Device: K231536 | Predicate: K192665 | | --- | --- | --- | | | identified as positive by a continuous monitoring blood culture system and confirmed as Gram-negative rods by Gram stain. Organism identification, as determined by an FDA cleared device for direct testing from positive blood culture, must be available before processing samples on the eQUANT System. | organisms. The Accelerate PhenoTest BC kit is performed directly on blood culture samples identified as positive by a continuous monitoring blood culture system. Results are intended to be interpreted in conjunction with Gram stain results. | | Antibiotics | Amoxicillin/clavulanate Ampicillin Aztreonam Cefazolin Cefepime Ceftriaxone Ertapenem Gentamicin Levofloxacin Meropenem Piperacillin/Tazobactam Tobramycin | Amikacin Ampicillin Ampicillin/Sulbactam Aztreonam Ceftazidime Ceftaroline Cefepime Ceftriaxone Ciprofloxacin Daptomycin Ertapenem Gentamicin Linezolid Meropenem Piperacillin/Tazobactam Tobramycin Vancomycin | | Indicated Organisms | Acinetobacter spp. Citrobacter freundii Enterobacter cloacae Escherichia coli Klebsiella aerogenes Klebsiella pneumoniae Klebsiella oxytoca Proteus mirabilis Proteus vulgaris Pseudomonas aeruginosa Serratia marcescens | Gram-negative species: Acinetobacter baumannii Citrobacter spp. Enterobacter spp. Escherichia coli Klebsiella spp. Proteus spp. Pseudomonas aeruginosa Serratia marcescens Additional Gram-positive bacteria and yeast are also included on the Accelerate PhenoTest BC kit. | | Sample Type | Positive blood culture aliquot | Same | | **General Device Characteristic Differences** | | | | Technology | Measure pathogen concentration via potentiometric sensing of changes in oxidation-reduction potential (ORP) during pathogen metabolism. Uses species-specific | Microscopy-based, single cell analysis. Identification via fluorescence *in situ* hybridization (FISH); AST via microscopic observation of individual growing bacterial cells in the presence | {9} | Device & Predicate Device(s): | Device: K231536 | Predicate: K192665 | | --- | --- | --- | | | and blood culture bottle specific algorithms to determine when a 0.5 McFarland equivalent concentration is reached. | of antimicrobial agents. | | Output/Results Reporting | Liquid suspension of bacterial (0.5 McFarland equivalent) suitable for Disk Diffusion susceptibility testing; no results reported | Microbial identification and MIC-based susceptibility test results | VI Standards/Guidance Documents Referenced: - FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA (Issued August 28, 2009) - CLSI M100-Ed33. Performance Standards for Antimicrobial Susceptibility Testing; 33rd Edition (March 2023) - CLSI. Performance Standards for Antimicrobial Disk Susceptibility Tests. 13th ed. CLSI standard M02, Edition 13. Clinical and Laboratory Standards Institute; 2018. VII Performance Characteristics (if/when applicable): A Analytical Performance: 1. Precision/Reproducibility: The Reproducibility Study was performed to demonstrate that the eQUANT System reproducibly prepares an 0.5 McFarland equivalent inoculum, the eMcFarland, at an organism concentration of $1 \times 10^{8}$ to $2 \times 10^{8} \pm 0.6$ log ($2.51 \times 10^{7}$ to $7.96 \times 10^{8}$) CFU/mL from a positive blood culture (PBC). The reproducibility of the eQUANT System was assessed across sites (one internal and two external), with six operators, six runs, 12 instruments and consumable lots. A panel of six organisms was contrived in blood culture bottles with human blood added and incubated on a blood culture monitoring system until positivity. From each positive blood culture, initial eQUANT System testing was performed in duplicate by two operators at each site for a total of four eMcFarlands per PBC. The resulting eMcFarlands were plated to confirm that colony counts met the defined concentration specifications. Reproducibility for all species was acceptable ($\geq 95\%$) except for $A$. baumannii. Overall colony counts of $A$. baumannii were $< 95\%$ in-range in the initial study ($67/72 = 93.1\%$) and were further evaluated in a supplemental in-house study in which testing was performed with three instruments and two operators for five days (1 site x 5 days x 1 organism x 3 replicates x 2 operators = 30 eQUANT runs). Data from both studies are collated and summarized in Table 2. Performance is summarized for each species tested. Overall reproducibility of the eQUANT System was $>95\%$ in-range colony counts and determined to be acceptable. K231536 - Page 10 of 31 {10} Table 2. eQUANT System Reproducibility Results Summary | Organism | In-Range Test Results | Reproducibility % | | --- | --- | --- | | Escherichia coli | 72/72 | 100.0 | | Pseudomonas aeruginosa | 72/72 | 100.0 | | Acinetobacter baumannii | 97/102 | 95.1 | | Proteus vulgaris | 72/72 | 100.0 | | Serratia marcescens | 72/72 | 100.0 | | Overall Agreement | 457/462 | 98.9 | 2. Linearity: Not applicable. 3. Analytical Specificity/Interference: Endogenous/Exogenous Interfering Substances An interfering substances study was performed to evaluate if substances naturally present or artificially introduced into blood culture bottles affect the eQUANT System performance. A panel of nine different bacterial isolates (four isolates of *A. baumannii*, two isolates of *E. coli* and one isolate each of *K. pneumoniae*, *P. vulgaris*, and *P. aeruginosa*) were individually mixed with human whole blood, seeded directly into a BacT/ALERT SA Standard Aerobic blood culture bottle and incubated for growth in a continuous monitoring blood culture system until indicated as positive for growth (i.e., bottle ring). Each potential interfering substance (Table 3), and individual antibiotics from each drug class (Table 4), were tested at the concentrations listed below. Each test isolate had one control bottle replicate without the interferent added and three test bottle replicates with the interferent added at appropriate concentrations according to the test procedure. For blood culture bottles containing interferents that could not achieve a high concentration (positivity), the organism was grown to positivity without the interferent, and the interferent was spiked directly into the eTube. When acceptance criteria were not met, repeat testing was performed in triplicate. Colony counts and Kirby-Bauer disk diffusion with indicated antimicrobials were performed for all indicated species. Expected AST results (>95% overall CA) were obtained for all organism samples containing endogenous and exogenous interfering substances tested; all categorical errors were minor and less than 3 mm difference when compared to the control replicate (i.e., no potential interferent) AST results (Table 3). However, high concentrations of two substances, hemoglobin (*A. baumannii*, *P. aeruginosa*) and platelets (*P. aeruginosa*), resulted in aborted eQUANT Instrument runs due to aeration blockage errors detected by the instrument. At decreased interferent concentration, valid eMcFarlands were successfully generated and AST results were as expected. The following limitation is included in the device labeling, High concentrations of hemoglobin (>2 g/dL) and platelets (>900,000 µL) may increase the number of Aeration Blockage Errors observed when testing Acinetobacter spp. or *P. aeruginosa*, resulting in aborted eQUANT runs. In addition, 100% of all colony counts were within the expected range of 1×10⁸ to 2×10⁸ ± 0.6 log (2.51×10⁷ to 7.96×10⁸) CFU/mL. K231536 - Page 11 of 31 {11} Table 3. Endogenous and Exogenous Interfering Substances Study AST Results | Substance | Concentration | Enterobacterales | | P. aeruginosa | | A. baumannii | | | --- | --- | --- | --- | --- | --- | --- | --- | | | | No. CA/ Totala | % CA | No. CA/ Totalb | % CA | No. CA/ Totalc | % CA | | Hemoglobin* | 20 g/dL 2 g/dL – 8 g/dLg | 130/132 | 98.5 | 21/21 | 100.0 | 23/24 | 95.8 | | SPS | 0.1% w/v | 132/132 | 100.0 | 20/21 | 95.2 | 24/24 | 100.0 | | Heparin | 3 units/mL | 129/132 | 97.8 | 21/21 | 100.0 | 24/24 | 100.0 | | Triglyceride | 37 mmol/L | 129/132 | 97.8 | 21/21 | 100.0 | 23/24 | 95.8 | | Platelets | 1e6/μL 9e5/ μL (P. aeruginosa) | 132/132 | 100.0 | 21/21 | 100.0 | 24/24 | 100.0 | | WBCs (Buffy Coat)* | 12,000/μL | 132/132 | 100.0 | 21/21 | 100.0 | 24/24 | 100.0 | | Hematocrit* | 50% | 129/132 | 97.8 | 21/21 | 100.0 | 24/24 | 100.0 | | Conj. Bilirubin | 40 mg/dL | 128/132 | 97.0 | 21/21 | 100.0 | 24/24 | 100.0 | | Gamma-Globulin* | 50 mg/mL | 132/132 | 100.0 | 21/21 | 100.0 | 24/24 | 100.0 | | Unconjug. Bilirubin | 40 mg/dL | 129/132 | 97.8 | 21/21 | 100.0 | 24/24 | 100.0 | CA – categorical agreement ${}^{a}$ Disk diffusion results from amoxicillin/clavulanic acid,ampicillin,aztreonam,cefazolin,cefepime, ceftriaxone, ertapenem, gentamicin,levofloxacin,meropenem,piperacillin/tazobactam,and tobramycin ${}^{\mathrm{b}}$ Disk diffusion results from aztreonam,cefepime,gentamicin,levofloxacin,meropenem,piperacillin/tazobactam and tobramycin Meropenem and piperacillin/tazobactam disk diffusion results *Endogenous substances added directly into the eTube as acceptable organism concentrations in the blood culture bottle were not achieved. Concentration assessed for A. baumannii and P. aeruginosa In a limited study with four resistant isolates, expected AST results ( $>95\%$ overall CA) were obtained for all antibiotic interfering substances tested except for $A.$ baumannii in the presence of chloramphenicol $(2.41\mathrm{e}2\mu \mathrm{mol} / \mathrm{L})$ with a CA of $75\%$ (9/12). Since all three categorical errors were minor with all zone diameter errors having a one mm difference when compared to the control replicate zone diameter result, performance was considered acceptable. Table 4. Antibiotic Interfering Substances Study AST Results | Substance | Concentration | Enterobacterales | | P. aeruginosa | | A. baumannii d | | | --- | --- | --- | --- | --- | --- | --- | --- | | | | No. CA/ Total | % CA | No. CA/ Total | % CA | No. CA/ Total | % CA | | Ampicillin | 2.15e2 μmol/L | 60/63a | 95.2 | NA | NA | NA | NA | | Ceftriaxone | 1.51e3 μmol/L | 36/36b | 100.0 | NA | NA | NA | NA | | Cefazolin | 2.643 mmol/L | 33/33c | 100.0 | NA | NA | NA | NA | | Chloramphenicol | 2.41e2 μmol/L | NA | NA | 21/21 | 100.0 | 9/12 | 75.0* | | Ciprofloxacin | 3.62 μmol/L | 36/36b | 100.0 | NA | NA | NA | NA | | Gentamicin | 6.28 μmol/L | NA | NA | NA | NA | 6/6 | 100.0 | | Cefepime | 492 μg/mL | 36/36b | 100.0 | NA | NA | NA | NA | | Trimethoprim/ Sulfamethoxazole | 1.4e-4 M/ 1.5e-3 M | 33/33c | 100.0 | NA | NA | NA | NA | | Tetracycline | 5.40 μmol/L | NA | NA | 21/21 | 100.0 | 6/6 | 100.0 | | Piperacillin/ Tazobactam | 2.13 μmol/L/ 1.02e2 μmol/L | 36/36b | 100.0 | NA | NA | NA | NA | CA, categorical agreement; NA, Not applicable. K231536 - Page 12 of 31 {12} $^{a}$ E. coli, one isolate; P. vulgaris, one isolate $^{b}$ E. coli, one isolate $^{c}$ K. pneumoniae, one isolate $^{d}$ A. baumannii, one isolate was assessed for each antibiotic except for chloramphenicol, which tested two isolates *Acceptable performance since 3/3 minor errors were ≤ 3mm difference in zone diameter when compared to the control replicate (i.e., no potential interferent). # 4. Assay Reportable Range: Not applicable. # 5. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods): Quality Control Testing. Quality control testing was performed each day that testing was conducted. CLSI recommended QC strains for each antimicrobial were tested a sufficient number of times (i.e., at least 20 times/site) at each testing site using the eQUANT System. Quality Control testing was performed using contrived positive blood cultures spiked with one of three CLSI recommended QC strains (E. coli ATCC 25922, K. pneumoniae ATCC 700603, and P. aeruginosa ATCC 27853), covering each of the antimicrobials tested. QC with at least one strain was performed on each day of testing at each site on a rotating basis. QC acceptance criteria was based on eQUANT eMcFarland colony counts and on expected Disk Diffusion AST results. For the eMcFarland concentration, QC pass rates were based on eMcFarland colony counts within the expected range of 2.51e7 and 7.96e8 CFU/mL. If outside the expected range, QC was repeated. Overall, eMcFarland colony counts were within the expected colony range for $99.2\%$ of samples, with $98.8\%$ in-range for E. coli ATCC 25922, $100\%$ in-range for K. pneumoniae ATCC 700603, and $98.9\%$ in-range for P. aeruginosa ATCC 27853. QC sample eMcFarlands were also tested using the panel of Disk Diffusion antimicrobials indicated with the QC strain being tested. QC expected ranges and results for the eQUANT System are summarized in Table 5. For all antimicrobials, except for meropenem, greater than $95\%$ of results were within the expected range, which is acceptable. Eight of the $P.$ aeruginosa ATCC 27853 QC failures with meropenem occurred at Site 2 and were due to a suspected defective set of meropenem antimicrobial disks. The disks were replaced, and meropenem QC at this site subsequently passed. Sample meropenem Disk Diffusion results impacted by the Meropenem QC failures were excluded from performance analysis. Table 5. QC Expected Ranges and Results for the eQUANT System | Antimicrobial | QC Organism | Expected Range (mm) | No. in Range (%) | | --- | --- | --- | --- | | | | | eQUANT | | Amoxicillin/Clavulanic Acid | E. coli ATCC 25922 | 18-24 | 79/79 (100) | | Ampicillin | E. coli ATCC 25922 | 15-22 | 80/80 (100) | | Aztreonam | E. coli ATCC 25922 | 28-36 | 80/80 (100) | | | K. pneumoniae ATCC 700603 | 10-16 | 82/82 (100) | | | P. aeruginosa ATCC 27853 | 23-29 | 88/88 (100) | | Cefazolin | E. coli ATCC 25922 | 21-27 | 79/80 (98.8) | | Cefepime | E. coli ATCC 25922 | 31-37 | 79/80 (98.8) | | | K. pneumoniae ATCC 700603 | 23-29 | 80/81 (98.8) | | | P. aeruginosa ATCC 27853 | 25-31 | 90/90 (100) | | Ceftriaxone | E. coli ATCC 25922 | 29-35 | 80/80 (100) | K231536 - Page 13 of 31 {13} | Antimicrobial | QC Organism | Expected Range (mm) | No. in Range (%) | | --- | --- | --- | --- | | | | | eQUANT | | | K. pneumoniae ATCC 700603 | 16-24 | 81/82 (98.8) | | | P. aeruginosa ATCC 27853 | 17-23 | 89/90 (98.9) | | Ertapenem | E. coli ATCC 25922 | 29-36 | 80/80 (100) | | | P. aeruginosa ATCC 27853 | 13-21 | 86/88 (97.7) | | Gentamicin | E. coli ATCC 25922 | 19-26 | 80/80 (100) | | | P. aeruginosa ATCC 27853 | 17-23 | 88/88 (100) | | Levofloxacin | E. coli ATCC 25922 | 29-37 | 80/80 (100) | | | P. aeruginosa ATCC 27853 | 19-26 | 88/88 (100) | | Meropenem | E. coli ATCC 25922 | 28-35 | 80/80 (100) | | | P. aeruginosa ATCC 27853 | 27-33 | 76/88 (86.4)* | | Piperacillin/Tazobactam | E. coli ATCC 25922 | 24-30 | 80/80 (100) | | | P. aeruginosa ATCC 27853 | 25-33 | 87/88 (98.9) | | Tobramycin | E. coli ATCC 25922 | 18-26 | 80/80 (100) | | | P. aeruginosa ATCC 27853 | 20-26 | 162/162 (100) | *8/12 QC failures with P. aeruginosa ATCC 27853 were due to a defective set of meropenem disks. Any PBC clinical samples tested on those days were excluded from the final analysis. Device Failure. The eQUANT Instrument is equipped with a self-checking mechanism to identify run errors. There were six instrument aborted runs (6/578 = 1.0%) that were observed in the original and supplemental clinical studies. All were detected at the time of failure by the instrument and resulted in excluded samples, and samples were repeated per device labeling. Three aborted runs were due to aeration blockage detection, two aborted runs were due to exceeding maximum eQUANT runtime, and one aborted run was due to an ORP signal error detected. Four of the six runs resolved upon repeat testing. No additional follow-up or instrument changes were performed. 6. Detection Limit: Not applicable. 7. Assay Cut-Off: Not applicable. 8. Accuracy (Instrument): Not applicable. 9. Carry-Over: A Carryover Study was performed to evaluate if bacterial carryover occurs between runs on the eQUANT System. Two organisms with distinct colony morphologies, E. coli and P. aeruginosa, were individually mixed into human whole blood, seeded directly into a BacT/ALERT SA Standard Aerobic blood culture bottle and incubated for growth in a continuous monitoring blood culture system until indicated as positive for growth (i.e., bottle ring). The resulting PBC samples were run on the same eQUANT System within 12 hours of positivity in an alternating pattern for a total of three (3) runs per species. The resulting eMcFarlands were subcultured to assess whether carryover occurred between runs. All colony counts were within the expected range (2.51e7 to 7.96e8 CFU/mL). No carryover was observed, as evidenced by monomicrobial cultures of the expected organism, which was acceptable. K231536 - Page 14 of 31 {14} # B Comparison Studies: 1. Method Comparison with Predicate Device: The purpose of the method comparison study was to demonstrate the clinical performance of the eQUANT System in providing in-range colony counts equivalent to a 0.5 McFarland (2.51e7 to 7.96e8 CFU/mL) and qualitative disk diffusion (DD) AST results direct from positive blood culture (PBC) containing Gram-negative bacteria. AST DD results obtained with inoculum prepared with the eQUANT System were compared to DD results obtained with inoculum prepared from isolated colonies (i.e., standard), according to CLSI M02. Positive blood cultures included fresh, leftover samples from patients with suspected bacteremia along with positive blood cultures contrived with clinical stock isolates from the clinical sites or challenge isolates. Clinical stock isolates and challenge isolates were enrolled to supplement fresh positive blood cultures due to low prevalence of certain species and antimicrobial resistance expected during prospective collection. Isolates were subcultured on appropriate media (Tryptic Soy Agar with 5% sheep blood), spiked into blood culture bottles at a concentration of approximately 10² CFU per bottle containing fresh human donor blood, and incubated on the appropriate blood culture system until indicated as positive for growth (i.e., bottle ring). Testing with the eQUANT System was performed within 12 hours of blood culture positivity with approximately 53% of PBC samples tested within four hours of flagging positive, 28% of samples tested within 4-8 hours of positivity, and the remaining 19% of samples tested within 8-12 hours of positivity. Organism identification obtained from an FDA-cleared identification method was required input into the eQUANT System. An aliquot from all positive blood cultures was subcultured onto Tryptic Soy Agar with 5% Sheep Blood and incubated for 18-24 hours to check for purity and for comparator testing by standard disk diffusion, per CLSI guidelines. Since the PBC sample type is different from the sample type evaluated to support FDA-clearance for disk diffusion and testing direct from PBC presents additional risks, clinical studies were performed to evaluate and support individual antimicrobial/organism claims. Clinical performance testing on the eQUANT System was initially performed at three U.S. test sites (2 external, 1 internal). For instances in which additional testing was required to supplement existing data from the original study and support specific claims, testing was performed at one internal site. In the original clinical study, a total of 165 positive blood culture samples (PBCs) were enrolled with 155 included in performance analysis. Of the 155 PBCs, 42 were fresh, prospective samples (27.1%), 103 were contrived with stock isolates (66.5%) and 10 were contrived with challenge isolates (6.5%). In the supplemental study, a total of 413 PBC samples contrived from stock isolates were enrolled with 412 PBC samples included in performance analysis. A total of 578 samples were enrolled in the original and supplemental study, which included fresh, prospective PBC and contrived PBC spiked with either clinical stock or challenge isolates. Eleven samples were excluded due to off-panel organisms, polymicrobial samples, insufficient growth, sample mix-up, and protocol deviations. In total, 567 samples were included in the performance analysis including 42 fresh, positive blood K231536 - Page 15 of 31 {15} cultures, 515 contrived blood cultures with clinical stock isolates and 10 contrived blood cultures with challenge isolates. Clinical stock and challenge isolates were collected for testing. In the selection of clinical stock isolates, on-panel organisms (i.e. Gram-negative bacteria species included in the eQUANT System indications for use) available from isolate banks at the external and internal clinical sites were selected to supplement species and antimicrobial resistance recommendations. These isolates were originally sourced from clinical specimens from patients admitted at the clinical site or supplied by the sponsor. Pure isolates were cultured and contrived in blood cultures using healthy human donor blood and tested upon indicated as positive for growth (i.e. bottle ring). A panel of challenge isolates was provided for potential testing at the three original clinical sites; however, the results were only included from one external clinical site. These challenge isolates include well-characterized isolates with known resistance profiles that were obtained from isolate repositories, including the CDC/FDA AR Bank. Disk diffusion performance using eQUANT-prepared inocula was evaluated in comparison to the standard DD. Categorical agreement (CA) was defined as DD interpretation results (S/I/R) that were the same between the eQUANT-prepared and standard-prepared inocula. Very major errors were defined as false susceptible results from the eQUANT-prepared inocula, major errors were defined as false resistance results from the eQUANT-prepared inocula, and minor errors were defined as results with minor discrepancies (i.e. an intermediate result reported as either resistant or susceptible, or vice versa). Since this is a method-to-method comparison, results were considered acceptable if the CA was ≥95% with ≤1% very major errors and ≤1.5% major errors. Drug/organism combinations with CA performance of 90-95% were considered acceptable due to minor errors when the eQUANT zone diameters of a significant number of the errors were ≤3 mm difference compared to the standard disk diffusion zone diameters. A high-level summary of the eQUANT System performance is described below for each antimicrobial and indicated species. Complete details and results including CA and error rate analyses are summarized in Table 6. Amoxicillin/Clavulanic Acid. A total of 223 Enterobacterales isolates (146 Escherichia coli, 15 Klebsiella oxytoca, 21 Klebsiella pneumoniae, and 41 Proteus mirabilis) were evaluated with amoxicillin/clavulanic acid. The combined results from clinical and challenge isolate testing demonstrated a CA of 94.2%. There were 12 minor, 1 major (1/150 = 0.7%) and 0 very major errors. When evaluating results by individual species, E. coli had a CA of 93.8% with 8 minor, 1 major (1/93 = 1.1%) and 0 very major errors. Since the eQUANT zone diameter of 6 of the 8 minor errors were ≤3 mm difference compared to the zone diameter of the standard DD method, the CA performance was considered acceptable and a footnote was included in the device labeling to address the CA performance. P. mirabilis had a CA of 92.7% with 3 minor, 0 major and 0 very major errors. Since the eQUANT zone diameter of 2 of the 3 minor errors were ≤3 mm difference compared to the zone diameter of the standard DD method, the CA performance was considered acceptable and a footnote was included in the device labeling to address the 90-95% CA performance. The following footnote was included in the device labeling to address the 90-95% CA performance when testing amoxicillin/clavulanic acid: K231536 - Page 16 of 31 {16} Categorical agreement was 90-95% due to minor errors for the following drug/organism combinations and considered acceptable since the eQUANT zone diameters of a significant number of the errors were ≤3 mm difference compared to the standard disk diffusion zone diameters: Amoxicillin/Clavulanic acid: Escherichia coli, Proteus mirabilis Ampicillin. A total of 33 E. coli isolates were evaluated with ampicillin. The combined results from prospective and stock isolate testing demonstrated a CA of 100% with no errors. Overall, performance is acceptable. Aztreonam. A total of 189 Enterobacterales isolates (60 E. coli, 22 K. aerogenes, 21 K. pneumoniae, 15 K. oxytoca, 8 E. cloacae, 21 P. mirabilis, 16 P. vulgaris, 13 S. marcescens, 11 C. freundii, and 2 Citrobacter spp.) were evaluated with aztreonam. The combined results from clinical and challenge isolate testing demonstrated a CA of 96.8% with 5 minor, 1 major error (1/141 = 0.7%) and 0 very major errors. When evaluating results by individual species, P. mirabilis had a CA of 95% with 1 major error (1/20 = 5.0%). The following limitation is included in the device labeling to address the high major error rate: - Perform an alternative method of testing prior to reporting results for the following antibiotic/organism combination(s): - Aztreonam: Proteus mirabilis when the disk zone diameter from an eMcFarland inoculum produces a resistant result due to one major error. A limitation statement is included in the device labeling to address the lack of testing with resistant Proteus mirabilis and Proteus vulgaris isolates. A total of 25 P. aeruginosa isolates were evaluated with aztreonam. The combined results from clinical and challenge isolate testing demonstrated a CA of 96% with 1 minor error and 0 major and 0 very major errors. Overall, performance was acceptable. Cefazolin. A total of 213 Enterobacterales isolates (131 E. coli, 41 K. pneumoniae and 41 P. mirabilis isolates) were evaluated with cefazolin. The combined results from clinical and challenge isolate testing demonstrated a CA of 85% with 31 minor errors, 1 major error (1/71 = 1.4%) and 0 very major errors. When evaluating results by individual species, E. coli had a CA of 82.4% with 23 minor, 0 major and 0 very major errors. The performance is not acceptable. P. mirabilis had a CA of 85.4% with 5 minor, 1 major (1/71 = 1.4%), and 0 very major errors. The performance is not acceptable. K. pneumoniae had a CA of 92.7% with three minor, 0 major and 0 very major errors. Since the eQUANT zone diameter of the three minor errors were ≤3 mm difference compared to the zone diameter of the standard DD method, the CA performance was considered acceptable and the following footnote was included in the device labeling to address the 90-95% CA performance: - Categorical agreement was 90-95% due to minor errors for the following drug/organism combinations and considered acceptable since the eQUANT zone diameters of a significant number of the errors were ≤3 mm difference compared to the standard disk diffusion zone diameters: - Cefazolin: Klebsiella pneumoniae K231536 - Page 17 of 31 {17} Due to the unacceptable performance for E. coli and P. mirabilis these drug/organism combinations are not indicated for use with the eQUANT System. The following limitation is included in the device labeling to restrict reporting of E. coli and P. mirabilis due to unacceptable performance: - Perform an alternative method of testing prior to reporting results for the following antibiotic/organism combination(s): - Cefazolin: Escherichia coli, Proteus mirabilis Cefepime. A total of 237 Enterobacterales isolates (40 E. coli, 21 S. marcescens, 21 K. pneumoniae, 15 K. oxytoca, 21 K. aerogenes, 41 E. cloacae, 21 C. freundii, 16 P. vulgaris, and 41 P. mirabilis isolates) were evaluated with cefepime. The combined results from clinical and challenge isolate testing demonstrated a CA of 91.2% with 18 minor errors, 1 major error (1/162 = 0.6%) and 0 very major errors. When evaluating results by individual species, C. freundii had a CA of 81% with 4 minor errors, 0 major and 0 very major errors. The performance was not acceptable. K. aerogenes had a CA of 85.7% with 3 minor errors, 0 major and 0 very major errors. The performance was not acceptable. E. cloacae had a CA of 90.2% with 4 minor errors, 0 major and 0 very major errors. Since the eQUANT zone diameter of 2 of the 4 minor errors were ≤3 mm difference compared to the zone diameter of the standard DD method, the CA performance was considered acceptable and a footnote was included in the device labeling to address the CA performance. K. oxytoca had a CA of 93.3% with one minor error, 0 major and 0 very major errors. Since the eQUANT zone diameter of the minor error was ≤3 mm difference compared to the zone diameter of the standard DD method, the CA performance was considered acceptable and a footnote was included in the device labeling to address the CA performance. P. mirabilis had a CA of 92.7% with 2 minor errors, 1 major error (1/35 = 2.9%), and 0 very major errors. Since the eQUANT zone diameter of 2 of the 4 minor errors were ≤3 mm difference compared to the zone diameter of the standard DD method, the CA performance was considered acceptable and a footnote was included in the device labeling to address the 90-95% CA performance. The following footnote was included in the device labeling to address the 90-95% CA performance when testing cefepime. - Categorical agreement was 90-95% due to minor errors for the following drug/organism combinations and considered acceptable since the eQUANT zone diameters of a significant number of the errors were ≤3 mm difference compared to the standard disk diffusion zone diameters: - Cefepime: Enterobacter cloacae, Klebsiella oxytoca, Proteus mirabilis Due to the unacceptable performance for C. freundii and K. aerogenes, these drug/organism combinations are not indicated for use with the eQUANT System. The following limitation is included in the device labeling to restrict reporting of C. freundii and K. aerogenes due to unacceptable performance and to address the high major error rate for P. mirabilis: - Perform an alternative method of testing prior to reporting results for the following antibiotic/organism combination(s): - Cefepime: Citrobacter freundii, Klebsiella aerogenes - Cefepime: Proteus mirabilis when the disk zone diameter from an eMcFarland inoculum produces a resistant result due to one major error. K231536 - Page 18 of 31 {18} A limitation statement is included in the device labeling to address the lack of testing with resistant Klebsiella oxytoca, Proteus mirabilis, Proteus vulgaris, and Serratia marcescens isolates. A total of 41 P. aeruginosa isolates were evaluated with cefepime. The combined results from clinical and challenge isolate testing demonstrated a CA of 95.1% with 0 minor errors and two major errors (2/21 = 9.5%) and 0 very major errors. Due to the lack of an intermediate interpretive criterion and since the eQUANT zone diameter of the two major errors were ≤3 mm difference compared to the zone diameter of the standard DD method, the major error rate was considered acceptable and the following footnote was included in the device labeling to address the high major error rate: The major error rate was ≥1.5% and considered acceptable since the eQUANT zone diameters for the major errors were ≤3 mm difference compared to the standard disk diffusion zone diameters. Ceftriaxone. A total of 223 Enterobacterales isolates (33 E. coli, 13 S. marcescens, 21 K. pneumoniae, 15 K. oxytoca, 42 K. aerogenes, 21 E. cloacae, 21 C. freundii, 16 P. vulgaris, and 41 P. mirabilis isolates) were evaluated with ceftriaxone. The combined results from clinical and challenge isolate testing demonstrated a CA of 96.9% with 5 minor errors, two major errors (2/134 = 1.5%) and 0 very major errors. When evaluating results by individual species, K. aerogenes had a CA of 92.9% with 2 minor errors, 1 major error (1/21 = 4.8%), and 0 very major errors. Since the eQUANT zone diameter of 1 of the 2 minor errors were ≤3 mm difference compared to the zone diameter of the standard DD method, the CA performance was considered acceptable and is addressed in a footnote included in the device labeling. In general, the eQUANT zone diameter for ceftriaxone/K. aerogenes results tended to be smaller (i.e., more resistant) compared to the standard DD method, which may contribute to the CA and cause the single major error, which is addressed in a footnote included in the device labeling. P. mirabilis had a CA of 92.7% with two minor errors, one major (1/32 = 3.1%) and 0 very major errors. Since the eQUANT zone diameter of 1 of the 2 minor errors were ≤3 mm difference compared to the zone diameter of the standard DD method, the CA performance was considered acceptable and is addressed in a footnote included in the device labeling. In general, the eQUANT zone diameter for ceftriaxone/P. mirabilis results tended to be smaller (i.e., more resistant) compared to the standard DD method, which may contribute to the CA and cause the single major error, which is addressed in a footnote included in the device labeling. To address the 90-95% CA performance and high major error rate for K. aerogenes and P. mirabilis when testing ceftriaxone, the following statement is included as a footnote to the performance table in the device labeling: A single major error was observed for the following drug/organism combinations which may be due to eQUANT zone diameters tending to be smaller than the standard disk diffusion zone diameters: Ceftriaxone: Klebsiella aerogenes, Proteus mirabilis In addition, the following footnote was included in the device labeling to address the 90-95% CA performance for K. aerogenes and P. mirabilis: K231536 - Page 19 of 31 {19} Categorical agreement was 90-95% due to minor errors for the following drug/organism combinations and considered acceptable since the eQUANT zone diameters of a significant number of the errors were ≤3 mm difference compared to the standard disk diffusion zone diameters: Ceftriaxone: Klebsiella aerogenes, Proteus mirabilis A limitation statement is included in the device labeling to address the lack of testing with resistant Proteus vulgaris isolates. **Ertapenem.** A total of 187 Enterobacterales isolates (40 E. coli, 41 S. marcescens, 21 K. pneumoniae, 16 K. oxytoca, 13 K. aerogenes, 8 E. cloacae, 21 C. freundii, 16 P. vulgaris, and 11 P. mirabilis isolates) were evaluated with ertapenem. The combined results from clinical and challenge isolate testing demonstrated a CA of 97.9% with 4 minor errors, 0 major and 0 very major errors. Overall, performance is acceptable. A limitation statement is included in the device labeling to address the lack of testing with resistant Klebsiella oxytoca and Proteus vulgaris isolates. **Gentamicin.** A total of 255 Enterobacterales isolates (80 E. coli, 22 S. marcescens, 21 K. pneumoniae, 16 K. oxytoca, 13 K. aerogenes, 21 E. cloacae, 41 C. freundii, 2 Citrobacter spp., 16 P. vulgaris, 22 P. mirabilis and one Proteus spp. isolates) were evaluated with gentamicin. The combined results from clinical and challenge isolate testing demonstrated a CA of 97.3% with 5 minor errors, 1 major error (1/227 = 0.4%) and 1 very major errors (1/26 = 3.8%). When evaluating results by individual species, E. coli had a CA of 97.5% with 0 minor, 1 major (1/75 = 1.3%), and 1 very major errors (1/4 = 25%). The one very major error (1/4 = 25%) was considered a random error due to the limited number of resistant isolates tested. Therefore, the performance was considered acceptable. A limitation statement is included in the device labeling to address the lack of testing with resistant Klebsiella oxytoca, Citrobacter freundii, Proteus vulgaris, and Serratia marcescens isolates. A total of 41 P. aeruginosa isolates were evaluated with gentamicin. The combined results from clinical and challenge isolate testing demonstrated a CA of 95.1% with two minor errors, 0 major and 0 very major errors. Overall, performance was acceptable. **Levofloxacin.** A total of 206 Enterobacterales isolates (40 E. coli, 21 S. marcescens, 41 K. pneumoniae, 16 K. oxytoca, 13 K. aerogenes, 8 E. cloacae, 11 C. freundii, 15 P. vulgaris, and 41 P. mirabilis isolates) were evaluated with levofloxacin. The combined results from clinical and challenge isolate testing demonstrated a CA of 96.1% with 8 minor errors, 0 major and 0 very major errors. When evaluating results by individual species, P. mirabilis had a CA of 92.7% with 3 minor errors, 0 major and 0 very major errors. Since the eQUANT zone diameter of the 3 minor errors were ≤3 mm difference compared to the zone diameter of the standard DD method, the CA performance was considered acceptable and the following footnote was included in the device labeling to address the 90-95% CA performance of P. mirabilis: Categorical agreement was 90-95% due to minor errors for the following drug/organism combinations and considered acceptable since the eQUANT zone K231536 - Page 20 of 31 {20} diameters of a significant number of the errors were ≤3 mm difference compared to the standard disk diffusion zone diameters: Levofloxacin: Proteus mirabilis A limitation statement is included in the device labeling to address the lack of testing with resistant Klebsiella oxytoca, Klebsiella aerogenes, Proteus vulgaris, and Serratia marcescens isolates. A total of 25 P. aeruginosa isolates were evaluated with levofloxacin. The combined results from clinical and challenge isolate testing demonstrated a CA of 96% with 1 minor, 0 major and 0 very major errors. Overall, performance was acceptable. ## Meropenem A total of 206 Enterobacterales isolates (76 E. coli, 40 S. marcescens, 19 K. pneumoniae, 16 K. oxytoca, 8 E. cloacae, 21 C. freundii, 16 P. vulgaris, and 10 P. mirabilis isolates) were evaluated with meropenem. The combined results from clinical and challenge isolate testing demonstrated a CA of 97.1% with 4 minor errors, 2 major error (2/180 = 1.1%) and 0 very major errors. When evaluating results by individual species, S. marcescens had a CA of 95% with 1 minor, 1 major (1/36 = 2.78%) and 0 very major errors. In general, the eQUANT zone diameter for meropenem/S. marcescens results tended to be smaller (i.e., more resistant) compared to the standard DD method, which may have caused the single major error. To address the high major error rate for S. marcescens, the following statement is included as a footnote to the performance table in the device labeling: The categorical agreement was ≥95% for the following drug/organism combinations; however, a single major error was observed which may be due to eQUANT zone diameters tending to be smaller than the standard disk diffusion zone diameters: Meropenem: Serratia marcescens A total of 25 P. aeruginosa isolates were evaluated with meropenem. The combined results from clinical and challenge isolate testing demonstrated a CA of 100% with 0 minor, 0 major and 0 very major errors. Overall, performance was acceptable. A total of 16 Acinetobacter spp. isolates were evaluated with meropenem. The combined results from clinical and challenge isolate testing demonstrated a CA of 100% with 0 minor, major and very major errors. Overall, performance was acceptable. ## Piperacillin/Tazobactam A total of 239 Enterobacterales isolates (157 E. coli, 23 S. marcescens, 21 K. pneumoniae, 16 P. vulgaris, and 22 P. mirabilis isolates) were evaluated with piperacillin/tazobactam. The combined results from clinical and challenge isolate testing demonstrated a CA of 94.1% with 14 minor errors, and 0 major error or 0 very major errors. When evaluating results by individual species, E. coli had a CA of 93.0% with 11 minor, 0 major and 0 very major errors. Since the eQUANT zone diameter of 7 of the 11 minor errors were ≤3 mm difference compared to the zone diameter of the standard DD method, the CA performance was considered acceptable and the following footnote was included in the device labeling to address the 90-95% CA performance: Categorical agreement was 90-95% due to minor errors for the following drug/organism combinations and considered acceptable since the eQUANT zone K231536 - Page 21 of 31 {21} diameters of a significant number of the errors were ≤3 mm difference compared to the standard disk diffusion zone diameters: Piperacillin/Tazobactam: Escherichia coli A limitation statement is included in the device labeling to address the lack of testing with resistant Proteus vulgaris isolates. A total of 25 P. aeruginosa isolates were evaluated with piperacillin/tazobactam. The combined results from clinical and challenge isolate testing demonstrated a CA of 96% with 1 minor, 0 major and 0 very major errors. Overall, performance was acceptable. A total of 41 Acinetobacter spp. isolates were evaluated with piperacillin/tazobactam. The combined results from clinical and challenge isolate testing demonstrated a CA of 95.1% with two minor errors, 0 major and 0 very major errors. Overall, performance was acceptable. Tobramycin. A total of 203 Enterobacterales isolates (60 E. coli, 13 S. marcescens, 21 K. pneumoniae, 16 K. oxytoca, 22 K. aerogenes, 21 E. cloacae, 11 C. freundii, 2 Citrobacter spp., 16 P. vulgaris, and 21 P. mirabilis isolates) were evaluated with tobramycin. The combined results from clinical and challenge isolate testing demonstrated a CA of 96.6% with 7 minor errors, 0 major and 0 very major errors. Overall, the performance was acceptable. A limitation statement is included in the device labeling to address the lack of testing with resistant Klebsiella aerogenes and Proteus vulgaris isolates. A total of 25 P. aeruginosa isolates were evaluated with tobramycin. The combined results from clinical and challenge isolate testing demonstrated a CA of 100% with 0 minor, 0 major and 0 very major errors. Overall, performance was acceptable. Table 6. eQUANT System Clinical Performance Compared to Standard DD | | Tot | No. CA | CA% | No. R or NS | No. S | min | maj | vmj | | --- | --- | --- | --- | --- | --- | --- | --- | --- | | Amoxicillin/Clavulanic Acid-Enterobacterales [Breakpoints (mm): ≥18(S), 14-17(I), ≤13(R)] | | | | | | | | | | Challenge Seeded | 3 | 3 | 100.0 | 1 | 2 | 0 | 0 | 0 | | Fresh | 37 | 33 | 89.1 | 6 | 25 | 3 | 1 | 0 | | Clinical Seeded | 183 | 174 | 95.1 | 53 | 123 | 9 | 0 | 0 | | Total | 223 | 210 | 94.2¹ | 60 | 150 | 12 | 1 | 0 | | Ampicillin-Escherichia coli [Breakpoints (mm): ≥17(S), 14-16(I), ≤13(R)] | | | | | | | | | | Challenge Seeded | - | - | - | - | - | - | - | - | | Fresh | 25 | 25 | 100.0 | 15 | 9 | 0 | 0 | 0 | | Clinical Seeded | 8 | 8 | 100.0 | 8 | 0 | 0 | 0 | 0 | | Total | 33 | 33 | 100.0 | 23 | 9 | 0 | 0 | 0 | | Aztreonam-Enterobacterales [Breakpoints (mm): ≥21(S), 18-20(I), ≤17(R)] | | | | | | | | | | Challenge Seeded | 7 | 7 | 100.0 | 1 | 5 | 0 | 0 | 0 | | Fresh | 40 | 38 | 95.0 | 4 | 36 | 2 | 0 | 0 | | Clinical Seeded | 142 | 138 | 97.2 | 40 | 100 | 3 | 1 | 0 | | Total | 189 | 183 | 96.8 | 45 | 141 | 5 | 1 | 0 | | Aztreonam-Pseudomonas aeruginosa [Breakpoints (mm): ≥22(S), 16-21(I), ≤15(R)] | | | | | | | | | | Challenge Seeded | 1 | 1 | 100.0 | 0 | 1 | 0 | 0 | 0 | | Fresh | 1 | 1 | 100.0 | 0 | 1 | 0 | 0 | 0 | K231536 - Page 22 of 31 {22} K231536 - Page 23 of 31 | | Tot | No. CA | CA% | No. R or NS | No. S | min | maj | vmj | | --- | --- | --- | --- | --- | --- | --- | --- | --- | | Clinical Seeded | 23 | 22 | 95.7 | 11 | 8 | 1 | 0 | 0 | | Total | 25 | 24 | 96.0 | 11 | 10 | 1 | 0 | 0 | | Cefazolin-Enterobacterales [Breakpoints (mm): ≥23(S), 20-22(I), ≤19(R)] | | | | | | | | | | Challenge Seeded | 2 | 1 | 50.0 | 1 | 1 | 1 | 0 | 0 | | Fresh | 37 | 28 | 75.7 | 12 | 19 | 9 | 0 | 0 | | Clinical Seeded | 174 | 152 | 87.4 | 85 | 51 | 21 | 1 | 0 | | Total | 213 | 181 | 85.0¹ | 98 | 71 | 31 | 1 | 0 | | Cefepime-Enterobacterales [Breakpoints (mm): ≥25(S), 19-24(I), ≤18(R)] | | | | | | | | | | Challenge Seeded | 7 | 7 | 100.0 | 0 | 6 | 0 | 0 | 0 | | Fresh | 40 | 38 | 95.0 | 4 | 33 | 2 | 0 | 0 | | Clinical Seeded | 190 | 173 | 91.1 | 38 | 123 | 16 | 1 | 0 | | Total | 237 | 218 | 92.0¹ | 42 | 162 | 18 | 1 | 0 | | Cefepime-Pseudomonas aeruginosa [Breakpoints (mm): ≥18(S), (-)(I), ≤17(R)] | | | | | | | | | | Challenge Seeded | 1 | 1 | 100.0 | 0 | 1 | 0 | 0 | 0 | | Fresh | 1 | 1 | 100.0 | 0 | 1 | 0 | 0 | 0 | | Clinical Seeded | 39 | 37 | 94.9 | 20 | 19 | 0 | 2 | 0 | | Total | 41 | 39 | 95.1 | 20 | 21 | 0 | 2 | 0 | | Ceftriaxone-Enterobacterales [Breakpoints (mm): ≥23(S), 20-22(I), ≤19(R)] | | | | | | | | | | Challenge Seeded | 7 | 7 | 100.0 | 2 | 5 | 0 | 0 | 0 | | Fresh | 40 | 39 | 97.5 | 7 | 33 | 0 | 1 | 0 | | Clinical Seeded | 176 | 170 | 97.0 | 75 | 96 | 5 | 1 | 0 | | Total | 223 | 216 | 96.9 | 84 | 134 | 5 | 2 | 0 | | Ertapenem-Enterobacterales Breakpoints (mm): ≥22(S), 19-21(I), ≤18(R)] | | | | | | | | | | Challenge Seeded | 7 | 7 | 100.0 | 0 | 7 | 0 | 0 | 0 | | Fresh | 40 | 40 | 100.0 | 0 | 40 | 0 | 0 | 0 | | Clinical Seeded | 140 | 136 | 97.1 | 29 | 106 | 4 | 0 | 0 | | Total | 187 | 183 | 97.9 | 29 | 153 | 4 | 0 | 0 | | Gentamicin-Enterobacterales [Breakpoints (mm): ≥15(S), 13-14(I), ≤12(R)] | | | | | | | | | | Challenge Seeded | 7 | 7 | 100.0 | 1 | 6 | 0 | 0 | 0 | | Fresh | 41 | 39 | 95.1 | 4 | 37 | 0 | 1 | 1 | | Clinical Seeded | 207 | 202 | 97.6 | 21 | 184 | 5 | 0 | 0 | | Total | 255 | 248 | 96.9 | 26 | 227 | 5 | 1 | 1 | | Gentamicin-Pseudomonas aeruginosa [Breakpoints (mm): ≥15(S), 13-14(I), ≤12(R)] | | | | | | | | | | Challenge Seeded | 1 | 1 | 100.0 | 0 | 1 | 0 | 0 | 0 | | Fresh | 1 | 1 | 100.0 | 0 | 1 | 0 | 0 | 0 | | Clinical Seeded | 39 | 37 | 94.9 | 17 | 21 | 2 | 0 | 0 | | Total | 41 | 39 | 95.1 | 17 | 23 | 2 | 0 | 0 | | Levofloxacin-Enterobacterales [Breakpoints (mm): ≥21(S), 17-20(I), ≤16(R)] | | | | | | | | | | Challenge Seeded | 7 | 7 | 100.0 | 1 | 5 | 0 | 0 | 0 | | Fresh | 40 | 37 | 92.5 | 7 | 33 | 3 | 0 | 0 | | Clinical Seeded | 159 | 154 | 96.9 | 41 | 108 | 5 | 0 | 0 | | Total | 206 | 198 | 96.1 | 49 | 146 | 8 | 0 | 0 | | Levofloxacin-Pseudomonas aeruginosa [Breakpoints (mm): ≥22(S), 15-21(I), ≤14(R)] | | | | | | | | | | Challenge Seeded | 1 | 1 | 100.0 | 0 | 1 | 0 | 0 | 0 | | Fresh | 1 | 1 | 100.0 | 0 | 1 | 0 | 0 | 0 | | Clinical Seeded | 23 | 22 | 95.7 | 11 | 6 | 1 | 0 | 0 | | Total | 25 | 24 | 96.0 | 11 | 8 | 1 | 0 | 0 | | Meropenem-Acinetobacter spp.[Breakpoints (mm): ≥18(S), 15-17(I), ≤14(R)] | | | | | | | | | | Challenge Seeded | - | - | - | - | - | - | - | - | | Fresh | - | - | - | - | - | - | - | - | | Clinical Seeded | 16 | 16 | 100.0 | 9 | 6 | 0 | 0 | 0 | | Total | 16 | 16 | 100.0 | 9 | 6 | 0 | 0 | 0 | | Meropenem-Enterobacterales [Breakpoints (mm): ≥23(S), 20-22(I), ≤19(R)] | | | | | | | | | | Challenge Seeded | 6 | 6 | 100.0 | 0 | 6 | 0 | 0 | 0 | {23} | | Tot | No. CA | CA% | No. R or NS | No. S | min | maj | vmj | | --- | --- | --- | --- | --- | --- | --- | --- | --- | | Fresh | 34 | 34 | 100.0 | 0 | 34 | 0 | 0 | 0 | | Clinical Seeded | 166 | 160 | 96.4 | 23 | 140 | 4 | 2 | 0 | | Total | 206 | 200 | 97.1 | 23 | 180 | 4 | 2 | 0 | | Meropenem-Pseudomonas aeruginosa [Breakpoints (mm): ≥19(S), 16-18(I), ≤15R)] | | | | | | | | | | Challenge Seeded | 1 | 1 | 100.0 | 0 | 1 | 0 | 0 | 0 | | Fresh | 1 | 1 | 100.0 | 0 | 1 | 0 | 0 | 0 | | Clinical Seeded | 23 | 23 | 100.0 | 17 | 6 | 0 | 0 | 0 | | Total | 25 | 25 | 100.0 | 17 | 8 | 0 | 0 | 0 | | Piperacillin-Tazobactam-Acinetobacter spp. [Breakpoints (mm): ≥21(S), 18-20(I), ≤17R)] | | | | | | | | | | Challenge Seeded | 2 | 2 | 100.0 | 1 | 1 | 0 | 0 | 0 | | Fresh | - | - | - | - | - | - | - | - | | Clinical Seeded | 39 | 37 | 94.9 | 24 | 15 | 2 | 0 | 0 | | Total | 41 | 39 | 95.1 | 25 | 16 | 2 | 0 | 0 | | Piperacillin-Tazobactam-Enterobacterales [Breakpoints (mm): ≥25(S), 21-24(I), ≤20R)] | | | | | | | | | | Challenge Seeded | 4 | 4 | 100.0 | 1 | 3 | 0 | 0 | 0 | | Fresh | 38 | 33 | 86.8 | 1 | 30 | 5 | 0 | 0 | | Clinical Seeded | 197 | 188 | 95.4 | 44 | 133 | 9 | 0 | 0 | | Total | 239 | 225 | 94.1¹ | 46 | 166 | 14 | 0 | 0 | | Piperacillin-Tazobactam - Pseudomonas aeruginosa [Breakpoints (mm): ≥21(S), 15-20(I), ≤14R)] | | | | | | | | | | Challenge Seeded | 1 | 1 | 100.0 | 0 | 1 | 0 | 0 | 0 | | Fresh | 1 | 1 | 100.0 | 0 | 1 | 0 | 0 | 0 | | Clinical Seeded | 23 | 22 | 95.7 | 9 | 12 | 1 | 0 | 0 | | Total | 25 | 24 | 96.0 | 9 | 14 | 1 | 0 | 0 | | Tobramycin-Enterobacterales [Breakpoints (mm): ≥15(S), 13-14(I), ≤12R)] | | | | | | | | | | Challenge Seeded | 7 | 7 | 100.0 | 1 | 6 | 0 | 0 | 0 | | Fresh | 40 | 37 | 92.5 | 3 | 36 | 3 | 0 | 0 | | Clinical Seeded | 156 | 152 | 97.4 | 29 | 122 | 4 | 0 | 0 | | Total | 203 | 196 | 96.6 | 33 | 164 | 7 | 0 | 0 | | Tobramycin-Pseudomonas aeruginosa [Breakpoints (mm): ≥15(S), 13-14(I), ≤12R)] | | | | | | | | | | Challenge Seeded | 1 | 1 | 100.0 | 0 | 1 | 0 | 0 | 0 | | Fresh | 1 | 1 | 100.0 | 0 | 1 | 0 | 0 | 0 | | Clinical Seeded | 23 | 23 | 100.0 | 8 | 14 | 0 | 0 | 0 | | Total | 25 | 25 | 100.0 | 8 | 16 | 0 | 0 | 0 | CA – Category Agreement R – Resistant isolates min – minor errors NS – Non-susceptible isolates maj – major errors S – Susceptible isolates vmj – very major errors ¹CA Performance (<95%) is described above and addressed in device labeling. ## Trending A trending analysis was conducted using the combined data (fresh, clinical seeded and challenge seeded) to evaluate antimicrobial-organism combinations for which DD zone diameters obtained from eQUANT inoculum tended to be ≥ 3 mm smaller or larger than DD zone diameters obtained from the standard DD method (colony inoculum). Trending results were stratified by species to determine if species-related trends were observed (Table 7). Species for which the difference between the percentage of isolates with larger or smaller zone diameter sizes was ≥15% with a statistically significant confidence interval were considered to have evidence of trending. K231536 - Page 24 of 31 {24} Table 7. Trending by Species (fresh, clinical seeded and challenge seeded samples) | | eQUANT System | | | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | | Drug | Organism | Total | ≥3 mm Smaller Zone Size # (%) | Equivalent Zone Size (-2 to +2 mm) | ≥3mm Larger Zone Size # (%) | Percent Difference (95% CI) | Trending Noted (≥15%) | | Amoxicillin-Clavulanate | E. coli | 146 | 5 (3.4) | 138 | 3 (2.1) | +1.3% (-2.9%, 5.9%) | No | | Amoxicillin-Clavulanate | K. oxytoca | 15 | 2 (13.3) | 12 | 1 (6.7) | +6.6% (-18.4%, 31.8%) | No | | Amoxicillin-Clavulanate | K. pneumoniae | 21 | 1 (4.8) | 20 | 0 (0) | +4.8% (-11.2%, 22.7%) | No | | Amoxicillin-Clavulanate | P. mirabilis | 41 | 14 (34.1) | 27 | 0 (0) | +34.1% (18.9%, 49.5%) | Yes | | Ampicillin | E. coli | 33 | 1 (3.2) | 31 | 1 (3.2) | 0.0% (-12.5%, 12.5%) | No | | Aztreonam | C. freundii | 11 | 2 (18.2) | 9 | 0 (0.0) | +18.2% (-10.8%, 47.7%) | Yes | | Aztreonam | Citrobacter spp. | 2 | 0 (0.0) | 2 | 0 (0.0) | 0.0% (-65.8%, 65.8%) | No | | Aztreonam | E. cloacae | 8 | 0 (0.0) | 8 | 0 (0.0) | 0.0% (-32.4%, 32.4%) | No | | Aztreonam | E. coli | 60 | 14 (23.3) | 44 | 2 (3.3) | +20.0 (8.0%, 32.3%) | Yes | | Aztreonam | K. aerogenes | 22 | 3 (13.6) | 19 | 0 (0.0) | +13.6 (-3.7%, 33.3%) | No | | Aztreonam | K. oxytoca | 15 | 1 (6.7) | 14 | 0 (0.0) | +6.7% (-14.5%, 29.8%) | No | | Aztreonam | K. pneumoniae | 21 | 0 (0.0) | 21 | 0 (0.0) | 0.0% (-15.5%, 15.5%) | No | | Aztreonam | P. mirabilis | 21 | 6 (28.6) | 15 | 0 (0.0) | +28.6% (7.2%, 50.0%) | Yes | | Aztreonam | P. vulgaris | 16 | 7 (43.8) | 8 | 1 (6.3) | +37.5% (7.3%, 61.1%) | Yes | | Aztreonam | S. marcescens | 13 | 2 (15.4) | 10 | 1 (7.7) | +7.7% (-20.2%, 35.3%) | No | | Aztreonam | P. aeruginosa | 25 | 0 (0.0) | 25 | 0 (0.0) | +0.0% (-13.3%, 13.3%) | No | | Cefazolin | E. coli | 131 | 8 (6.1) | 118 | 5 (3.8) | +2.3% (-3.4%, 8.2%) | No | | Cefazolin | K. pneumoniae | 41 | 0 (0) | 38 | 3 (7.3) | -7.3% (-19.4%, 2.5%) | No | | Cefazolin | P. mirabilis | 41 | 4 (9.8) | 37 | 0 (0.0) | +9.8% (-0.6%, 22.6%) | No | | Cefepime | C. freundii | 21 | 2 (9.5) | 14 | 5 (23.8) | -14.3% (-36.7%, 9.2%) | No | | Cefepime | E. cloacae | 41 | 2 (4.9) | 31 | 8 (19.5) | -14.6% (-29.6%, 0.0%) | No | | Cefepime | E. coli | 40 | 10 (25.0) | 27 | 3 (7.5) | +17.5% (1.1%, 33.5%) | Yes | | Cefepime | K. aerogenes | 21 | 5 (23.8) | 16 | 0 (0.0) | +23.8% (3.5%, 45.1%) | Yes | | Cefepime | K. oxytoca | 15 | 2 (13.3) | 12 | 1 (6.7) | +6.6% (-18.4%, 31.8%) | No | | Cefepime | K. pneumoniae | 21 | 2 (9.5) | 18 | 1 (4.8) | +4.7% (-14.4%, 24.5%) | No | | Cefepime | P. mirabilis | 41 | 15 (36.6) | 26 | 0 (0.0) | +36.6% | Yes | K231536 - Page 25 of 31 {25} K231536 - Page 26 of 31 | | eQUANT System | | | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | | Drug | Organism | Total | ≥3 mm Smaller Zone Size # (%) | Equivalent Zone Size (-2 to +2 mm) | ≥3mm Larger Zone Size # (%) | Percent Difference (95% CI) | Trending Noted (≥15%) | | | | | | | | (21.0%, 51.9%) | | | Cefepime | *P. vulgaris* | 16 | 8 (50.0) | 7 | 1 (6.3) | +43.5% (12.6%, 66.3%) | Yes | | Cefepime | *S. marcescens* | 21 | 3 (14.3) | 18 | 0 (0.0) | +14.3% (-3.8%, 34.6%) | No | | Cefepime | *P. aeruginosa* | 41 | 6 (14.6) | 35 | 0 (0.0) | +14.6% (3.1%, 28.4%) | No | | Ceftriaxone | *C. freundii* | 21 | 1 (4.8) | 17 | 3 (14.3) | -9.5% (-30.3%, 10.7%) | No | | Ceftriaxone | *E. cloacae* | 21 | 1 (4.8) | 17 | 3 (14.3) | -9.5% (-30.3%, 10.7%) | No | | Ceftriaxone | *E. coli* | 33 | 8 (24.2) | 25 | 0 (0.0) | +24.2% (8.8%, 41.0%) | Yes | | Ceftriaxone | *K. aerogenes* | 42 | 13 (31.0) | 29 | 0 (0.0) | +31.0% (16.4%, 46.0%) | Yes | | Ceftriaxone | *K. oxytoca* | 15 | 1 (6.7) | 12 | 2 (13.3) | -6.7% (-31.8%, 18.4%) | No | | Ceftriaxone | *K. pneumoniae* | 21 | 1 (4.8) | 20 | 0 (0.0) | +4.8% (-11.2%, 22.7%) | No | | Ceftriaxone | *P. mirabilis* | 41 | 15 (36.6) | 26 | 0 (0.0) | +36.6% (21.0%, 51.9%) | Yes | | Ceftriaxone | *P. vulgaris* | 16 | 5 (31.3) | 11 | 0 (0.0) | +31.3% (5.4%, 55.6%) | Yes | | Ceftriaxone | *S. marcescens* | 13 | 0 (0.0) | 13 | 0 (0.0) | 0.0% (-22.8%, 22.8%) | No | | Ertapenem | *C. freundii* | 21 | 3 (14.3) | 14 | 4 (19.0) | -4.8% (-27.7%, 18.6%) | No | | Ertapenem | *E. cloacae* | 8 | 1 (12.5) | 7 | 0 (0.0) | +12.5% (-21.5%, 47.1%) | No | | Ertapenem | *E. coli* | 40 | 8 (20.0) | 30 | 2 (5.0) | +15.0% (0.1%, 30.2%) | Yes | | Ertapenem | *K. aerogenes* | 13 | 1 (7.7) | 12 | 0 (0.0) | +7.7% (-16.0%, 33.3%) | No | | Ertapenem | *K. oxytoca* | 16 | 4 (25.0) | 11 | 1 (6.3) | +18.8% (-7.8%, 43.8%) | Yes | | Ertapenem | *K. pneumoniae* | 21 | 0 (0.0) | 21 | 0 (0.0) | 0.0% (-15.5%, 15.5%) | No | | Ertapenem | *P. mirabilis* | 11 | 2 (18.2) | 9 | 0 (0.0) | +18.2% (-10.8%, 47.7%) | Yes | | Ertapenem | *P. vulgaris* | 16 | 7 (43.8) | 9 | 0 (0.0) | +43.8% (15.4%, 66.8%) | Yes | | Ertapenem | *S. marcescens* | 41 | 15 (36.6) | 26 | 0 (0.0) | +36.6% (21.0%, 51.9%) | Yes | | Gentamicin | *C. freundii* | 41 | 5 (12.2) | 34 | 2 (4.9) | +7.3% (-5.9%, 21.1%) | No | | Gentamicin | *Citrobacter spp.* | 2 | 0 (0.0) | 2 | 0 (0.0) | 0.0% (-65.8%, 65.8%) | No | | Gentamicin | *E. cloacae* | 21 | 0 (0.0) | 21 | 0 (0.0) | 0.0% (-15.5%, 15.5%) | No | | Gentamicin | *E. coli* | 80 | 4 (5.0) | 75 | 1 (1.3) | +3.8% (-2.5%, 11.0%) | No | | Gentamicin | *K. aerogenes* | 13 | 2 (15.4) | 11 | 0 (0.0) | +15.4% | Yes | {26} K231536 - Page 27 of 31 | | eQUANT System | | | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | | Drug | Organism | Total | ≥3 mm Smaller Zone Size # (%) | Equivalent Zone Size (-2 to +2 mm) | ≥3mm Larger Zone Size # (%) | Percent Difference (95% CI) | Trending Noted (≥15%) | | | | | | | | (-42.2%, 10.0%) | | | Gentamicin | K. oxytoca | 16 | 0 (0.0) | 16 | 0 (0.0) | 0.0% (-19.4%, 19.4%) | No | | Gentamicin | K. pneumoniae | 21 | 0 (0.0) | 21 | 0 (0.0) | 0.0% (-15.5%, 15.5%) | No | | Gentamicin | P. mirabilis | 22 | 3 (13.6) | 19 | 0 (0.0) | +13.6% (-3.7%, 33.3%) | No | | Gentamicin | Proteus spp. | 1 | 0 (0.0) | 1 | 0 (0.0) | 0.0% (-79.4%, 79.4%) | No | | Gentamicin | P. vulgaris | 16 | 3 (18.8) | 13 | 0 (0.0) | +18.8% (-4.1%, 43.0%) | Yes | | Gentamicin | S. marcescens | 22 | 0 (0.0) | 22 | 0 (0.0) | 0.0% (-14.9%, 14.9%) | No | | Gentamicin | P. aeruginosa | 41 | 0 (0.0) | 41 | 0 (0.0) | 0.0% (-8.6%, 8.6%) | No | | Levofloxacin | C. freundii | 11 | 0 (0.0) | 11 | 0 (0.0) | 0.0% (-25.9%, 25.9%) | No | | Levofloxacin | E. cloacae | 8 | 0 (0.0) | 8 | 0 (0.0) | 0.0% (-32.4%, 32.4%) | No | | Levofloxacin | E. coli | 40 | 2 (5.0) | 35 | 3 (7.5) | -2.5% (-15.4%, 10.0%) | No | | Levofloxacin | K. aerogenes | 13 | 2 (15.4) | 11 | 0 (0.0) | +15.4% (-10.0%, 42.2%) | Yes | | Levofloxacin | K. oxytoca | 16 | 0 (0.0) | 13 | 3 (18.8) | -18.8% (-43.0%, 4.1%) | Yes | | Levofloxacin | K. pneumoniae | 41 | 1 (2.4) | 36 | 4 (9.8) | -7.3% (-20.3%, 4.4%) | No | | Levofloxacin | P. mirabilis | 41 | 5 (12.2) | 34 | 2 (4.9) | +7.3% (-5.9%, 21.1%) | No | | Levofloxacin | P. vulgaris | 15 | 3 (20.0) | 10 | 2 (13.3) | +6.7% (-21.1%, 33.6%) | No | | Levofloxacin | S. marcescens | 21 | 1 (4.8) | 20 | 0 (0.0) | +4.8% (-11.2%, 22.7%) | No | | Levofloxacin | P. aeruginosa | 25 | 0 (0.0) | 25 | 0 (0.0) | 0.0% (-13.3%, 13.3%) | No | | Meropenem | Acinetobacter spp. | 16 | 1 (6.3) | 14 | 1 (6.3) | 0.0% (-22.7%, 22.7%) | No | | Meropenem | C. freundii | 21 | 5 (23.8) | 11 | 5 (23.8) | 0.0% (-25.0%, 25.0%) | No | | Meropenem | E. cloacae | 8 | 1 (12.5) | 7 | 0 (0.0) | +12.5% (-21.5%, 47.1%) | No | | Meropenem | E. coli | 76 | 14 (18.4) | 55 | 7 (9.2) | +9.2% (-2.0%, 20.4%) | No | | Meropenem | K. oxytoca | 16 | 2 (12.5) | 12 | 2 (12.5) | 0.0% (-25.2%, 25.2%) | No | | Meropenem | K. pneumoniae | 19 | 1 (5.3) | 18 | 0 (0.0) | +5.3% (-12.1%, 24.6%) | No | | Meropenem | P. mirabilis | 10 | 2 (20.0) | 8 | 0 (0.0) | +20.0% (-11.2%, 51.0%) | Yes | | Meropenem | P. vulgaris | 16 | 3 (18.8) | 13 | 0 (0.0) | +18.8% (-4.1%, 43.0%) | Yes | | Meropenem | S. marcescens | 40 | 15 (37.5) | 25 | 0 (0.0) | +37.5% | Yes | {27} | | eQUANT System | | | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | | Drug | Organism | Total | ≥3 mm Smaller Zone Size # (%) | Equivalent Zone Size (-2 to +2 mm) | ≥3mm Larger Zone Size # (%) | Percent Difference (95% CI) | Trending Noted (≥15%) | | | | | | | | (21.6%, 53.0%) | | | Meropenem | P. aeruginosa | 25 | 0 (0.0) | 25 | 0 (0.0) | 0.0% (-13.3%, 13.3%) | No | | Piperacillin-Tazobactam | Acinetobacter spp. | 41 | 3 (7.3) | 38 | 0 (0.0) | +7.3% (-2.5%, 19.4%) | No | | Piperacillin-Tazobactam | E. coli | 157 | 19 (12.5) | 137 | 1 (5.7) | +11.5% (6.4%, 17.5%) | No | | Piperacillin-Tazobactam | K. pneumoniae | 21 | 2 (9.5) | 19 | 0 (0.0) | +9.5% (-7.4%, 28.9%) | No | | Piperacillin-Tazobactam | P. mirabilis | 22 | 7 (31.8) | 15 | 0 (0.0) | +31.8% (10.4%, 52.7%) | Yes | | Piperacillin-Tazobactam | P. vulgaris | 16 | 6 (37.5) | 10 | 0 (0.0) | +37.5% (10.4%, 61.4%) | Yes | | Piperacillin-Tazobactam | S. marcescens | 23 | 2 (8.7) | 21 | 0 (0.0) | +8.7% (-6.9%, 26.8%) | No | | Piperacillin-Tazobactam | P. aeruginosa | 25 | 1 (4.0) | 24 | 0 (0.0) | +4.0% (-9.7%, 19.5%) | No | | Tobramycin…

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