The MicroScan Dried Gram-Negative MIC/Combo Panel is used to determine quantitative and qualitative antimicrobial agent susceptibility of colonies grown on solid media of rapidly growing aerobic and facultative anaerobic gram-negative bacilli. After inoculation, panels are incubated for 16-20 hours at 35°C ± 1°C in a non-CO2 incubator, and read either visually or with MicroScan instrumentation, according to the Package Insert.

This particular submission is for the addition of the antimicrobial aztreonam at concentrations of 0.5-64 µg/mL to the test panel. Testing is indicated for Enterobacterales and Pseudomonas aeruginosa, as recognized by the FDA Susceptibility Test Interpretive Criteria (STIC) webpage.

The MicroScan Dried Gram-Negative MIC/Combo Panels with Aztreonam (AZT) (0.5-64 µg/mL) has demonstrated acceptable performance with the following organisms:

Enterobacterales (Citrobacter freundii complex, Citrobacter koseri, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Morganella morganii, Yersinia enterocolitica)

Pseudomonas aeruginosa

Device Description

MicroScan Dried Gram-Negative MIC/Combo Panels are designed for use in determining quantitative and qualitative antimicrobial agent susceptibility of colonies grown on solid media of rapidly growing aerobic and facultative anaerobic gram-negative bacilli.

The principle of MicroScan panels with antimicrobial susceptibility tests are miniaturizations of the broth dilution susceptibility test that have been diluted in broth and dehydrated. Various antimicrobial agents are diluted in broth to concentrations bridging the range of clinical interest. Panels are rehydrated with water after inoculation with a standardized suspension of the organism. After incubation in a non-CO2 incubator for 16-20 hours, the minimum inhibitory concentration (MIC) for the test organism is read by determining the lowest antimicrobial concentration showing inhibition of growth.

This product is single-use and intended for laboratory professional use.

AI/ML Overview

The provided FDA 510(k) clearance letter pertains to an Antimicrobial Susceptibility Test (AST) system, specifically the MicroScan Dried Gram-Negative MIC/Combo Panels with Aztreonam. It is not an AI/ML medical device. Therefore, many of the requested criteria regarding AI-specific study design (like MRMC studies, number of experts for AI ground truth, training set details) are not applicable to this type of device and study.

However, I can extract the relevant acceptance criteria and performance data for this AST device based on the provided document.

Acceptance Criteria and Device Performance (for an AST System)

The study proves the device's performance through comparison with a CLSI (Clinical and Laboratory Standards Institute) frozen Reference Panel. The criteria primarily revolve around "Essential Agreement (EA)" and "Categorical Agreement (CA)" between the new device and the reference method.

1. Table of Acceptance Criteria and Reported Device Performance

Performance Metric	Acceptance Criteria (Implicit from FDA Guidance*)	Reported Device Performance (Aztreonam)	Relevant Organisms	Notes
Essential Agreement (EA)	Generally, >90% (based on "acceptable performance" for similar devices in FDA guidance)	91.0%	Enterobacterales	Refers to agreement within one doubling dilution of the reference MIC.
Essential Agreement (EA)	Generally, >90%	91.2%	Pseudomonas aeruginosa	Refers to agreement within one doubling dilution of the reference MIC.
Categorical Agreement (CA)	Generally, >90% (based on "acceptable performance")	93.1%	Enterobacterales	Refers to agreement in clinical categorization (Susceptible, Intermediate, Resistant).
Categorical Agreement (CA)	Generally, >90%	86.0%*	Pseudomonas aeruginosa	*Footnote states "Essential agreement of evaluable isolates 90.3% and most of the categorical discrepancies were minor errors," implying this was deemed acceptable despite being below 90% in raw number.
Reproducibility	Acceptable reproducibility and precision	Demonstrated acceptable reproducibility and precision	Aztreonam	Across different inoculum methods (Turbidity, Prompt) and instruments (autoSCAN-4, WalkAway).
Quality Control	Acceptable results for Quality Control	Demonstrated acceptable results	Aztreonam	Standard QC strains.

Note: The document implicitly refers to the "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA", dated August 28, 2009. This guidance typically defines the statistical acceptance criteria for EA and CA for AST systems. The document states the device "demonstrated substantially equivalent performance when compared with a CLSI frozen Reference Panel, as defined in the FDA document..." meeting "acceptable performance."

2. Sample Size Used for the Test Set and Data Provenance

The document mentions "external evaluations were conducted with contemporary and stock Efficacy isolates and stock Challenge strains."
Specific numerical sample sizes for the test set (number of isolates/strains) are not explicitly stated in the provided text.
Data Provenance: The document does not specify the country of origin. It indicates the use of "contemporary and stock Efficacy isolates and stock Challenge strains," which suggests a mix of clinical and laboratory strains. The study appears to be prospective in nature, as new data was generated for this specific submission to demonstrate performance against a reference standard.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

This is an AST system, not an AI/ML device requiring expert radiological annotation.
Ground Truth Establishment: The ground truth (reference MIC values and categorical interpretations) for the test set was established by a CLSI frozen Reference panel. This is a recognized standard method for AST device validation. The "experts" in this context are the established CLSI methodologies and laboratories that produce these reference panels, not individual human readers or annotators in the typical AI/ML sense.

4. Adjudication Method for the Test Set

Adjudication, as typically described (e.g., 2+1, 3+1), is not applicable here because the ground truth is established by a standardized laboratory method (CLSI frozen Reference panel), not by consensus among human experts annotating medical images. The comparison is objective, based on measured MIC values.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

No, an MRMC comparative effectiveness study was not done. This type of study is specific to diagnostic imaging devices where human readers interpret medical images with and without AI assistance.
This device is an in vitro diagnostic (IVD) antimicrobial susceptibility test system, where the output is a MIC value and a categorical interpretation for a bacterial isolate, not an image interpretation by a human observer.

6. If a Standalone (Algorithm Only Without Human-in-the Loop Performance) Was Done

This question is framed for AI/ML algorithms. While the device automation ("MicroScan instrumentation," "WalkAway instrument") is a component, the "standalone performance" here refers to the device's ability to accurately determine MIC and categorize susceptibility when compared to the CLSI reference method.
The study did evaluate the device's performance independently of human interpretation, as it explicitly states panels can be "read either visually or with MicroScan instrumentation." The reported EA and CA numbers reflect the system's performance, including automated reading where applicable.

7. The Type of Ground Truth Used

Reference Standard: The ground truth used was a CLSI frozen Reference Panel. This is considered the gold standard for comparing the performance of new antimicrobial susceptibility test devices. It provides "true" Minimum Inhibitory Concentration (MIC) values for the bacterial isolates against the antimicrobial agent.

8. The Sample Size for the Training Set

This is an IVD device, not an AI/ML system that undergoes a separate "training" phase with a large dataset in the sense of machine learning. The device's underlying "knowledge" is built into its design, chemistry, and reading algorithms (for automated methods).
Therefore, the concept of a "training set" as understood in AI/ML is not applicable to this device.

9. How the Ground Truth for the Training Set Was Established

As the concept of a "training set" as in AI/ML does not apply here, this point is not applicable. The device's development involved standard microbiological and analytical chemistry principles, validated against established reference methods.

Summary

FDA 510(k) Clearance Letter - MicroScan Dried Gram-Negative MIC/Combo Panels with Aztreonam

Page 1

July 18, 2025

Beckman Coulter, Inc.
Elaine Duncan
Staff Regulatory Affairs
1584 Enterprise Blvd.
West Sacramento, California 95691

Re: K250084
Trade/Device Name: MicroScan Dried Gram-Negative MIC/Combo Panels with Aztreonam (AZT) (0.5-64 µg/mL)
Regulation Number: 21 CFR 866.1640
Regulation Name: Antimicrobial Susceptibility Test Powder
Regulatory Class: Class II
Product Code: LTT, JWY, LRG, LTW
Dated: June 20, 2025
Received: June 20, 2025

Dear Elaine Duncan:

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.

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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K250084 - Elaine Duncan Page 2

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.

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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K250084 - Elaine Duncan Page 3

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 (DICE@fda.hhs.gov) or phone (1-800-638-2041 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)
K250084

Device Name
MicroScan Dried Gram-Negative MIC/Combo Panels with Aztreonam (AZT) (0.5-64 µg/mL)

Indications for Use (Describe)

The MicroScan Dried Gram-Negative MIC/Combo Panels with Aztreonam (AZT) (0.5-64 µg/mL) has demonstrated acceptable performance with the following organisms:

Enterobacterales (Citrobacter freundii complex, Citrobacter koseri, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Morganella morganii, Yersinia enterocolitica)

Pseudomonas aeruginosa

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)

CONTINUE ON A SEPARATE PAGE IF NEEDED.

This section applies only to requirements of the Paperwork Reduction Act of 1995.

DO NOT SEND YOUR COMPLETED FORM TO THE PRA STAFF EMAIL ADDRESS BELOW.

The burden time for this collection of information is estimated to average 79 hours per response, including the time to review instructions, search existing data sources, gather and maintain the data needed and complete and review the collection of information. Send comments regarding this burden estimate or any other aspect of this information collection, including suggestions for reducing this burden, to:

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510(k) Summary

510(k) Submission Information:

Submitter's Name: Beckman Coulter
Contact Person: Elaine Duncan, Staff Regulatory Affairs
Address: 1584 Enterprise Blvd., West Sacramento, CA 95691
Phone: 916-318-0652
Date prepared: July 11, 2025
Product Name: Microdilution Minimum Inhibitory Concentration (MIC) Panels
Trade Name: MicroScan Dried Gram-Negative MIC/Combo Panels with Aztreonam (AZT) (0.5 – 64 µg/mL)
Classification: 21 CFR 866.1640 Antimicrobial Susceptibility Test Powder; Class II
Product Code: LTT, JWY, LRG, LTW
510(k) Notification: Updated antimicrobial agent - Aztreonam
Predicate device: MicroScan Dried Gram-Negative MIC/Combo Panels Ceftazidime – (0.5 – 64 µg/mL) - (K202343)

510(k) Summary:

Device Description: MicroScan Dried Gram-Negative MIC/Combo Panels are designed for use in determining quantitative and qualitative antimicrobial agent susceptibility of colonies grown on solid media of rapidly growing aerobic and facultative anaerobic gram-negative bacilli.

This product is single-use and intended for laboratory professional use.

Intended Use: For Use with MicroScan Dried Gram-Negative MIC/Combo and Dried Gram-Negative Breakpoint Combo panels. MicroScan panels are designed for use in determining antimicrobial agent susceptibility and/or identification to the species level of aerobic and facultatively anaerobic gram-negative bacilli.

Indications for Use: The MicroScan Dried Gram-Negative MIC/Combo Panel is used to determine quantitative and qualitative antimicrobial agent susceptibility of colonies grown on solid media of rapidly growing aerobic and facultatively anaerobic gram-negative bacilli. After inoculation, panels are incubated for 16-20 hours at 35°C ± 1°C in a non-CO2 incubator, and read either visually or with MicroScan instrumentation, according to the Package Insert.

This particular submission is for the addition of the antimicrobial aztreonam at concentrations of 0.5 - 64 µg/mL to the test panel. Testing is indicated for Enterobacterales and Pseudomonas aeruginosa, as recognized by the FDA Susceptibility Test Interpretive Criteria (STIC) webpage.

The MicroScan Dried Gram-Negative MIC/Combo Panels with Aztreonam (Azt) (0.5 - 64 µg/mL) has demonstrated acceptable performance with the following organisms:

Enterobacterales (Citrobacter freundii complex, Citrobacter koseri, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Morganella morganii, Yersinia enterocolitica)

Pseudomonas aeruginosa

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Substantial Equivalence Information

The similarities and differences of the MicroScan Dried Gram Negative MIC/Combo Panels with Aztreonam (Azt) (0.5 – 64 µg/mL) compared to the predicate device, MicroScan Dried Gram-Positive MIC/Combo Panels with Ceftazidime – (K202343), are described in Table 1 below.

Table 1: Substantial Equivalence

Similarities

Item	Proposed MicroScan Dried Gram-Negative MIC/Combo Panels – Aztreonam	Predicate MicroScan Dried Gram-Negative MIC/Combo Panels – Ceftazidime (K202343)
Intended Use	Determination of susceptibility to Aztreonam with gram-negative bacteria	Determination of susceptibility to Ceftazidime with gram-negative bacteria
Technology	Overnight Microdilution MIC Susceptibility Tests	Same
Specimen	Isolated colonies from cultures	Same
Incubation Temperature	35º C ± 1 º C	Same
Incubation Atmosphere	Aerobic	Same
Incubation Time	16 – 20 hours	Same
Reading Method	Automated or Manual	Same

Differences

Item	Proposed MicroScan Dried Gram-Negative MIC/Combo Panels – Aztreonam	Predicate MicroScan Dried Gram-Negative MIC/Combo Panels – Ceftazidime (K202343)
Antimicrobial Agent	Dried Aztreonam 0.5 – 64 µg/mL	Dried Ceftazidime 0.5 – 64 µg/mL

Performance and Conclusion: The proposed MicroScan Dried Gram-Negative MIC/Combo Panel demonstrated substantially equivalent performance when compared with a CLSI frozen Reference Panel, as defined in the FDA document "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA", dated August 28, 2009. The Premarket Notification (510[k]) presents data in support of the MicroScan Dried Gram-Negative MIC/Combo Panel with Aztreonam.

The external evaluations were conducted with contemporary and stock Efficacy isolates and stock Challenge strains. The external evaluations were designed to confirm the acceptability of the proposed Dried Gram-Negative Panel by comparing its performance with a CLSI frozen Reference panel. The Dried Gram-Negative Panel inoculated with Prompt and read on the WalkAway instrument demonstrated acceptable performance with an Enterobacterales Essential Agreement (EA) of 91.0% and Categorical Agreement (CA) of 93.1%, and Pseudomonas aeruginosa Essential Agreement (EA) of 91.2% and Categorical Agreement (CA) of 86.0%* for Aztreonam when compared with the frozen Reference panel. *Essential agreement of evaluable isolates 90.3% and most of the categorical discrepancies were minor errors.

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Inoculum and instrument reproducibility testing demonstrated acceptable reproducibility and precision with Aztreonam, regardless of which inoculum method (i.e., Turbidity or Prompt), or instrument (autoSCAN-4 instrument or WalkAway system) was used.

Quality Control testing demonstrated acceptable results for Aztreonam.

Beckman Coulter, the stylized logo, and the Beckman Coulter product and service marks mentioned herein are trademarks or registered trademarks of Beckman Coulter, Inc. in the United States and other countries.

Regulation Number and Section

§ 866.1640 Antimicrobial susceptibility test powder.

(a)
Identification. An antimicrobial susceptibility test powder is a device that consists of an antimicrobial drug powder packaged in vials in specified amounts and intended for use in clinical laboratories for determining in vitro susceptibility of bacterial pathogens to these therapeutic agents. Test results are used to determine the antimicrobial agent of choice in the treatment of bacterial diseases.(b)
Classification. Class II (performance standards).