LifeScale Gram Negative Kit (LSGN) with the LifeScale AST system

K241324 · Affinity Biosensors, LLC · SAN · Oct 23, 2024 · Microbiology

Device Facts

• Record ID: K241324
• Device Name: LifeScale Gram Negative Kit (LSGN) with the LifeScale AST system
• Applicant: Affinity Biosensors, LLC
• Product Code: SAN · Microbiology
• Decision Date: Oct 23, 2024
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.1650
• Device Class: Class 2
• Attributes: PCCP

Intended Use

The LifeScale AST system is a multiplexed in vitro diagnostic test that uses a microfluidic sensor and resonant frequency to calculate organism concentration and/or mass distribution for quantitative antimicrobial susceptibility testing (AST). Testing is performed directly on blood cultures signaled as positive by a continuous monitoring blood culture system and confirmed by Gram stain. The LifeScale AST system does not provide organism identification and is not indicated for use with polymicrobial samples. Interpretive results (Susceptible/Intermediate/Susceptible-dose dependent/Resistant) are provided for specific drug/organism combinations. 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.

Device Story

LifeScale AST system uses microfluidic sensor and resonant frequency to measure organism concentration and mass distribution in positive blood culture samples. System automatically prepares inoculum from positive blood culture; calculates MICs for specific antimicrobial agents. Used in clinical laboratories; operated by technicians. Output provides quantitative MIC and categorical interpretation (S/I/SDD/R). Results assist clinicians in selecting appropriate antimicrobial therapy for gram-negative bacilli infections. System requires subculture for purity confirmation; not for polymicrobial samples. Processing must occur within 12 hours of bottle positivity.

Clinical Evidence

Clinical performance evaluated across 6 US sites using prospective and contrived positive blood culture samples. Compared to reference BMD (CLSI M07). Performance metrics included Essential Agreement (EA), Category Agreement (CA), and discrepancy rates (VMJ, MAJ, MIN). Overall EA/CA generally >90%. Study included 6,164 initiated tests with 2.38% exclusion rate. Limitations included for specific drug/organism combinations showing high/low trending or unacceptable categorical agreement.

Technological Characteristics

Microfluidic sensor; resonant frequency measurement principle. Semi-automated instrument. Dimensions/form factor: benchtop system. Connectivity: standalone. Software: automated MIC calculation and interpretation based on FDA/CLSI breakpoints. Sterilization: N/A (kit components).

Indications for Use

Indicated for in vitro testing of positive blood culture samples confirmed by Gram stain as containing gram-negative bacilli for specific antimicrobial agents and target organisms including E. coli, K. pneumoniae, K. aerogenes, K. oxytoca, K. variicola, Acinetobacter spp., and P. aeruginosa. Not indicated for polymicrobial samples.

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

• LifeScale Gram Negative Kit (LSGN) with the LifeScale AST system (K211815)

Submission Summary (Full Text)

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October 23, 2024

Affinity Biosensors, LLC Nicole Holliday Director of Clinical Studies 222 East Canon Perdido Street Santa Barbara, California 93101

Re: K241324

Trade/Device Name: LifeScale Gram Negative Kit (LSGN) with the LifeScale AST system Regulation Number: 21 CFR 866.1650 Regulation Name: A Cellular Analysis System For Multiplexed Antimicrobial Susceptibility Testing Regulatory Class: Class II Product Code: SAN, LON Dated: September 23, 2024 Received: September 23, 2024

Dear Nicole Holliday:

We have reviewed your section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (the Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database available at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

FDA's substantial equivalence determination also included the review and clearance of your Predetermined Change Control Plan (PCCP). Under section 515C(b)(1) of the Act, a new premarket notification is not required for a change to a device cleared under section 510(k) of the Act, if such change is consistent with an established PCCP granted pursuant to section 515C(b)(2) of the Act. Under 21 CFR 807.81(a)(3), a new premarket notification is required if there is a major change or modification in the intended use of a device,

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or if there is a change or modification in a device that could significantly affect the safety or effectiveness of the device, e.g., a significant change or modification in design, material, chemical composition, energy source, or manufacturing process. Accordingly, if deviations from the established PCCP result in a major change or modification in the intended use of the device, or result in a change or modification in the device that could significantly affect the safety or effectiveness of the a new premarket notification would be required consistent with section 515C(b)(1) of the Act and 21 CFR 807.81(a)(3). Failure to submit such a premarket submission would constitute adulteration and misbranding under sections 501(f)(1)(B) and 502(o) of the Act, respectively.

Additional information about changes that may require a new premarket notification are provided in the FDA guidance documents entitled "Deciding When to Submit a 510(k) for a Change to an Existing Device" (https://www.fda.gov/media/99812/download) and "Deciding When to Submit a 510(k) for a Software Change to an Existing Device" (https://www.fda.gov/media/99785/download).

Your device is also subject to, among other requirements, the Quality System (QS) regulation (21 CFR Part 820), which includes, but is not limited to, 21 CFR 820.30, Design controls; 21 CFR 820.90, Nonconforming product; and 21 CFR 820.100. Corrective and preventive action. Please note that regardless of whether a change requires premarket review, the QS regulation requires device manufacturers to review and approve changes to device design and production (21 CFR 820.30 and 21 CFR 820.70) and document changes and approvals in the device master record (21 CFR 820.181).

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801 and Part 809); medical device reporting of medical device-related adverse events) (21 CFR Part 803) for devices or postmarketing safety reporting (21 CFR Part 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safetyreporting-combination-products); good manufacturing practice requirements as set forth in the quality systems (OS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR Part 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR Parts 1000-1050.

All medical devices, including Class I and unclassified devices and combination product device constituent parts are required to be in compliance with the final Unique Device Identification System rule ("UDI Rule"). The UDI Rule requires, among other things, that a device bear a unique device identifier (UDI) on its label and package (21 CFR 801.20(a)) unless an exception or alternative applies (21 CFR 801.20(b)) and that the dates on the device label be formatted in accordance with 21 CFR 801.18. The UDI Rule (21 CFR 830.300(a) and 830.320(b)) also requires that certain information be submitted to the Global Unique Device Identification Database (GUDID) (21 CFR Part 830 Subpart E). For additional information on these requirements, please see the UDI System webpage at https://www.fda.gov/medical-device-advicecomprehensive-regulatory-assistance/unique-device-identification-system-udi-system.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part

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3

803), please go to https://www.fda.gov/medical-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.

For comprehensive regulatory information about medical devices and radiation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medicaldevices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email ([e-mail]) or phone [phone] or 301-796-7100).

Sincerely,

# Ribhi Shawar -S

Ribhi Shawar, Ph.D. (ABMM) Branch Chief, General Bacteriology and Antimicrobial Susceptibility Branch Division of Microbiology Devices OHT7: Office of In Vitro Diagnostics Office of Product Evaluation and Quality Center for Devices and Radiological Health

Enclosure

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# Indications for Use

510(k) Number (if known) K241324

#### Device Name

LifeScale Gram Negative Kit (LSGN) with the LifeScale AST system

#### Indications for Use (Describe)

The LifeScale AST system is a multiplexed in vitro diagnostic test that uses a microfluidic sensor and resonant frequency to calculate organism concentration and/or mass distribution for quantitative antimicrobial susceptibility testing (AST). Testing is performed directly on blood cultures signaled as postituous monitoring blood culture system and confirmed by Gram stain. The LifeScale AST system does not provide organism identification and is not use with polymicrobial samples. Interpretive results (Susceptible/Intermediate/Susceptible-dose dependent/Resistant) are provided for specific drug/organism combinations. 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 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 and for epidemiologic testing and for recovery of organisms present in microbial samples.

The LifeScale AST System and the LifeScale Gram-negative Panel (LSGN) are indicated for testing of positive blood culture samples confirmed by Gram stain as containing Gram-negative organisms for the following antimicrobial agents and specific target organisms identified below:

• Amikacin: Acinetobacter spp., Escherichia coli, Klebsiella aerogenes, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella variicola, Pseudomonas aeruginosa

· Ampicillin: Escherichia coli

- · Aztreonam: Escherichia coli, Klebsiella pneumoniae, Klebsiella aerogenes, Klebsiella oxytoca
- · Cefazolin: Escherichia coli, Klebsiella pneumoniae, Klebsiella variicola
- · Cefepime: Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Pseudomonas aeruginosa

· Ceftazidime: Acinetobacter spp. (other than Acinetobacter ursingii), Escherichia aerogenes, Klebsiella oxytoca, Klebsiella variicola, Klebsiella pneumoniae, Pseudomonas aeruginosa

- · Ceftazidime-avibactam: Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca
- Ertapenem: Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Klebsiella oxytoca

• Gentamicin: Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Klebsiella variicola, Pseudomonas aeruginosa

· Levofloxacin: Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Pseudomonas aeruginosa

- Meropenem: Acinetobacter spp., Escherichia coli, Klebsiella oxytoca, Pseudomonas aeruginosa
- Meropenem-vaborbactam: Escherichia coli, Klebsiella pneumoniae, Klebsiella aerogenes, Klebsiella oxytoca
- Piperacillin-tazobactam: Acinetobacter spp., Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa
- Trimethoprim-sulfamethoxazole: Escherichia coli, Klebsiella oxytoca, Klebsiella variicola

Type of Use (Select one or both, as applicable)

> Prescription Use (Part 21 CFR 801 Subpart D)

Over-The-Counter Use (21 CFR 801 Subpart C)

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# 510(k) Substantial Equivalence Determination Performance Summary In Compliance with Section 807.92(c)

# 1. Contact Details

| Submitter: | Affinity Biosensors |
|------------|---------------------------------|
| | 222 East Canon Perdido Street |
| | Suite 101 |
| | Santa Barbara, California 93101 |
| | [phone] |

| Correspondent: | Nicole Holliday<br>Director of Clinical Studies<br>Affinity Biosensors<br>222 East Canon Perdido Street<br>Suite 101<br>Santa Barbara, California 93101<br>[phone] |
|----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

# 2. Device

Name of Device: LifeScale™ Gram Negative Kit (LSGN) with the LifeScale AST system Common or Usual Name: LifeScale AST system

#### Regulation Name:

A cellular analysis system for multiplexed antimicrobial susceptibility testing

## Regulation Number:

21 CFR 866.1650 Regulatory Class: Class II Product Code: SAN, LON Predicate Device: K211815 LifeScale™ Gram Negative Kit (LSGN) with the LifeScale AST system

## Purpose for Submission:

- To obtain a substantial equivalence determination for the following antimicrobial i. agents to the LifeScale Gram Negative Kit (LSGN) Kit: Amikacin, Cefepime, Ceftazidime-avibactam, Gentamicin, Levofloxacin, Meropenem-vaborbactam and Piperacillin-tazobactam. The LSGN Kit is used with the LifeScale AST system for testing positive blood culture samples containing gram-negative bacilli.
#### Cleared Antimicrobial/Organism Combinations (K211815):

- 1. Ampicillin: Escherichia coli
- 2. Aztreonam: Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca
- 3. Cefazolin: Klebsiella pneumoniae, Klebsiella variicola

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- 4. Ceftazidime: Acinetobacter baumannii, Acinetobacter baumannii/nosocomialis group, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella variicola, Pseudomonas aeruginosa
- 5. Ertapenem: Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca
- 6. Trimethoprim-Sulfamethoxazole: Escherichia coli, Klebsiella oxytoca, Klebsiella variicola

#### Additional Claimed Antimicrobial/Organism Combinations (Current Submission):

- 7. Amikacin: Acinetobacter spp., Escherichia coli, Klebsiella pneumoniae, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella variicola, Pseudomonas aeruginosa
- 8. Cefepime: Escherichia coli, Klebsiella pneumoniae, Klebsiella aerogenes, Klebsiella oxytoca, Pseudomonas aeruginosa
- 9. Ceftazidime-avibactam: Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca
- 10. Gentamicin: Escherichia coli, Klebsiella pneumoniae, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella variicola, Pseudomonas aeruqinosa
- 11. Levofloxacin: Escherichia coli, Klebsiella pneumoniae, Klebsiella aerogenes, Klebsiella oxytoca, Pseudomonas aeruginosa
- 12. Meropenem: Acinetobacter spp., Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Pseudomonas aeruginosa
- 13. Meropenem-vaborbactam: Escherichia coli, Klebsiella pneumoniae, Klebsiella aerogenes, Klebsiella oxytoca
- 14. Piperacillin-tazobactam: Acinetobacter spp., Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruqinosa
- ii. Removal of limitations included in in the cleared LifeScale LSGN Kit with the LifeScale AST system (K211815) for Aztreonam, Ceftazidime, Ertapenem, and Cefazolin.

| | Antimicrobial/Organism | Limitation | Action |
|----|-------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------|
| 1. | Ertapenem/E. coli | Due to unacceptable performance of<br>ertapenem/E. coli with incubation in an<br>off-line incubator, perform an<br>alternative method of testing prior to<br>reporting results for ertapenem/E. coli<br>when panels are incubated in an off-line<br>incubator. | Accept Removal. Additional<br>clinical testing and revised IFU<br>provided for review |
| 2. | Aztreonam/ K.<br>pneumoniae | Perform an alternative method of<br>testing prior to reporting results for the<br>following antimicrobial/organism<br>combination(s): Aztreonam/K.<br>pneumoniae | Accept Removal. Additional<br>clinical testing and revised IFU<br>provided for review |
| 3. | Ceftazidime/ K.<br>pneumoniae | Perform an alternative method of<br>testing prior to reporting results for the<br>following antimicrobial/organism<br>combination(s): Ceftazidime/K.<br>pneumoniae | Accept Removal. Additional<br>clinical testing and revised IFU<br>provided for review |

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| 4. | Ceftazidime/<br>Acinetobacter spp. | Perform an alternative method of<br>testing prior to reporting results for the<br>following antimicrobial/organism<br>combination(s):<br>Ceftazidime/Acinetobacter spp. (other<br>than A. baumannii and A.<br>baumannii/nosocomialis group) | Revise current limitation<br>specifically to Acinetobacter<br>ursingii<br>Revised Limitation:<br>Perform an alternative method<br>of testing prior to reporting<br>results for the following<br>antimicrobial/organism<br>combination(s): Ceftazidime:<br>Acinetobacter ursingii (revised<br>IFU provided for review.) |
|----|------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| 5. | Cefazolin/E. coli | Perform an alternative method of<br>testing prior to reporting results for the<br>following antimicrobial/organism<br>combination(s): Cefazolin/E. coli | Accept Removal. Additional<br>clinical testing and revised IFU<br>provided for review |
| 6. | Ertapenem/ K.<br>pneumoniae | Perform an alternative method of<br>testing prior to reporting results for the<br>following antimicrobial/organism<br>combination(s): Ertapenem/K.<br>pneumoniae | Accept Removal. Additional<br>clinical testing and revised IFU<br>provided for review |

# Antimicrobials:

| Table 1. LifeScale LSGN Antimicrobials and Reportable Ranges | |
|--------------------------------------------------------------|--|
|--------------------------------------------------------------|--|

| Antimicrobial | | Range µg/mL | |
|------------------------------------|------|-------------|---------|
| | | Min (≤) | Max (>) |
| Amikacin | AMI | 4 | 256 |
| *Ampicillin | AMP | 2 | 64 |
| *Aztreonam | AZT | 1 | 64 |
| *Cefazolin | FAZ | 0.25 | 16 |
| Cefepime | FEP | 0.5 | 64 |
| *Ceftazidime | TAZ | 1 | 64 |
| Ceftazidime-avibactam | CZA | 2/4 | 32/4 |
| *Ertapenem | ETP | 0.12 | 8 |
| Gentamicin | GEN | 1 | 32 |
| Levofloxacin | LEVO | 0.25 | 16 |
| Meropenem | MERO | 0.12 | 16 |
| Meropenem-vaborbactam | MEV | 0.5/8 | 16/8 |
| Piperacillin-tazobactam | P/T | 4/4 | 256/4 |
| *Trimethoprim-<br>sulfamethoxazole | SXT | 0.25 | 8 |

*Antimicrobics cleared in K211815

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## Test Type:

The LifeScale Gram Negative Kit (LSGN) with the LifeScale AST system is a quantitative antimicrobial susceptibility test system that determines the minimum inhibitory concentration of specific organisms from positive blood culture samples.

# 3. Device Description

The Affinity Biosensors LifeScale Gram Negative Kit (LSGN) is a semi-automated instrument system for antimicrobial susceptibility testing (AST) directly from positive blood cultures for which the Gram stain shows gram-negative bacilli. The system uses a microfluidic sensor that detects organisms in suspension and measures differences in cell mass between bacterial suspensions incubated in the presence and absence of antibiotic. Minimum inhibitory concentrations (MICs) are determined from data obtained during sample measurement including organism concentration and/or cell mass distributions of individual organisms. The system automatically interprets the measurements to determine MIC values and interpretive results (susceptible, intermediate, or resistant) based on FDA-defined or recognized breakpoints. The organism identification determined using a platform FDA-cleared for use with positive blood culture samples is entered by the user. If the organism identification has not been entered or if the sample has not been confirmed as monomicrobial, the system provides a preliminary report that indicates that organism identification or monomicrobial status is pending. The device Instructions for Use indicates that the preliminary laboratory report should not be reported to the healthcare provider. The final report is provided to the healthcare provider when the organism identification is entered into the system and the culture is confirmed to be monomicrobial samples should not be tested with the LifeScale LSGN Kit. Preliminary results are available in most cases within four hours from initiation of the assay.

# 4. Intended Use/Indications for Use

## Intended Use:

The LifeScale AST system is a multiplexed in vitro diagnostic test that uses a microfluidic sensor and resonant frequency to calculate organism concentration and/or mass distribution for quantitative antimicrobial susceptibility testing (AST). Testing is performed directly on blood cultures signaled as positive by a continuous monitoring blood culture system and confirmed by Gram stain. The LifeScale AST system does not provide organism identification and is not indicated for use with polymicrobial samples. Interpretive results (Susceptible/Intermediate/Susceptible-dose dependent/Resistant) are provided for specific drug/organism combinations. 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 and for epidemiologic testing and for recovery of organisms present in microbial samples.

## Indications for Use:

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The LifeScale Gram Negative Kit (LSGN) is intended for use with the LifeScale AST system for in vitro testing of positive blood culture samples confirmed by Gram stain as containing gram-negative bacilli for the antimicrobial agents and specific target organisms identified below:

- 1. Ampicillin: Escherichia coli
- 2. Aztreonam: Escherichia coli, Klebsiella pneumoniae, Klebsiella aerogenes, Klebsiella oxytoca
- 3. Cefazolin: Escherichia coli, Klebsiella pneumoniae, Klebsiella variicola
- 4. Ceftazidime: Acinetobacter spp. (other than Acinetobacter ursingii), Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella variicola, Klebsiella pneumoniae, Pseudomonas aeruginosa
- 5. Ertapenem: Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Klebsiella oxytoca
- Trimethoprim-Sulfamethoxazole: Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, 6. Klebsiella variicola
- 7. Amikacin: Acinetobacter spp., Escherichia coli, Klebsiella pneumoniae, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella variicola, Pseudomonas aeruqinosa
- 8. Cefepime: Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Pseudomonas aeruginosa
- 9. Ceftazidime-avibactam: Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca
- 10. Gentamicin: Escherichia coli, Klebsiella pneumoniae, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella variicola, Pseudomonas aeruginosa
- 11. Levofloxacin: Escherichia coli, Klebsiella pneumoniae, Klebsiella derogenes, Klebsiella oxytoca, Pseudomonas aeruginosa
- 12. Meropenem: Acinetobacter spp., Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Pseudomonas aeruginosa
- 13. Meropenem-vaborbactam: Escherichia coli, Klebsiella pneumoniae, Klebsiella aerogenes, Klebsiella oxytoca
- 14. Piperacillin-tazobactam: Acinetobacter spp., Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa

# 5. Substantial Equivalence

This submission is an addition of claims to the K211815 and does not impact the safety or effectiveness of the LifeScale AST system.

| Device &<br>Predicate<br>Device(s): | New Device<br>Affinity Biosensors Lifescale Gram Negative<br>Kit (LSGN) with the LifeScale AST system | K211815<br>Predicate Device<br>Affinity Biosensors Lifescale Gram Negative<br>Kit (LSGN) with the LifeScale AST system | Antimicrobial Agents | |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------|----------------------|-------------------------------|
| Device Trade<br>Name | Lifescale Gram Negative Kit (LSGN) with the<br>LifeScale AST system | Lifescale Gram Negative Kit (LSGN) with the<br>LifeScale AST system | | Amikacin |
| General Device Similarities | | | | Cefepime |
| Intended<br>Use/Indications<br>for Use | The LifeScale AST system is a multiplexed <i>in vitro</i><br>diagnostic test that uses a microfluidic sensor and<br>resonant frequency to calculate organism | Same | | Ceftazidime-avibactam |
| concentration and/or mass distribution for<br>quantitative antimicrobial susceptibility testing<br>(AST). Testing is performed directly on blood<br>cultures signaled as positive by a continuous<br>monitoring blood culture system and confirmed by<br>Gram stain. The LifeScale AST system does not<br>provide organism identification and is not indicated<br>for use with polymicrobial samples. Interpretive<br>results (Susceptible/Intermediate/Susceptible-<br>dose dependent/Resistant) are provided for<br>specific drug/organism combinations. Results are<br>intended to be used in conjunction with other<br>clinical and laboratory findings. Standard<br>laboratory protocols for processing positive blood<br>cultures should be followed to ensure availability of<br>isolates for supplemental testing as needed.<br>Additionally, subculture of positive blood culture is<br>necessary for the susceptibility testing of organisms<br>present in polymicrobial samples, for testing<br>antimicrobial agents and species not indicated for<br>testing with the device, for epidemiologic testing<br>and for recovery of organisms present in microbial<br>samples.<br>The LifeScale Gram Negative Kit (LSGN) is intended<br>for use with the LifeScale AST system for <i>in vitro</i><br>testing of positive blood culture samples confirmed<br>by Gram stain as containing gram-negative bacilli. | | | | Gentamicin |
| Sample | Blood cultures are signaled as positive by a<br>continuous monitoring blood culture system. | Same | | Levofloxacin |
| Inoculation<br>Method | Automated | Same | | Meropenem |
| Read Method | Automated | Same | | Meropenem-vaborbactam |
| Results | Report results as a minimum inhibitory<br>concentration (MIC) and categorical<br>interpretation (S, I/SDD, R) | Same | | Piperacillin-tazobactam |
| Sample Prep | Centrifugation and pipetting of sample. | Same | | Ampicillin |
| Inoculation<br>Method | Automated | Same | | Aztreonam |
| IVD Functions | AST | Same | | Cefazolin |
| Technology | Microfluidic and resonant frequency to<br>calculate organism concentration and/or mass<br>distribution | Same | | Ceftazidime |
| Organisms<br>Tested | Gram-negative bacilli | Same | | Ertapenem |
| General Device Characteristic Differences | | | | Trimethoprim-sulfamethoxazole |

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# 6. Performance Characteristics

## Comparison Study

A comparison study was conducted to evaluate the performance of the LifeScale Gram Negative Kit (LSGN) with the LifeScale AST system in testing prospective clinical blood cultures confirmed positive by Gram Stain for Gram-negative bacilli. This study encompassed testing both prospective blood cultures (PBCs) and blood cultures contrived using isolates chosen to generate data required to fulfill intended use claims. All LifeScale AST sample results were compared to the reference Broth Microdilution (BMD). Each sample submitted for BMD testing was assigned a unique Trial ID, and LifeScale results were kept blinded to prevent bias. Performance was evaluated by comparing quantitative (MIC) and qualitative (S/I/SDD/R) AST results generated by the LifeScale AST System with those of the reference BMD.

Prospective PBCs consistent with the inclusion criteria were enrolled and tested at 6 US Clinical sites. For testing of prospective samples, organism ID was performed using an FDA-cleared direct from positive blood culture ID system. Testing was performed on the LifeScale AST System in accordance with the indications for use. PBC bottles were sub-cultured onto Tryptic Soy Agar supplemented with 5% Sheep Blood panels (BAP) and MacConkey Agar panels (MAC) incubated for 18-24 hours and examined for purity and colony morphology. If more than one colony type was observed, each organism was isolated for purity. All organisms isolated were identified using matrix-assisted laser desorption/ionization (MALD). Polymicrobial samples were withdrawn from the study. ID results generated using a direct from Blood Culture ID system and/or MALDI were entered into the LifeScale AST System, and a final MIC/SIR result was generated using the final LifeScale AST System software. If there was a discordant organism identification between MALDI and a Direct from Blood Culture system, MALDI ID was considered the organism's final identification.

Contrived samples were prepared from frozen isolates supplied by Affinity Biosensors, or they were prepared from contemporary isolates collected by the laboratory and agreed upon by Affinity for study inclusion. Blood cultures with the required amount of blood were spiked with isolated organisms and incubated in the blood culture system. When flagged as positive blood culture was tested on the LifeScale AST system in accordance with manufacturer's instructions for use. The PBC was sub-cultured to confirm purity. If a mixed (contaminated) culture was observed, a fresh contrived sample was prepared and tested.

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All LifeScale system testing was performed within 12 hours of the blood culture bottle being flagged as positive. LifeScale panels were read upon system confirmation of growth. Positive growth was determined automatically by the LifeScale AST system as part of the reading process. If the panel was incubated offline, it would be placed on the LifeScale system to be read. To generate the final AST report, the organism ID was entered into LifeScale AST System. The LifeScale AST System software generated the final AST results (MIC and S/I/SDD/R).

Reference testing was performed on all enrolled samples in triplicate. Testing was done in accordance with the reference protocol and was performed at two trial sites shipped isolates on transport media from the PBC purity panel following verification of pure culture. Samples contrived from laboratory stock underwent organism identification using MALDI prior to the reference site for testing. Reference testing was performed in triplicate. The procedure for Broth Microdilution reference testing follows CLSI guidance (CLSI M07).

The performance of the LifeScale AST system with the LSGN Kit was compared to the FDA-recognized reference BMD method for determining quantitative (MIC) AST results direct from Gram-negative positive blood cultures. Acceptable clinical performance was assessed across the following parameters for each antimicrobial agent on the LSGN panel; Essential Agreement (EA), Category Agreement (CA), Essential Agreement of evaluable results (Evaluable EA), Very Major Discrepancy (VMJ), Major Discrepancy (MAJ), Minor Discrepancy (MIN), Growth Failure Rate. For drug/organism group combinations where the susceptible dose-dependent category is recognized in place of the intermediate category, any errors that were observed with this category were designated as minor errors. Assessment of categorical agreement (Susceptible/ Susceptible-Dose Dependent/Intermediate/Resistant, S/SDD/I/R) was conducted utilizing FDA breakpoints (Antimicrobial Susceptibility Test Interpretive Criteria/STIC) and CLSI M100 guidelines, if applicable.

## Exclusion Data

## Summary of LifeScale LSGN AST Tests Initiated and Failed to Report a Result

The provided table summarizes tests initiated on the LifeScale AST system and the reasons for exclusion or incomplete results during clinical, and quality control (QC) phases. Out of 6164 tests initiated:

Plate Failures (0.32%): This category includes issues such as being unable to verify positive controls, sensor clogs detected, and the system being unable to calculate MIC.

Growth Failures (0.37%): These failures occurred due to issues related to growth during testing.

LifeScale Failures (1.12%): This category involves failures directly attributable to the LifeScale system, including software and hardware failures.

Other Reasons (0.57%): This includes a variety of reasons such as operator error, incubation time exceeding 8 hours, user cancellation, and protocol errors.

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The total percentage of tests excluded or incomplete is 2.38%, with clinical tests accounting for 0.31%, analytical tests for 1.83%, and QC tests for 0.24%.

Upon initiation of any test on the LifeScale system, results were available 97.62% (6017/6164) of the time.

| Reason for Exclusion/Incomplete Test | Clinical | Analytical | QC | Overall |
|--------------------------------------|----------------|------------------|-----------------|------------------|
| Plate Failures* | [5/986] 0.51% | [15/3307] 0.45% | [0/1871] 0.00% | [20/6164] 0.32% |
| Growth Failures | [6/986] 0.61% | [17/3307] 0.51% | [0/1871] 0.00% | [23/6164] 0.37% |
| LifeScale Failures** | [4/986] 0.41% | [50/3307] 1.51% | [15/1871] 0.80% | [69/6164] 1.12% |
| Other Reasons*** | [4/986] 0.41% | [31/3307] 0.94% | [0/1871] 0.00% | [35/6164] 0.57% |
| Total Excluded/Incomplete Tests | [19/986] 1.93% | [113/3307] 3.42% | [15/1871] 0.80% | [147/6164] 2.38% |

Table 2. Summary of LifeScale LSGN AST tests initiated and failed to report a result

*Plate Failures include: unable to verify positive controls, sensor cloq detected, system unable to calculate MIC

**LifeScale Failures include: LifeScale system software and hardware failures

***Other Reasons include: operator error, incubation time greater than 8 hours, user canceled, protocol error

## Clinical Performance Data

Overall AST performance for the LifeScale LSGN Kit with the LifeScale AST System was evaluated with 8 additional antimicrobials, and an overview of the overall performance is presented in Table 4, below.

| Total<br>Evaluated | No. EA | EA% | No.<br>Eval<br>Tot | No.<br>Eval<br>EA | Eval EA% | No. CA | CA% | No. R | No. S | #MIN<br>(MIN%) | #MAJ<br>(MAJ%) | #VMJ<br>(VMJ%) |
|---------------------------------------------------------------------------------------------------------------------------|--------|--------|--------------------|-------------------|----------|--------|-------|-------|-------|----------------|----------------|----------------|
| Amikacin-Acinetobacter spp. [Breakpoints (μg/mL): ≤16 (S), 32 (I), ≥64 (R)] | | | | | | | | | | | | |
| 77 | 77 | 100.0% | 11 | 11 | 100.0% | 75 | 97.4% | 17 | 58 | 2 (2.60%) | 0 (0.00%) | 0 (0.00%) |
| aAmikacin- E. coli, K. aerogenes, K. oxytoca, K. pneumoniae, K. variicola [Breakpoints (μg/mL): ≤16 (S), 32 (I), ≥64 (R)] | | | | | | | | | | | | |
| 480 | 467 | 97.3% | 54 | 41 | 75.9% | 460 | 95.8% | 62 | 400 | 17 (3.54%) | 3 (0.75%) | 0 (0.00%) |
| aAmikacin-Pseudomonas aeruginosa [Breakpoints (μg/mL): ≤16 (S), 32 (I), ≥64 (R)] | | | | | | | | | | | | |
| 59 | 58 | 98.3% | 15 | 14 | 93.3% | 56 | 94.9% | 7 | 50 | 3 (5.08%) | 0 (0.00%) | 0 (0.00%) |
| aCefepime- E. coli, K. aerogenes, K. oxytoca, K. pneumoniae [Breakpoints (μg/mL): <2 (S), 4,8 (SDDb), ≥16 (R)] | | | | | | | | | | | | |
| 445 | 412 | 92.6% | 64 | 31 | 48.4% | 426 | 95.7% | 154 | 281 | 16 (3.60%) | 3 (1.07%) | 0 (0.00%) |
| Cefepime-Pseudomonas aeruginosa [Breakpoints (μg/mL): <8 (S), ≥16 (R)] | | | | | | | | | | | | |
| 101 | 94 | 93.1% | 78 | 71 | 91.0% | 85 | 84.2% | 29 | 72 | 0 (0.00%) | 13 (18.06%) | 3 (10.34%) |
| aCeftazidime-avibactam- E. coli, K. aerogenes, K. oxytoca [Breakpoints (μg/mL): ≤8/4 (S), ≥16/4 (R)] | | | | | | | | | | | | |
| 303 | 300 | 99.0% | 7 | 4 | 57.1% | 300 | 99.0% | 47 | 256 | 0 (0.00%) | 3 (1.17%) | 0 (0.00%) |
| aGentamicin- E. coli, K. aerogenes, K. oxytoca, K. pneumoniae, K. variicola [Breakpoints (μg/mL): <4 (S), 8 (I), >16 (R)] | | | | | | | | | | | | |

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| 480 | 474 | 98.8% | 55 | 49 | 89.1% | 469 | 97.7% | 126 | 352 | 8 | (1.67%) | (0.57%) | 1 | (0.79%) |
|----------------------------------------------------------------------------------------------------------------------------------------|-----|-------|----|----|-------|-----|-------|-----|-----|----|----------|---------|---|---------|
| aGentamicin- <i>Pseudomonas aeruginosa</i> [Breakpoints (µg/mL): ≤4 (S), 8 (I), ≥16 (R)] | | | | | | | | | | | | | | |
| 59 | 56 | 94.9% | 18 | 15 | 83.3% | 55 | 93.2% | 10 | 47 | 4 | (6.78%) | (0.00%) | 0 | (0.00%) |
| aLevofloxacin- <i>E. coli, K. aerogenes, K. oxytoca, K. pneumoniae</i> [Breakpoints (µg/mL): ≤0.5 (S), 1 (I), ≥2 (R)] | | | | | | | | | | | | | | |
| 437 | 429 | 98.2% | 58 | 50 | 86.2% | 422 | 96.6% | 154 | 267 | 15 | (3.43%) | (0.00%) | 0 | (0.00%) |
| Levofloxacin- <i>Pseudomonas aeruginosa</i> [Breakpoints (µg/mL): ≤1 (S), 2 (I), ≥4 (R)] | | | | | | | | | | | | | | |
| 101 | 97 | 96.0% | 40 | 36 | 90.0% | 89 | 88.1% | 26 | 69 | 12 | (11.88%) | (0.00%) | 0 | (0.00%) |
| Meropenem- <i>Acinetobacter</i> spp. [Breakpoints (µg/mL): ≤2 (S), 4 (I), ≥8 (R)] | | | | | | | | | | | | | | |
| 78 | 75 | 96.2% | 42 | 39 | 92.9% | 76 | 97.4% | 37 | 41 | 2 | (2.56%) | (0.00%) | 0 | (0.00%) |
| aMeropenem- <i>E. coli, K. oxytoca, K. pneumoniae</i> [Breakpoints (µg/mL): ≤1 (S), 2 (I), ≥4 (R)] | | | | | | | | | | | | | | |
| 392 | 359 | 91.6% | 62 | 29 | 46.8% | 379 | 96.7% | 123 | 264 | 8 | (2.04%) | (0.38%) | 4 | (3.25%) |
| aMeropenem- <i>Pseudomonas aeruginosa</i> [Breakpoints (µg/mL): ≤2 (S), 4 (I), ≥8 (R)] | | | | | | | | | | | | | | |
| 59 | 57 | 96.6% | 39 | 37 | 94.9% | 53 | 89.8% | 25 | 32 | 6 | (10.17%) | (0.00%) | 0 | (0.00%) |
| aMeropenem-vaborbactam- <i>E. coli, K. aerogenes, K. oxytoca, K. pneumoniae</i><br>[Breakpoints (µg/mL): ≤4/8 (S), 8/8 (I), ≥16/8 (R)] | | | | | | | | | | | | | | |
| 442 | 420 | 95.0% | 39 | 17 | 43.6% | 418 | 94.6% | 77 | 362 | 22 | (4.98%) | (0.55%) | 0 | (0.00%) |
| aPiperacillin-tazobactam- <i>Acinetobacter</i> spp. [Breakpoints (µg/mL): ≤16/4 (S), 32/4-64/4 (I), ≥128/4 (R)] | | | | | | | | | | | | | | |
| 89 | 82 | 92.1% | 23 | 16 | 69.6% | 84 | 94.4% | 66 | 22 | 5 | (5.62%) | (0.00%) | 0 | (0.00%) |
| aPiperacillin-tazobactam- <i>E.coli, K. pneumoniae</i> [Breakpoints (µg/mL): ≤8/4 (S), 16/4 (I), ≥32/4 (R)] | | | | | | | | | | | | | | |
| 391 | 355 | 90.8% | 67 | 31 | 46.3% | 360 | 92.1% | 198 | 189 | 25 | (6.38%) | (1.58%) | 3 | (1.52%) |
| Piperacillin-tazobactam- <i>Pseudomonas aeruginosa</i> [Breakpoints (µg/mL): ≤8/4 (S), 16/4 (SDDb), ≥32/4 (R)] | | | | | | | | | | | | | | |
| 185 | 174 | 94.1% | 59 | 48 | 81.4% | 173 | 93.5% | 67 | 112 | 10 | (5.41%) | (0.89%) | 1 | (1.49%) |

# Table 3. LifeScale LSGN performance: Interpretation of MIC results are based on FDA Susceptibility Test Interpretative Criteria (STIC) and the 34th edition of the CLSI M100

¶n the clinical study or in the Inoculum Density analytical study, the majority of drug/organism combinations tested with the LifeScale LSGN Kit showed MIC values equal to or at least one doubling dilution higher/lower than the reference method. Use caution when reporting drug resistance for any antimicrobial. The following drug/organism combinations showed high trending:

- Amikacin Acinetobacter spp., E. coli, K. aerogenes, K. pneumoniae, K. variicola, P. aeruqinosa
- Cefepime E. coli, K. aerogenes, K. oxytoca, K. pneumoniae
- Ceftazidime-avibactam K. aerogenes, K. oxytoca
- Gentamicin E. coli, K. pneumoniae, K. oxytoca, K. aerogenes, P. aeruginosa
- Levofloxacin K. pneumoniae, K. oxytoca, K. aerogenes

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- Meropenem Acinetobacter calcoaceticus species, Acinetobacter lwoffii, K. oxytoca, P. aeruginosa
- Meropenem-vaborbactam K. pneumoniae, K. oxytoca, K. aerogenes
- · Piperacillin-tazobactam E. coli, K. pneumoniae

The following drug/organism combinations showed low trending

- Ceftazidime-avibactam - E. coli
- . Piperacillin-tazobactam - A. baumannii
- Meropenem-vaborbactam - E. coli

bSDD- Susceptible dose-dependent.

## Amikacin (AMI)

A total of 616 samples were evaluated with Amikacin including 465 clinical (75.5%) and 151 challenge (24.5%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 97.7% and a CA of 95.9% with no VMJs (0%) and 3 MAJs (0.59%).

## Species-level performance

- A total of 77 Acinetobacter spp. samples were evaluated with Amikacin. The combined results from clinical and challenge testing demonstrated an EA of 97.4% with no VMJs (0%) and no MAJs (0%).
- . A total of 140 E. coli samples were evaluated with Amikacin. The combined results from clinical and challenge testing demonstrated an EA of 96.4% and a CA of 95.7% with no VMJs (0%) and 2 MAJs (1.79%).
- . A total of 52 K. aerogenes samples were evaluated with Amikacin. The combined results from clinical and challenge testing demonstrated an EA of 100% and a CA of 98.1% with no VMJs (0%) and no MAJs (0%).
- . A total of 111 K. oxytoca samples were evaluated with Amikacin. The combined results from clinical and challenge testing demonstrated an EA of 99.1% and a CA of 99.1% with no VMJs (0%) and 1 MAJs (0.95%).
- A total of 142 K. pneumoniae samples were evaluated with Amikacin. The combined results from clinical and challenge testing demonstrated an EA of 95.8% and a CA of 91.5% with no VMJs (0%) and no MAJs (0%).
- . A total of 35 K. variicola samples were evaluated with Amikacin. The combined results from clinical and challenge testing demonstrated an EA of 97.1% and a CA of 100% with no VMJs (0%) and no MAJs (0%).
- A total of 59 P. aeruginosa samples were evaluated with Amikacin. The combined results from clinical and challenge testing demonstrated an EA of 94.9% and a CA of 94.9% with 0 VMJs (0%) and 0 MAJ (0%).

# Cefepime (FEP)

A total of 546 samples were evaluated with Cefepime including 388 clinical (71.1%) and 158 challenge (28.9%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 92.7% and a CA of 93.3% with 3 VMJs (1.64%) and 5 MAJs (1.42%).

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## Species-level performance

- . A total of 139 E. coli samples were evaluated with Cefepime. The combined results from clinical and challenge testing demonstrated an EA of 94.2% and a CA of 97.1% with no VMJs (0%) and 1 MAJs (1.37%).
- . A total of 53 K. aerogenes samples were evaluated with Cefepime. The combined results from clinical and challenge testing demonstrated an EA of 96.2% and a CA of 96.2% with no VMJs (0%) and no MAJs (0%).
- . A total of 111 K. oxytoco samples were evaluated with Cefepime. The combined results from clinical and challenge testing demonstrated an EA of 92.8% and a CA of 92.8% with no VMJs (0%) and 1 MAJs (1.08%).
- . A total of 142 K. pneumoniae samples were evaluated with Cefepime. The combined results from clinical and challenge testing demonstrated an EA of 91.5% and a CA of 96.5% with no VMJs (0%) and 1 MAJs (1.39%).
- . A total of 101 P. aeruginosa samples were evaluated with Cefepime. The combined results from clinical and challenge testing demonstrated an EA of 93.1% and a CA of 84.2% with 3 VMJs (10.34%) and 13 MAJ (18.06%). Due to the lack of an intermediate breakpoint the MAJ rate can be adjusted to 2.78% since 11/13 MAJ discrepancies were in essential agreement to the reference method. Due to the high MAJ rate at 4 µg/mL the following limitation is proposed:
- For Cefepime, perform an alternative method of testing prior to reporting of results for P. о aeruginosa when the MIC is 4 µg/mL due to the occurrence of very major errors (3/29 resistant isolates, 10.34%).

# Ceftazidime-avibactam (AVI)

A total of 303 samples were evaluated with Ceftazidime-avibactam including 232 clinical (76.6%) and 71 challenge (23.4%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 99.0% and a CA of 99.0% with no VMJs (0. 0%) and 3 MAJs (1.17%).

# Species-level performance

- . A total of 53 K. aerogenes samples were evaluated with Ceftazidime-avibactam. The combined results from clinical and challenge testing demonstrated an EA of 96.2% and a CA of 94.3% with no VMJs (0%) and 3 MAJs (5.77%). Due to the lack of an intermediate breakpoint, the MAJ rate can be adjusted to 1.92% since 2/3 MAJ discrepancies were within essential agreement to the reference method.
- . A total of 111 K. oxytoca samples were evaluated with Ceftazidime-avibactam. The combined results from clinical and challenge testing demonstrated an EA of 99.1% and a CA of 100% with no VMJs (0%) and 0 MAJs (0%).

A total of 139 E. coli samples were evaluated with Ceftazidime-avibactam. The combined results from clinical and challenge testing demonstrated an EA of 100% with no VMIS (0%) and no MAJs (0%).

# Gentamicin (GEN)

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A total of 539 samples were evaluated with Gentamicin including 407 clinical (75.5%) and 132 challenge (24.5%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 98.3% and a CA of 97.2% with 1 VMJs (0.74%) and 2 MAJs (0.50%).

## Species-level performance

- . A total of 139 E. coli samples were evaluated with Gentamicin. The combined results from clinical and challenge testing demonstrated an EA of 99.3% and a CA of 98.6% with no VMJs (0%) and no MAJs (0%).
- A total of 53 K. aerogenes samples were evaluated with Gentamicin. The combined results from clinical and challenge testing demonstrated an EA of 100% and a CA of 100% with no VMJs (0%) and no MAJs (0%).
- . A total of 111 K. oxytoca samples were evaluated with Gentamicin. The combined results from clinical and challenge testing demonstrated an EA of 99.1% and a CA of 98.2% with no VMJs (0%) and 1 MAJs (1.01%).
- . A total of 142 K. pneumoniae samples were evaluated with Gentamicin. The combined results from clinical and challenge testing demonstrated an EA of 97.2% and a CA of 95.8% with 1 VMJs (1.96%) and 1 MAJs (1.10%).
- . A total of 35 K. variicola samples were evaluated with Gentamicin. The combined results from clinical and challenge testing demonstrated an EA of 100% and a CA of 97.1% with no VMJs (0%) and no MAJs (0%).
- . A total of 59 P. aeruginosa samples were evaluated with Gentamicin. The combined results from clinical and challenge testing demonstrated an EA of 94.9% and a CA of 93.2% with 0 VMJs (0%) and 0 MAJ (0%).

# Levofloxacin (LEVO)

A total of 496 samples were evaluated with Levofloxacin including 370 clinical (74.6%) and 126 challenge (25.4%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 97.6%…