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

K251875 · Affinity Biosensors, LLC · SAN · Oct 27, 2025 · Microbiology

Device Facts

• Record ID: K251875
• Device Name: LifeScale Gram Negative Kit (LSGN) with the LifeScale AST system
• Applicant: Affinity Biosensors, LLC
• Product Code: SAN · Microbiology
• Decision Date: Oct 27, 2025
• 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/Susceptible-dose dependent/Intermediate/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.

Device Story

LifeScale AST system performs quantitative antimicrobial susceptibility testing (AST) directly from positive blood culture samples. System uses microfluidic sensor with vibrating microchannel to detect individual microorganisms in suspension; measures mass of organisms in presence and absence of antibiotics. Calculates minimum inhibitory concentrations (MICs) and provides categorical interpretations (S/I/SDD/R) based on FDA STIC breakpoints. Operated by laboratory personnel; requires user to input organism identification from a separate platform. Results used by clinicians to guide antimicrobial therapy. Benefits include faster AST results compared to traditional subculture-based methods, potentially improving patient outcomes by enabling timely targeted therapy.

Clinical Evidence

Clinical performance evaluated using 432 positive blood culture samples (240 contemporary, 106 stock, 86 challenge). Performance measured against CLSI broth microdilution reference method. Essential agreement (EA) and categorical agreement (CA) calculated. Most drug/organism combinations met performance criteria (EA ≥95%). Limitations added for specific drug/organism combinations where error rates were unacceptable or trending was observed. Trending analysis identified several combinations with MIC values higher than reference method.

Technological Characteristics

Microfluidic sensor with vibrating microchannel; resonant frequency mass measurement. Automated inoculation and reading. Software-based MIC calculation. Compatible with various blood culture bottle types (BD BACTEC, BacT/ALERT, VersaTREK). Sterilization and materials previously cleared in K211815.

Indications for Use

Indicated for Acinetobacter spp., Enterobacterales, Pseudomonas aeruginosa, and Salmonella spp. in positive blood cultures confirmed as gram-negative bacilli by Gram stain. Not for polymicrobial samples. Provides quantitative MICs and categorical interpretations for specific drug/organism combinations.

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 (K241324)

Submission Summary (Full Text)

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FDA U.S. FOOD & DRUG ADMINISTRATION

October 27, 2025

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

Re: K251875
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
Regulatory Class: Class II
Product Code: SAN, LON
Dated: September 25, 2025
Received: September 25, 2025

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

U.S. Food & Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993
www.fda.gov

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K251875 - Nicole Holliday
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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, 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 device, then 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 (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-safety-reporting-combination-products); good manufacturing practice requirements as set forth in the quality systems (QS) 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-devices/device-advice-comprehensive-regulatory-assistance/unique-device-identification-system-udi-system.

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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 803), please go to https://www.fda.gov/medical-devices/medical-device-safety/medical-device-reporting-mdr-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/medical-devices/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-devices/device-advice-comprehensive-regulatory-assistance/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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DEPARTMENT OF HEALTH AND HUMAN SERVICES
Food and Drug Administration
Indications for Use
Form Approved: OMB No. 0910-0120
Expiration Date: 07/31/2026
See PRA Statement below.

510(k) Number (if known)
K251875

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 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.

Testing is indicated for Acinetobacter spp., Enterobacterales, Pseudomonas aeruginosa, and Salmonella spp. as recognized by the FDA Susceptibility Test Interpretive Criteria (STIC). The LSGN Kit with LifeScale AST system has demonstrated acceptable performance with the following organisms :

- Amikacin: Acinetobacter spp. (A. baumannii complex, A. calcoaceticus, A. lwoffii, A. pittii, A. radioresistens, A. ursingii)
- Ampicillin: Enterobacterales (Escherichia coli, Proteus mirabilis), and Salmonella spp.
- Aztreonam: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa
- Cefazolin: Enterobacterales (Escherichia coli, Klebsiella pneumoniae, Klebsiella variicola
- Cefepime: Enterobacterales (Citrobacter freundii, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa
- Ceftazidime: Acinetobacter spp. (A. baumannii complex, A. calcoaceticus, A. lwoffii, A. pittii, A. radioresistens), Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Klebsiella variicola, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa
- Ceftazidime-avibactam: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Providencia rettgeri, Providencia stuartii, Serratia marcescens)
- Ertapenem: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Providencia rettgeri, Providencia stuartii, Serratia marcescens)
- Gentamicin: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Klebsiella variicola, Serratia marcescens)
- Levofloxacin: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa
- Meropenem: Acinetobacter spp. (A. baumannii complex, A. calcoaceticus, A. lwoffii, A. pittii, A. radioresistens, A. ursingii), Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli,

FORM FDA 3881 (8/23)
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PSC Publishing Services [phone]

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Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Serratia marcescens), and Pseudomonas aeruginosa

- Meropenem-vaborbactam: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Providencia rettgeri, Providencia stuartii, Serratia marcescens
- Piperacillin-tazobactam: Acinetobacter spp (A. baumannii complex), Enterobacterales (Citrobacter koseri, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa,
- Trimethoprim-sulfamethoxazole: Enterobacterales (Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella variicola, Morganella morganii, Proteus mirabilis, Proteus vulgaris)

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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Affinity Biosensors

LifeScale AST System

510(k) Submission

# K251875

# 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
Director of Clinical Studies
Affinity Biosensors
222 East Canon Perdido Street
Suite 101
Santa Barbara, California 93101
[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/K241324 LifeScale™ Gram Negative Kit (LSGN) with the LifeScale AST system

# Purpose for Submission:

i. To obtain a substantial equivalence determination for the addition of the following gram-negative non-fastidious organisms to the LifeScale Gram Negative Kit (LSGN) Kit: Amikacin, Ampicillin, Aztreonam, Cefazolin, Cefepime, Ceftazidime, Ceftazidime-avibactam, Ertapenem, Gentamicin, Levofloxacin, Meropenem, Meropenem-vaborbactam, Piperacillin-tazobactam, Trimethoprim-sulfamethoxazole. The LSGN Kit is used with the LifeScale AST system for testing positive blood culture samples containing gram-negative bacilli.

Page 1 of 39

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Affinity Biosensors
LifeScale AST System
510(k) Submission

# Antimicrobial/Organism Combinations with Less Prevalent Organisms

Amikacin: Acinetobacter spp., (A. baumannii complex, A. calcoaceticus, A. lwoffii, A. pittii, A. radioresistens, A. ursingii)

Ampicillin: Enterobacterales (Escherichia coli, Proteus mirabilis), and Salmonella spp.

Aztreonam: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa

Cefazolin: Enterobacterales (Escherichia coli, Klebsiella pneumoniae, Klebsiella variicola)

Cefepime: Enterobacterales (Citrobacter freundii, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa

Ceftazidime: Acinetobacter spp. (other than Acinetobacter ursingii), Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Klebsiella variicola, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa

Ceftazidime-avibactam: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Providencia rettgeri, Providencia stuartii, Serratia marcescens)

Ertapenem: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Providencia rettgeri, Providencia stuartii, Serratia marcescens)

Gentamicin: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Klebsiella variicola, Serratia marcescens)

Levofloxacin: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa

Meropenem: Acinetobacter spp., Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Serratia marcescens), and Pseudomonas aeruginosa

Meropenem-vaborbactam: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Providencia rettgeri, Providencia stuartii, Serratia marcescens)

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Affinity Biosensors

LifeScale AST System

510(k) Submission

Piperacillin-tazobactam: Acinetobacter spp., Enterobacterales (Citrobacter koseri, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa,

Trimethoprim-sulfamethoxazole: Enterobacterales (Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella variicola, Morganella morganii, Proteus mirabilis, Proteus vulgaris)

## Cleared Antimicrobial/Organism Combinations (K211815):

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

## Additional Claimed Antimicrobial/Organism Combinations (K241324):

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 aeruginosa
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 aeruginosa

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Affinity Biosensors

LifeScale AST System

510(k) Submission

ii. Limitation Removal/Update Breakpoints

Removal of limitations included in the cleared LifeScale LSGN Kit with the LifeScale AST system (K241324). See limitation Removal Report for data analysis.

| | Antimicrobial/Organism | Current Limitation | Corrective Action In K251875 Labeling |
| --- | --- | --- | --- |
| 2. | Ceftazidime-avibactam/K. pneumoniae | Perform an alternative method of testing prior to reporting results for the following antimicrobial/organism combination(s): Ceftazidime-avibactam/K. pneumoniae | Additional clinical testing and revised limitation |
| 3. | Aztreonam/P. aeruginosa | Perform an alternative method of testing prior to reporting results for the following antimicrobial/organism combination(s): Aztreonam/P. aeruginosa | Additional clinical testing and revised limitation |
| 4. | Cefepime/P. aeruginosa | Update Breakpoints
Current Limitation: Perform an alternate method of testing prior to reporting P.aeruginosa when the MIC is 4 μg/mL due to the occurrence of very major errors (3/29 resistant isolates, 10.34%). | Limitation Revision: Perform an alternate method of testing prior to reporting P.aeruginosa when the MIC is 4 μg/mL due to the occurrence of a very major error (1/21 resistant isolates error (4.7%). Updated FDA/CLSI Breakpoints and revised in labeling |
| 5. | Ceftazidime/P. aeruginosa | Update breakpoints
Current Limitation: Perform an alternative method of testing prior to reporting P. aeruginosa at MIC value of 16 μg/mL due to the occurrence of major errors (5/61 susceptible isolates, 8.2%) adjusted to 2 major errors (3.3%) due to a lack of an intermediate | Remove Limitation Updated FDA/CLSI Breakpoints and revised in labeling |

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Affinity Biosensors

LifeScale AST System

510(k) Submission

# 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-sulfamethoxazole | SXT | 0.25 | 8 |

# 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, susceptible dose dependent, 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

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Affinity Biosensors

LifeScale AST System

510(k) Submission

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. Polymicrobial 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/Susceptible-dose dependent/Intermediate/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.

### New Indications for Use:

Testing is indicated for Acinetobacter spp., Enterobacterales, Pseudomonas aeruginosa, and Salmonella spp. as recognized by the FDA Susceptibility Test Interpretive Criteria (STIC). The LSGN Kit with LifeScale AST system has demonstrated acceptable performance with the following organisms:

Amikacin: Acinetobacter spp. (A. baumannii complex, A. calcoaceticus, A. lwoffii, A. pittii, A. radioresistens, A. ursingii)

Ampicillin: Enterobacterales (Escherichia coli, Proteus mirabilis), and Salmonella spp.

Aztreonam: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa

Cefazolin: Enterobacterales (Escherichia coli, Klebsiella pneumoniae, Klebsiella variicola)

Cefepime: Enterobacterales (Citrobacter freundii, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa

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Ceftazidime: Acinetobacter spp. (A. baumannii complex, A. calcoaceticus, A. lwoffii, A. pittii, A. radioresistens), Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Klebsiella variicola, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa

Ceftazidime-avibactam: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Providencia rettgeri, Providencia stuartii, Serratia marcescens)

Ertapenem: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Providencia rettgeri, Providencia stuartii, Serratia marcescens)

Gentamicin: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Klebsiella variicola, Serratia marcescens)

Levofloxacin: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa

Meropenem: Acinetobacter spp. (A. baumannii complex, A. calcoaceticus, A. lwoffii, A. pittii, A. radioresistens, A. ursingii), Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Serratia marcescens), and Pseudomonas aeruginosa

Meropenem-vaborbactam: Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, Providencia rettgeri, Providencia stuartii, Serratia marcescens)

Piperacillin-tazobactam: Acinetobacter spp. (A. baumannii complex), Enterobacterales (Citrobacter koseri, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, Serratia marcescens), and Pseudomonas aeruginosa,

Trimethoprim-sulfamethoxazole: Enterobacterales (Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella variicola, Morganella morganii, Proteus mirabilis, Proteus vulgaris)

5. Substantial Equivalence

This submission is an addition of claims to the K211815/K241324 and does not impact the safety or effectiveness of the LifeScale AST system.

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| Device & Predicate Device(s): | New Device
Affinity Biosensors Lifescale Gram Negative Kit (LSGN) with the LifeScale AST system | K241324
Predicate Device
Affinity Biosensors Lifescale Gram Negative Kit (LSGN) with the LifeScale AST system |
| --- | --- | --- |
| Device Trade Name | Lifescale Gram Negative Kit (LSGN) with the LifeScale AST system | Lifescale Gram Negative Kit (LSGN) with the LifeScale AST system |
| General Device Similarities | | |
| Intended Use/Indications for 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.
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. | Same |
| Sample | Blood cultures are signaled as positive by a continuous monitoring blood culture system. | Same |
| Inoculation Method | Automated | Same |
| Read Method | Automated | Same |
| Results | Report results as a minimum inhibitory concentration (MIC) and categorical interpretation (S, I/SDD, R) | Same |

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| Sample Prep | Centrifugation and pipetting of sample. | Same |
| --- | --- | --- |
| Inoculation Method | Automated | Same |
| IVD Functions | AST | Same |
| Technology | Microfluidic and resonant frequency to calculate organism concentration and/or mass distribution | Same |
| | | |
| Antimicrobial Agents | Amikacin
Cefepime
Ceftazidime-avibactam
Gentamicin
Levofloxacin
Meropenem
Meropenem-vaborbactam
Piperacillin-tazobactam
Ampicillin
Aztreonam
Cefazolin
Ceftazidime
Ertapenem
Trimethoprim-sulfamethoxazole | Same |
| | | |
| Differences | | |
| Organisms Tested | Acinetobacter spp., Enterobacterales (Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Klebsiella variicola, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri Providencia stuartii, Serratia marcescens), Pseudomonas aeruginosa, and Salmonella spp. | Acinetobacter spp., Enterobacterales (Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Klebsiella variicola), and Pseudomonas aeruginosa |

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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 clinical blood cultures confirmed positive by Gram Stain for Gram-negative bacilli. This study encompassed testing positive blood cultures (PBCs) contrived using contemporary and stock 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/SDD/I/R) AST results generated by the LifeScale AST System with those of the reference BMD.

Positive Blood Cultures consistent with the inclusion criteria were enrolled and tested at 3 US Clinical sites. For testing 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 (MALDI). 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/stock 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, the positive blood culture was tested on the LifeScale AST system in accordance with manufacturer's instructions for use. The PBC was subcultured to confirm purity. If a mixed (contaminated) culture was observed, a fresh contrived sample was prepared and tested.

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/SDD/I/R).

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Reference testing was performed on all enrolled samples in triplicate. Testing was done in accordance with the reference protocol and was performed at one trial site. Clinical 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 shipping 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) was conducted utilizing FDA breakpoints (Antimicrobial Susceptibility Test Interpretive Criteria/STIC) and CLSI M100 guidelines, if applicable.

Table 2. Number of Samples Tested

| Sample Type | Total (% of Total) |
| --- | --- |
| Contemporary Isolates | 240 (55.56%) |
| Stock Isolates | 106 (24.54%) |
| Challenge Isolates | 86 (19.91%) |
| Grand Total | 432 (100.0%) |

## 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, analytical, and quality control (QC) phases. Out of 764 tests initiated:

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Plate Failures (0.0%): 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 (0.26%): These failures occurred due to issues related to growth during testing.

LifeScale Failures (1.18%): This category involves failures directly attributable to the LifeScale system, including software and hardware failures.

Other Reasons (4.19%): This includes a variety of reasons such as operator errors, incubation time exceeding 8 hours, user cancellation, and protocol errors.

The total percentage of tests excluded, or incomplete, is $5.63\%$ .

| Reason for Exclusion/Incomplete Test | Clinical /Challenge | QC | Overall |
| --- | --- | --- | --- |
| Plate Failures* | [0/432] | [0/332] | [0/764] |
| | 0.0% | 0.0% | 0.0% |
| Growth Failures | [0/432] | [2/332] | [2/764] |
| | 0.0% | 0.6% | 0.26% |
| LifeScale Failures** | [6/432] | [3/332] | [9/764] |
| | 1.39% | 0.9% | 1.18% |
| Other Reasons*** | [29/432] | [3/332] | [32/764] |
| | 6.71% | 0.9% | 4.19% |
| Total Excluded/Incomplete Tests | [35/432]8.1% | [8/332]2.41% | [43/764]5.63% |

*Plate Failures include: unable to verify positive controls, sensor clog 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

Table 3. Summary of LifeScale LSGN AST tests initiated and failed to report a result

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# Clinical Performance Data

This interim report for performance represents the available clinical data for less prevalent organisms only. Data related to current Indications for Use organisms cleared in K211815/K241324; limitation removal and updated breakpoints will be incorporated once the FDA has completed it's evaluation of submitted reports. A finalized comprehensive version of this report, including all approved data sets and updates, will be issued following FDA feedback and included in the IFU.

| Total Evaluated | No. EA | EA% | Eval Tot | No. Eval EA | Eval EA% | No. CA | CA% | No. R | No. S | #MIN (MIN%) | #MAJ (MAJ%) | #VMJ (VMJ%) |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| a.aAmpicillin - P. mirabilis
[Breakpoints (μg/mL): ≤8.0 (S),16, ≥32.0 (R)] | | | | | | | | | | | | |
| 55 | 54 | 98.2% | 2 | 1 | 50.0% | 55 | 100.0% | 15 | 40 | 0 (0.00%) | 0 (0.00%) | 0 (0.00%) |
| aAmpicillin-Salmonella spp.
[Breakpoints (μg/mL): ≤8.0 (S),16, ≥32.0 (R)] | | | | | | | | | | | | |
| 20 | 20 | 100% | 1 | 1 | 100% | 20 | 100% | 3 | 17 | 0 (100%) | 0 (100%) | 0 (100%) |
| a.aAztreonam – C. freundii, C. koseri, E. cloacae complex
M. morganii, P. mirabilis, P. vulgaris, P. rettgeri, P. stuartii, S. marcescens
[Breakpoints (μg/mL): ≤4.0 (S),8.0(I), ≥16.0 (R)] | | | | | | | | | | | | |
| 365 | 350 | 95.9% | 42 | 27 | 64.3% | 363 | 99.5% | 47 | 316 | 2 (0.55%) | 0 (0.00%) | 0 (0.00%) |
| a.aCefepime- C. freundii, E. cloacae complex,
M. morganii, P. mirabilis, P. vulgaris, P. rettgeri, P. stuartii, S. marcescens
[Breakpoints (μg/mL): ≤2 (S), 4,8 (SDD^{b}), ≥16 (R)] | | | | | | | | | | | | |
| 299 | 289 | 96.7% | 27 | 17 | 63.0% | 293 | 98.0% | 29 | 265 | 6 (2.01%) | 0 (0.00%) | 0 (0.00%) |
| a.aCeftazidime - C. freundii, C. koseri, E. cloacae complex, M.morganii, P.mirabilis, P.vulgaris, P.stuartii, S.marcescens
[Breakpoints (μg/mL): ≤4.0 (S), 8(I), ≥16.0 (R)] | | | | | | | | | | | | |

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| 346 | 327 | 94.5% | 37 | 18 | 48.6% | 336 | 97.1% | 54 | 286 | 9 (2.60%) | 0 (0.00%) | 1 (1.85%) |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| a,eCeftazidime-avibactam- C. freundii, C. koseri, E. cloacae complex, M. morganii, P. mirabilis, P. rettgeri, P. stuartii, S. marcescens
[Breakpoints (μg/mL): ≤8/4 (S), ≥16/4 (R)] | | | | | | | | | | | | |
| 337 | 332 | 98.5% | 9 | 4 | 44.4% | 337 | 100.0% | 20 | 317 | 0 (0.00%) | 0 (0.00%) | 0 (0.00%) |
| a,eErtapenem - C. freundii, C. koseri, E. cloacae complex, M. morganii, P. rettgeri, P. stuartii, S. marcescens
[Breakpoints (μg/mL): ≤0.5 (S), 1(I), ≥2.0 (R)] | | | | | | | | | | | | |
| 278 | 263 | 94.6% | 28 | 13 | 46.4% | 268 | 96.4% | 33 | 243 | 8 (2.88%) | 2 (0.82%) | 0 (0.00%) |
| a,eGentamicin- C. freundii, C. koseri, E. cloacae complex, S. marcescens
[Breakpoints (μg/mL): ≤2 (S), 4 (I), ≥8 (R)] | | | | | | | | | | | | |
| 206 | 205 | 99.5% | 10 | 9 | 90.0% | 202 | 98.1% | 22 | 182 | 4(1.94%) | 0(0.00%) | 0(0.00%) |
| aLevofloxacin- C. freundii, C. koseri, E. cloacae complex
M. morganii, P. mirabilis, P. vulgaris, P. rettgeri, P. stuartii, S. marcescens
[Breakpoints (μg/mL): ≤0.5 (S), 1 (I), ≥2 (R)] | | | | | | | | | | | | |
| 371 | 359 | 96.8% | 79 | 67 | 84.8% | 348 | 93.8% | 73 | 284 | 22 (5.93%) | 1 (0.35%) | 0 (0.00%) |
| a,eMeropenem- C. freundii, C. koseri, E. cloacae complex, P. mirabilis, S. marcescens
[Breakpoints (μg/mL): ≤1 (S), 2 (I), ≥4 (R)] | | | | | | | | | | | | |
| 261 | 246 | 94.3% | 23 | 8 | 34.8% | 257 | 98.5% | 25 | 234 | 4 (1.53%) | 0 (0.00%) | 0 (0.00%) |
| a,eMeropenem-vaborbactam- C. freundii, C. koseri, E. cloacae complex, M. morganii, P. mirabilis, P. rettgeri, P. stuartii, S. marcescens
[Breakpoints (μg/mL): ≤4/8 (S), 8/8 (I), ≥16/8 (R)] | | | | | | | | | | | | |

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| 339 | 326 | 96.2% | 17 | 4 | 23.5% | 332 | 97.9% | 17 | 319 | 7 (2.06%) | 0 (0.00%) | 0 (0.00%) |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| a,ePiperacillin-tazobactam-C.koseri, P.mirabilis, P.vulgaris, P.rettgeri, P.stuartii, S.marcescens [Breakpoints (μg/mL): ≤8/4 (S), 16/4 (I), ≥32/4 (R)] | | | | | | | | | | | | |
| 242 | 232 | 95.9% | 26 | 16 | 61.5% | 229 | 94.6% | 20 | 220 | 10 (4.13%) | 3 (1.36%) | 0 (0.00%) |
| a,eTrimethoprim-sulfamethoxazole - E. cloacae complex, M. morganii P. mirabilis, P. vulgaris [Breakpoints (μg/mL): ≤2.0 (S), ≥4.0 (R)] | | | | | | | | | | | | |
| 165 | 163 | 98.8% | 6 | 4 | 66.7% | 164 | 99.4% | 49 | 116 | 0 (0.00%) | 0 (0.00%) | 1 (2.04%) |

Table 4. LifeScale LSGN performance: Interpretation of MIC results are based on FDA Susceptibility Test Interpretative Criteria (STIC) and the 35th edition of the CLSI M100

aIn the clinical study, the majority of drug/organism combinations tested with the LifeScale LSGN with the LifeScale AST system showed MIC values equal to or at least one doubling dilution higher than the reference method. Use caution when reporting drug resistance for any antimicrobial. The following drug/organism combinations showed high trending:

# Trending

Analysis of trending in the clinical study indicated that LifeScale Gram Negative Kit (LSGN) MIC values for the following antimicrobial/organism combinations tended to be at least one doubling dilution higher than the reference MIC value:

Ampicillin - E. coli, Proteus mirabilis and Salmonella species

Amikacin - Acinetobacter spp.

Aztreonam - E. coli, K. aerogenes, K. oxytoca, Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Enterobacter hormaechei, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, and Serratia marcescens

Cefazolin - K. pneumoniae

Cefepime - E. coli, K. aerogenes, K. oxytoca, K. pneumoniae, Citrobacter freundii, Enterobacter cloacae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia stuartii, and Serratia marcescens

Ceftazidime - E. coli, K. aerogenes, K. variicola, A. baumannii, P. aeruginosa, Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Enterobacter hormaechei, Proteus mirabilis, Proteus vulgaris, Providencia stuartii, and Serratia marcescens

Ceftazidime-avibactam - K. aerogenes, K. oxytoca, Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Morganella morganii, Proteus mirabilis, and Serratia marcescens

Ertapenem - E. coli, K. aerogenes, K. oxytoca, K. pneumoniae, Citrobacter freundii, Enterobacter cloacae complex, Morganella morganii, and Serratia marcescens

Gentamicin - E. coli, K. pneumoniae, K. oxytoca, K. aerogenes, and Serratia marcescens

Levofloxacin - K. pneumoniae, K. oxytoca, K. aerogenes, Citrobacter freundii, Enterobacter cloacae complex, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, and Serratia marcescens

Meropenem - K. oxytoca, P. aeruginosa, Citrobacter koseri, Proteus mirabilis, Serratia marcescens

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Meropenem-vaborbactam - K. pneumoniae, K. oxytoca, K. aerogenes, Citrobacter freundii, Enterobacter cloacae complex
Piperacillin-tazobactam – A.baumannii, K. pneumoniae, Citrobacter koseri, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, and Serratia marcescens
Trimethoprim-sulfamethoxazole - E. coli, K. aerogenes, K. variicola, and Proteus mirabilis

The following drug/organism combinations showed low trending:

1. Ceftazidime-M.morganii
2. Meropenem-vaborbactam – C.koseri and M.morganii
3. Trimethoprim-sulfamethoxazole-E.cloacae complex

${}^{a}$ Some species within the Enterobacterales had mostly off-scale results due to current epidemiology and /or device design

## Ampicillin (AMP)

A total of 75 samples were evaluated with Ampicillin including 63 clinical (84.0%) and 12 challenge (16.0%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 98.7% and a CA of 100% with 0 VMJs (0.0%) and 0 MAJs (0.0%).

## Species-level performance

- A total of 55 Proteus mirabilis samples were evaluated with Ampicillin. The combined results from clinical and challenge testing demonstrated an EA of 98.2% and a CA of 100% with no VMJs (0%) and 0 MAJs (0%).
- A total of 20 Salmonella spp. samples were evaluated with Ampicillin. 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%).

## Conclusion

Performance for Ampicillin with Proteus mirabilis and Salmonella spp. is acceptable.

## Limitation(s)

N/A

## Aztreonam (AZT)

A total of 365 samples were evaluated with Aztreonam including 290 clinical (79.5%) and 75 challenge (20.5%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 95.9% and a CA of 99.5% with 0 VMJs (0.0%) and 0 MAJs (0.0%).

## Species-level performance

- A total of 44 Citrobacter freundii samples were evaluated with Aztreonam. The combined results from clinical and challenge testing demonstrated an EA of 95.5% and a CA of 100% with no VMJs (0%) and 0 MAJs (0%).
- A total of 66 Citrobacter koseri samples were evaluated with Aztreonam. The combined results from clinical and challenge testing demonstrated an EA of 98.5% and a CA of 100% with no VMJs (0%) and no MAJs (0%).

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- A total of 42 Enterobacter cloacae complex samples were evaluated with Aztreonam. The combined results from clinical and challenge testing demonstrated an EA of 97.6% and a CA of 100% with no VMJs (0%) and no MAJs (0%).
- A total of 41 Morganella morganii samples were evaluated with Aztreonam. The combined results from clinical and challenge testing demonstrated an EA of 95.1% and a CA of 100% with no VMJs (0%) and no MAJs (0%).
- A total of 55 Proteus mirabilis samples were evaluated with Aztreonam. The combined results from clinical and challenge testing demonstrated an EA of 92.7% and a CA of 98.2% with no VMJs (0%) and no MAJs (0%).
- A total of 28 Proteus vulgaris samples were evaluated with Aztreonam. The combined results from clinical and challenge testing demonstrated an EA of 89.3% and a CA of 100% with no VMJs (0%) and no MAJs (0%).
- A total of 22 Providencia rettgeri samples were evaluated with Aztreonam. The combined results from clinical and challenge testing demonstrated an EA of 95.2% and a CA of 100% with no VMJs (0%) and no MAJs (0%).
- A total of 14 Providencia stuartii samples were evaluated with Aztreonam. 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 53 Serratia marcescens samples were evaluated with Aztreonam. The combined results from clinical and challenge testing demonstrated an EA of 98.1% and a CA of 98.1% with no VMJs (0%) and no MAJs (0%).

Conclusion

Performance for Aztreonam with Enterobacter cloacae complex, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, and Serratia marcescens is acceptable.

Limitation(s)

N/A

Cefepime (FEP)

A total of 299 samples were evaluated with Cefepime including 232 clinical (77.6%) and 67 challenge (22.4%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 96.7% and a CA of 98.0% with 0 VMJs (0.0%) and 0 MAJs (0.0%).

Species-level performance

- A total of 44 Citrobacter freundii samples were evaluated with Cefepime. The combined results from clinical and challenge testing demonstrated an EA of 90.0% and a CA of 95.5% with no VMJs (0%) and 0 MAJs (0%).

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- A total of 42 Enterobacter cloacae complex samples were evaluated with Cefepime. The combined results from clinical and challenge testing demonstrated an EA of 100% and a CA of 97.6% with no VMJs (0%) and no MAJs (0%).
- A total of 40 Morganella morganii samples were evaluated with Cefepime. The combined results from clinical and challenge testing demonstrated an EA of 92.5% and a CA of 92.5% with no VMJs (0%) and no MAJs (0%).
- A total of 55 Proteus mirabilis samples were evaluated with Cefepime. 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 28 Proteus vulgaris samples were evaluated with Cefepime. 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 22 Providencia rettgeri samples were evaluated with Cefepime. 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 15 Providencia stuartii samples were evaluated with Cefepime. 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 53 Serratia marcescens samples were evaluated with Cefepime. The combined results from clinical and challenge testing demonstrated an EA of 94.3% and a CA of 100% with no VMJs (0%) and no MAJs (0%).

Conclusion

Performance for Cefepime with Citrobacter freundii, Enterobacter cloacae, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, and Serratia marcescens are acceptable.

Limitation(s)

N/A

Ceftazidime (TAZ)

A total of 346 samples were evaluated with Ceftazidime including 272 clinical (78.6%) and 74 challenge (21.4%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 94.5% and a CA of 97.1% with 1 VMJs (1.85%) and 0 MAJs (0.0%).

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## Species-level performance

- A total of 44 *Citrobacter freundii* samples were evaluated with Ceftazidime. The combined results from clinical and challenge testing demonstrated an EA of 90.9% and a CA of 100% with no VMJs (0%) and 0 MAJs (0%).
- A total of 68 *Citrobacter koseri* samples were evaluated with Ceftazidime. The combined results from clinical and challenge testing demonstrated an EA of 94.1% and a CA of 97.1% with no VMJs (0%) and no MAJs (0%).
- A total of 43 *Enterobacter cloacae complex* samples were evaluated with Ceftazidime. The combined results from clinical and challenge testing demonstrated an EA of 90.7% and a CA of 97.7% with 0 VMJs (0%) and no MAJs (0%).
- A total of 41 *Morganella morganii* samples were evaluated with Ceftazidime. The combined results from clinical and challenge testing demonstrated an EA of 95.1% and a CA of 95.1% with 1 VMJs (16.67%) and no MAJs (0%).
- A total of 55 *Proteus mirabilis* samples were evaluated with Ceftazidime. The combined results from clinical and challenge testing demonstrated an EA of 98.2% and a CA of 98.2% with no VMJs (0%) and no MAJs (0%).
- A total of 28 *Proteus vulgaris* samples were evaluated with Ceftazidime. 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 14 *Providencia stuartii* samples were evaluated with Ceftazidime. The combined results from clinical and challenge testing demonstrated an EA of 92.9% and a CA of 92.9% with no VMJs (0%) and no MAJs (0%).
- A total of 53 *Serratia marcescens* samples were evaluated with Ceftazidime. The combined results from clinical and challenge testing demonstrated an EA of 94.3% and a CA of 94.3% with no VMJs (0%) and no MAJs (0%).

## Conclusion

Performance for Ceftazidime with *Citrobacter freundii*, *Citrobacter koseri*, *Enterobacter cloacae complex*, *Morganella morganii*, *Proteus mirabilis*, *Proteus vulgaris*, *Providencia stuartii*, and *Serratia marcescens* is acceptable.

*One very major error (VMJ) was observed with ceftazidime when testing Morganella morganii that resulted in an unacceptable VMJ rate (16.7%, 1/6). This was considered random due to the limited number of resistant Morganella morganii isolates tested.*

## Limitation(s)

Perform an alternative method of testing prior to reporting results for the following organism(s):

- *Providencia rettgeri*

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# Ceftazidime-avibactam (AVI)

A total of 337 samples were evaluated with Ceftazidime-avibactam including 273 clinical (81.1%) and 64 challenge (18.9%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 98.5% and a CA of 100% with no VMJs (0.0%) and 0 MAJs (0.0%).

# Species-level performance

- A total of 42 Citrobacter freundii samples were evaluated with Ceftazidime-avibactam. The combined results from clinical and challenge testing demonstrated an EA of 95.2% and a CA of 100% with no VMJs (0%) and 0 MAJs (0%).
- A total of 67 Citrobacter koseri samples were evaluated with Ceftazidime-avibactam. 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 42 Enterobacter cloacae complex samples were evaluated with Ceftazidime-avibactam. 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 42 Morganella morganii samples were evaluated with Ceftazidime-avibactam. 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 54 Proteus mirabilis samples were evaluated with Ceftazidime-avibactam. The combined results from clinical and challenge testing demonstrated an EA of 96.3% and a CA of 100% with no VMJs (0%) and no MAJs (0%).
- A total of 22 Providencia rettgeri samples were evaluated with Ceftazidime-avibactam. 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 15 Providencia stuartii samples were evaluated with Ceftazidime-avibactam. 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 53 Serratia marcescens samples were evaluated with Ceftazidime-avibactam. The combined results from clinical and challenge testing demonstrated an EA of 98.1% and a CA of 100% with no VMJs (0%) and no MAJs (0%).

# Conclusion

Performance for Ceftazidime-avibactam with Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Morganella morganii, Proteus mirabilis, Providencia rettgeri, Providencia stuartii, and Serratia marcescens is acceptable.

# Limitation(s)

N/A

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# Ertapenem (ETP)

A total of 278 samples were evaluated with Ertapenem including 224 clinical (80.6%) and 54 challenge (19.4%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 94.6% and a CA of 96.4% with no VMJs (0.0%) and 2 MAJs (0.82%).

# Species-level performance

- A total of 41 Citrobacter freundii samples were evaluated with Ertapenem. The combined results from clinical and challenge testing demonstrated an EA of 90.2% and a CA of 95.1% with no VMJs (0%) and 1 MAJs (2.86%).
- A total of 68 Citrobacter koseri samples were evaluated with Ertapenem. The combined results from clinical and challenge testing demonstrated an EA of 98.5% and a CA of 98.5% with no VMJs (0%) and no MAJs (0%).
- A total of 41 Enterobacter cloacae complex samples were evaluated with Ertapenem. The combined results from clinical and challenge testing demonstrated an EA of 92.7% and a CA of 90.2% with no VMJs (0%) and 1 MAJs (3.45%).
- A total of 39 Morganella morganii samples were evaluated with Ertapenem. The combined results from clinical and challenge testing demonstrated an EA of 97.4% and a CA of 97.4% with no VMJs (0%) and no MAJs (0%).
- A total of 23 Providencia rettgeri samples were evaluated with Ertapenem. 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 15 Providencia stuartii samples were evaluated with Ertapenem. 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 51 Serratia marcescens samples were evaluated with Ertapenem. The combined results from clinical and challenge testing demonstrated an EA of 90.2% and a CA of 96.1% with no VMJs (0%) and no MAJs (0%).

# Conclusion

Performance for Ertapenem with Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Morganella morganii, Providencia stuartii, Providencia rettgeri, and Serratia marcescens is acceptable.

# Limitation(s)

Perform an alternative method of testing prior to reporting results for the following organism(s):

- Proteus mirabilis
- Proteus vulgaris
- Enterobacter cloacae complex at MIC value of 2μg/mL due to the occurrence of 1 major error (1/29) susceptible isolates, (3.45%)

# Gentamicin (GEN)

A total of 206 samples were evaluated with Gentamicin including 166 clinical (80.6%) and 40 challenge (19.4%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 99.5% and a CA of 98.1% with 0 VMJs (0.0%) and 0 MAJs (0.0%).

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## Species-level performance

- A total of 44 *Citrobacter freundii* samples were evaluated with Gentamicin. The combined results from clinical and challenge testing demonstrated an EA of 100% and a CA of 97.7% with no VMJs (0%) and 0 MAJs (0.0%).
- A total of 66 *Citrobacter koseri* samples were evaluated with Gentamicin. The combined results from clinical and challenge testing demonstrated an EA of 100% and a CA of 98.5% with no VMJs (0%) and no MAJs (0%).
- A total of 43 *Enterobacter cloacae complex* 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 53 *Serratia marcescens* samples were evaluated with Gentamicin. The combined results from clinical and challenge testing demonstrated an EA of 98.1% and a CA of 96.2% with no VMJs (0%) and no MAJs (0%).

## Conclusion

Performance for Gentamicin with *Citrobacter freundii*, *Citrobacter koseri*, *Enterobacter cloacae*, and *Serratia marcescens* is acceptable.

## Limitation(s)

Perform an alternative method of testing prior to reporting results for the following organism(s):

- Proteus vulgaris
- Proteus mirabilis

## Levofloxacin (LEVO)

A total of 371 samples were evaluated with Levofloxacin including 285 clinical (76.8%) and 86 challenge (23.2%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 96.8% and a CA of 93.8% with 0 VMJs (0%) and 1 MAJs (0.35%).

## Species-level performance

- A total of 44 *Citrobacter freundii* samples were evaluated with Levofloxacin. The combined results from clinical and challenge testing demonstrated an EA of 97.7% and a CA of 88.6% with no VMJs (0%) and 1 MAJs (2.86%).
- A total of 68 *Citrobacter koseri* samples were evaluated with Levofloxacin. The combined results from clinical and challenge testing demonstrated an EA of 98.5% and a CA of 97.1% with no VMJs (0%) and no MAJs (0%).
- A total of 50 *Enterobacter cloacae complex* samples were evaluated with Levofloxacin. The combined results from clinical and challenge testing demonstrated an EA of 94.0% and a CA of 90.0% with no VMJs (0%) and no MAJs (0%).

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510(k) Submission

- A total of 41 Morganella morganii samples were evaluated with Levofloxacin. The combined results from clinical and challenge testing demonstrated an EA of 97.6% and a CA of 97.6% with no VMJs (0%) and no MAJs (0%).
- A total of 55 Proteus mirabilis samples were evaluated with Levofloxacin. The combined results from clinical and challenge testing demonstrated an EA of 90.9% and a CA of 96.4% with no VMJs (0%) and no MAJs (0%).
- A total of 29 Proteus vulgaris samples were evaluated with Levofloxacin. The combined results from clinical and challenge testing demonstrated an EA of 96.6% and a CA of 93.1% with no VMJs (0%) and no MAJs (0%).
- A total of 18 Providencia rettgeri samples were evaluated with Levofloxacin. The combined results from clinical and challenge testing demonstrated an EA of 100% and a CA of 88.9% with no VMJs (0%) and no MAJs (0%).
- A total of 13 Providencia stuartii samples were evaluated with Levofloxacin. 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 53 Serratia marcescens samples were evaluated with Levofloxacin. The combined results from clinical and challenge testing demonstrated an EA of 100% and a CA of 92.5% with no VMJs (0%) and no MAJs (0%).

## Conclusion

Performance for Levofloxacin with Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Morganella morganii, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, and Serratia marcescens is acceptable.

## Limitation(s)

N/A

## Meropenem (MERO)

A total of 261 samples were evaluated with Meropenem including 209 clinical (80.1%) and 52 challenge (19.9%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 94.3% and a CA of 98.5% with 0 VMJs (0.0%) and 0 MAJs (0.0%).

## Species-level performance

- A total of 44 Citrobacter freundii samples were evaluated with Meropenem. The combined results from clinical and challenge testing demonstrated an EA of 95.5% and a CA of 97.7% with no VMJs (0%) and 0 MAJs (0%).
- A total of 68 Citrobacter koseri samples were evaluated with Meropenem. The combined results from clinical and challenge testing demonstrated an EA of 94.1% and a CA of 98.5% with no VMJs (0%) and no MAJs (0%).

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- A total of 41 Enterobacter cloacae complex samples were evaluated with Meropenem. The combined results from clinical and challenge testing demonstrated an EA of 92.7% and a CA of 97.6% with no VMJs (0%) and no MAJs (0%).
- A total of 53 Proteus mirabilis samples were evaluated with Meropenem. The combined results from clinical and challenge testing demonstrated an EA of 90.9% and a CA of 98.2% with no VMJs (0%) and no MAJs (0%).
- A total of 55 Serratia marcescens samples were evaluated with Meropenem. The combined results from clinical and challenge testing demonstrated an EA of 98.1% and a CA of 100% with no VMJs (0%) and no MAJs (0%).

## Conclusion

Performance for Meropenem with Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Proteus mirabilis, and Serratia marcescens is acceptable.

## Limitation(s)

Perform an alternative method of testing prior to reporting results for the following organism(s):

- Morganella morganii
- Proteus vulgaris

## Meropenem-vaborbactam (MEV)

A total of 339 samples were evaluated with Meropenem-vaborbactam including 274 clinical (80.8%) and 65 challenge (19.2%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 96.2% and a CA of 97.9% with no VMJs (0%) and 0 MAJs (0.0%).

## Species-level performance

- A total of 44 Citrobacter freundii samples were evaluated with Meropenem-vaborbactam. The combined results from clinical and challenge testing demonstrated an EA of 93.2% and a CA of 97.7% with no VMJs (0%) and 0 MAJs (0%).
- A total of 68 Citrobacter koseri samples were evaluated with Meropenem-vaborbactam. The combined results from clinical and challenge testing demonstrated an EA of 97.1% and a CA of 97.1% with no VMJs (0%) and no MAJs (0%).
- A total of 42 Enterobacter cloacae complex samples were evaluated with Meropenem-vaborbactam. The combined results from clinical and challenge testing demonstrated an EA of 95.2% and a CA of 97.6% with no VMJs (0%) and no MAJs (0%).
- A total of 40 Morganella morganii samples were evaluated with Meropenem-vaborbactam. The combined results from clinical and challenge testing demonstrated an EA of 95.0% and a CA of 100% with no VMJs (0%) and no MAJs (0%).

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- A total of 55 Proteus mirabilis samples were evaluated with Meropenem-vaborbactam. The combined results from clinical and challenge testing demonstrated an EA of 94.5% and a CA of 96.4% with no VMJs (0%) and no MAJs (0%).
- A total of 22 Providencia rettgeri samples were evaluated with Meropenem-vaborbactam. The combined results from clinical and challenge testing demonstrated an EA of 100% and a CA of 95.5% with no VMJs (0%) and no MAJs (0%).
- A total of 15 Providencia stuartii samples were evaluated with Meropenem-vaborbactam. 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 53 Serratia marcescens samples were evaluated with Meropenem-vaborbactam. 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%).

Conclusion

Performance for Meropenem-vaborbactam with Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae, Morganella morganii, Proteus mirabilis, Providencia rettgeri, Providencia stuartii, and Serratia marcescens is acceptable.

Limitation(s)

N/A

Piperacillin-tazobactam (P/T)

A total of 242 samples were evaluated with Piperacillin-tazobactam including 194 clinical (80.2%) and 48 challenge (19.8%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 95.9% and a CA of 94.6% with 0 VMJs (0.0%) and 3 MAJs (1.36%).

Species-level performance

- A total of 68 Citrobacter koseri samples were evaluated with Piperacillin-tazobactam. The combined results from clinical and challenge testing demonstrated an EA of 94.1% and a CA of 91.2% with no VMJs (0.0%) and 1 MAJs (1.72%).
- A total of 55 Proteus mirabilis samples were evaluated with Piperacillin-tazobactam. The combined results from clinical and challenge testing demonstrated an EA of 98.2% and a CA of 98.2% with no VMJs (0%) and 1 MAJs (1.89%).
- A total of 29 Proteus vulgaris samples were evaluated with Piperacillin-tazobactam. The combined results from clinical and challenge testing demonstrated an EA of 96.6% and a CA of 96.6% with no VMJs (0%) and 1 MAJs (3.57%).

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- A total of 22 Providencia rettgeri samples were evaluated with Piperacillin-tazobactam. The combined results from clinical and challenge testing demonstrated an EA of 95.5% and a CA of 95.5% with no VMJs (0%) and no MAJs (0%).
- A total of 15 Providencia stuartii samples were evaluated with Piperacillin-tazobactam. The combined results from clinical and challenge testing demonstrated an EA of 100% and a CA of 93.3% with no VMJs (0%) and no MAJs (0%).
- A total of 53 Serratia marcescens samples were evaluated with Piperacillin-tazobactam. The combined results from clinical and challenge testing demonstrated an EA of 94.3% and a CA of 94.3% with no VMJs (0%) and no MAJs (0%).

## Conclusion

Performance for Piperacillin-tazobactam with Citrobacter koseri, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, and Serratia marcescens is acceptable.

## Limitation(s)

Perform an alternative method of testing prior to reporting results for the following organism(s):

- Morganella morganii
- Proteus vulgaris at MIC value of 32μg/mL due to the occurrence of 1 major error (1/28) susceptible isolates, (3.57%)

## Trimethoprim-sulfamethoxazole (SXT)

A total of 165 samples were evaluated with Trimethoprim-sulfamethoxazole including 122 clinical (73.9%) and 43 challenge (26.1%) samples. The combined results from clinical and challenge testing from all claimed species demonstrated an EA of 98.8% and a CA of 99.4% with 0 VMJs (0.0%) and 0 MAJs (0.0%).

## Species-level performance

- A total of 43 Enterobacter cloacae samples were evaluated with Trimethoprim-sulfamethoxazole. 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 54 Proteus mirabilis samples were evaluated with Trimethoprim-sulfamethoxazole. 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 28 Proteus vulgaris samples were evaluated with Trimethoprim-sulfamethoxazole. The combined results from clinical and challenge testing demonstrated an EA of 96.4% and a CA of 96.4% with no VMJs (0%) and no MAJs (0%).

## Conclusion

Performance for Trimethoprim-sulfamethoxazole with Enterobacter cloacae, Proteus mirabilis, Proteus vulgaris, is acceptable.

## Limitation(s)

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N/A

# Quality Control

Strains recommended by the FDA and CLSI and the LifeScale QC strain (Enterobacter cloacae ABGNQC1) were tested for each antimicrobial agent evaluated using the LifeScale AST System LSGN Panel and the CLSI Reference Broth Microdilution Method. The quality control (QC) strains tested were Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 700603, and Enterobacter cloacae ABGNQC1. The QC testing results for all antimicrobics on the LSGN panel are detailed in Tables 5-17.

QC <95% explanation: The observed QC errors could be associated with the frequency of subculturing which may cause a decline in viability leading to inconsistent performance. In all cases where QC were out of range, the subsequent repeat tests, performed with a fresh subculture were within range indicating that the system was functioning properly and the initial failures were not systemic. MCW and LACNY experienced sporadic QC outliers for Meropenem and Gentamicin. Overall, these findings reflect isolated occurrences tied to organism, rather than systemic issues with the LifeScale system or test performance.

In the previous submission K241324, LifeScale demonstrated robust QC performance with Meropenem achieving >98% within range results and Gentamicin at 100%. The few recent QC outliers observed were isolated and linked issues with strain integrity.

To prevent recurrence for future studies all sites will be reminded to follow subculturing schedules per the protocol, and QC organism handling procedures.

Amikacin

| QC Organism | Expected Range (μg/mL) | Conc. μg/mL | Reference Frequency | New Device Test Frequency | | |
| --- | --- | --- | --- | --- | --- | --- |
| | | Sites → | Ref Lab (ABIO) | ABIO | LACNY | MCW |
| | 8 – 32 | <=4 | | | | |

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| Enterobacter cloacae ABGNQC1 | | 8 | | 9 | 2 | 2 |
| --- | --- | --- | --- | --- | --- | --- |
| | | 16 | 18 | 15 | 23 | 17 |
| | | 32 | 10 | | 7 | 4 |
| | | 64 | | | 1 | |
| | | 128 | | | | |
| | | 256 | | | | |
| | | >256 | | | | |
| Total | | | 28/28 (100%) | 24/24 (100%) | 32/33 (97.0%) | 23/23 (100%) |

Table 5. LifeScale AST System QC MIC Distribution for Amikacin
Ampicillin

| QC Organism | Expected Range (μg/mL) | Conc. μg/mL | Reference Frequency | New Device Test Frequency | | |
| --- | --- | --- | --- | --- | --- | --- |
| | | Sites → | Ref Lab (ABIO) | ABIO | LACNY | MCW |
| Escherichia coli ATCC 25922 | <=2-8 | <=2 | 4 | 21 | 22 | 18 |
| | | 4 | 24 | 6 | 9 | 6 |
| | | 8 | 1 | | | |
| | | 16 | | | | |
| | | 32 | | | | |
| | | 64 | | | | |
| | | >64 | | | | |
| Total | | | 29/29 (100%) | 27/27 (100%) | 31/31 (100%) | 24/24 (100%) |

Table 6. LifeScale AST System QC MIC Distribution for Ampicillin
Aztreonam

| QC Organism | Expected Range (μg/mL) | Conc. μg/mL | Reference Frequency | New Device Test Frequency | | |
| --- | --- | --- | --- | --- | --- | --- |
| | | Sites → | aRef Lab (ABIO) | ABIO | LACNY | MCW |
| Pseudomonas aeruginosa ATCC 27853 | 2-8 | <=1 | 2 | | | |
| | | 2 | 4 | 20 | 26 | 24 |
| | | 4 | 25 | 3 | 6 | 1 |
| | | 8 | 5 | 1 | 1 | |
| | | 16 | | | | |
| | | 32 | | | | |

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| | | 64 | | | | 1 |
| --- | --- | --- | --- | --- | -…