The Liofilchem® MIC Test Strip (MTS) is a quantitative method intended for the in vitro determination of antimicrobial susceptibility of bacteria. MTS consists of specialized paper impregnated with a pre-defined concentration gradient of an antimicrobial agent, which is used to determine the minimum inhibitory concentration (MIC) in ug/mL of antimicrobial agents against bacteria as tested on agar media using overnight incubation and manual reading procedures.

The Tedizolid MTS at concentrations of 0.002-32 ug/mL should be interpreted at 16-20 hours of incubation.

The non-fastidious bacteria that have been shown to be active both clinically and in vitro against Tedizolid according to the FDA label are:

Staphylococcus aureus (including methicillin-resistant and methicillin susceptible isolates) Enterococcus faecalis

Device Description

MTS consists of specialized paper impregnated with a pre-defined concentration gradient of an antimicrobial agent, which is used to determine the minimum inhibitory concentration (MIC) in ug/mL of antimicrobial agents against bacteria as tested on agar media using overnight incubation and manual reading procedures.

AI/ML Overview

This document is a 510(k) premarket notification from the FDA for a medical device called the "Liofilchem MIC Test Strip (MTS), Tedizolid 0.002 - 32 µg/ml." This device is an Antimicrobial Susceptibility Test (AST) that determines the Minimum Inhibitory Concentration (MIC) of Tedizolid against certain bacteria.

The provided text does not contain the information requested for a detailed description of acceptance criteria and a study proving device performance as typically expected for imaging or AI/ML-based diagnostic devices (e.g., Sensitivity, Specificity, AUC, MRMC studies, expert adjudication, ground truth definition for a test set). Instead, it's a regulatory letter confirming substantial equivalence to a predicate device for an in-vitro diagnostic test.

The "acceptance criteria" for an AST device are typically established based on concordances with a reference method (e.g., CDC or CLSI reference broth microdilution) rather than the metrics for assessing imaging or AI/ML algorithms. The letter states the device is "substantially equivalent" to legally marketed predicate devices, meaning it meets the FDA's requirements for safety and effectiveness for its intended use, typically demonstrating comparable performance to the predicate.

Therefore, for aspects like "sample size used for the test set," "number of experts," "adjudication method," "MRMC study," "standalone performance," "type of ground truth," and "training set details," the information is not present in this regulatory letter because these are not concepts directly applicable to the type of device and regulatory review described.

What can be inferred or directly stated from the provided text regarding device performance relates to its clinical utility rather than an AI/ML or imaging-based diagnostic study.

Here's what can be extracted based on the document's content, and what cannot:

A table of acceptance criteria and the reported device performance:
- Acceptance Criteria (Inferred from 510(k) process for ASTs): The primary criteria for AST devices like this are typically substantial equivalence to a predicate device, demonstrated through acceptable categorical agreement (Susceptible, Intermediate, Resistant) and essential agreement (within +/- 1 dilution of the reference method) with a reference standard method (e.g., CLSI broth microdilution). The exact thresholds for these agreements are not in this document but are standard for AST 510(k) submissions.
- Reported Device Performance: The document states the device is "substantially equivalent" to predicate devices. It doesn't present raw performance data (e.g., specific agreement percentages) within this letter. It does state the device determines "minimum inhibitory concentration (MIC) in ug/mL of antimicrobial agents against bacteria as tested on agar media using overnight incubation and manual reading procedures."
- Clinically relevant information: The device is for Tedizolid (0.002-32 ug/mL) and should be interpreted at 16-20 hours of incubation. The bacteria shown to be active are Staphylococcus aureus (including MRSA and MSSA) and Enterococcus faecalis.
Sample size used for the test set and the data provenance:
- Not explicitly stated in the provided text. For AST devices, the test set would be a collection of bacterial isolates with known susceptibilities. The provenance (country, retrospective/prospective) is not mentioned.
Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- Not applicable/Not stated. Ground truth for ASTs is established by a reference laboratory method (e.g., Clinical and Laboratory Standards Institute (CLSI) broth microdilution) rather than expert human interpretation in the same way an imaging study would use radiologists.
Adjudication method (e.g., 2+1, 3+1, none) for the test set:
- Not applicable/Not stated. This concept is relevant for human expert-based ground truth establishment, not for a laboratory-based AST device.
If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:
- Not applicable. This device is a manual-read, in-vitro diagnostic test strip, not an AI-assisted imaging device. There are no human "readers" in the context of an MRMC study or AI assistance.
If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
- Not applicable. This is a physical test strip, not an algorithm. Its "standalone" performance would refer to its accuracy compared to a reference method, which is the basis of its substantial equivalence. The mechanism of reading is manual.
The type of ground truth used:
- Inferred: For AST devices, the ground truth is typically a reference antimicrobial susceptibility testing method, such as the CLSI broth microdilution method. This method provides the true MIC value against which the device's performance is compared for essential and categorical agreement.
The sample size for the training set:
- Not applicable/Not stated. This device is not an AI/ML algorithm that requires a "training set." Its design and performance are based on chemical principles and established microbiological methods.
How the ground truth for the training set was established:
- Not applicable. No training set for an AI/ML algorithm is involved.

In summary, the provided document is a regulatory approval letter for an in vitro diagnostic medical device (antimicrobial susceptibility test strip) that is manually read. It does not pertain to an AI/ML or imaging-based diagnostic device, and therefore the majority of the requested information (related to AI/ML study design, expert ground truth, MRMC studies, etc.) is not present and not relevant to this type of device. The core acceptance criteria for such a device would revolve around its agreement with established reference methods in microbiology, rather than expert interpretation or AI performance metrics.

Summary

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Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002

May 25, 2017

LIOFILCHEM S. R. L. c/o LAURA KOETH PRESIDENT, LABORATORY SPECIALISTS, INC. 1651-A CROSSINGS PARKWAY WESTLAKE OH 44145

Re: K170892

Trade/Device Name: Liofilchem MIC Test Strip (MTS), Tedizolid 0.002 - 32 µg/ml Regulation Number: 21 CFR 866.1640 Regulation Name: Antimicrobial susceptibility test powder Regulatory Class: II Product Code: JWY Dated: March 27, 2017 Received: March 28, 2017

Dear Ms. Koeth:

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 (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. 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.

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 Parts 801 and 809); medical device reporting (reporting of medical device-related adverse events) (21 CFR 803); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

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If you desire specific advice for your device on our labeling regulations (21 CFR Parts 801 and 809), please contact the Division of Industry and Consumer Education at its toll-free number (800) 638 2041 or (301) 796-7100 or at its Internet address

http://www.fda.gov/MedicalDevices/ResourcesforYou/Industry/default.htm. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to

http://www.fda.gov/MedicalDevices/Safety/ReportaProblem/default.htm for the CDRH's Office of Surveillance and Biometrics/Division of Postmarket Surveillance.

You may obtain other general information on your responsibilities under the Act from the Division of Industry and Consumer Education at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address

http://www.fda.gov/MedicalDevices/ResourcesforYou/Industry/default.htm.

Sincerely yours,

Ribhi Shawar -S
For

Uwe Scherf, M.Sc., Ph.D. Director Division of Microbiology Devices Office of In Vitro Diagnostics and Radiological Health Center for Devices and Radiological Health

Enclosure

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Indications for Use

Form Approved: OMB No. 0910-0120 Expiration Date: January 31, 2017 See PRA Statement below.

510(k) Number (if known)

Device Name

Liofilchem MIC Test Strip (MTS). Tedizolid 0.002-32 ug/mL

Indications for Use (Describe)

The Tedizolid MTS at concentrations of 0.002-32 ug/mL should be interpreted at 16-20 hours of incubation.

The non-fastidious bacteria that have been shown to be active both clinically and in vitro against Tedizolid according to the FDA label are:

Staphylococcus aureus (including methicillin-resistant and methicillin susceptible isolates) Enterococcus faecalis

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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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).