The DensiCHEK™ Plus instrument is intended for use with the VITEK® and VITEK® 2 Systems to measure the optical density of a microorganism suspension. The instrument provides values in McFarland units, proportional to microorganism concentrations. DensiCHEK Plus is indicated for use with polystyrene and glass test tubes and the reading range is 0.0 - 4.0 McFarland. The DensiChek™ Plus has applications as an in vitro diagnostic device.

Device Description

The DensiCHEK Plus generates a McFarland value using basic colorimetry, which is a method of measurement that relates the amount of color in a transparent medium (liquid) to the amount of a particular substance in the liquid. In general the concentration of the substance being measured is proportional to the intensity of the solution. The darker the color is, the higher the concentration. Absorbance (Abs) is a commonly used measure of the amount of light absorbed by the solution. Absorbance is given by: Abs = - log T or Abs = - log (Ir/10) Where: T = Transmittance Ir = Intensity of light transmitted through the sample 10 = Intensity of light entering the sample The DensiCHEK Plus measures the turbidity of the saline and microorganism suspension using a single wavelength, 580 nm. The absorption of light determines the McFarland value generated by the instrument. The more turbid the suspension is, the higher the McFarland standard measurement. The light source in the DensiCHEK plus is an LED that emits a narrow range of wavelengths, and an interference filter is used between the LED and the test tube (sample) to further narrow the wavelength to 580 nm. There are 2 calibration curves pre-programmed into the DensiCHEK Plus, one for glass tubes and one for plastic tubes. The absorbance is different for glass and plastic, therefore the laboratory technician using the DensiCHEK Plus must choose the appropriate tube type setting for the inoculum suspension based on whether it was prepared in a glass or plastic test tube: The instrument is first zeroed using a test tube filled with saline (blank). The technician then places the well-mixed organism suspension into the instrument and slowly rotates the test tube. The instrument will display a series of dashes followed by a McFarland reading.

AI/ML Overview

The provided document K093224 describes a Special 510(k) Device Modification for the DensiCHEK™ Plus to add VITEK® 2 AST-YS to the list of products for which it can be used. It emphasizes that the device design and fundamental scientific technology were not altered. The submission confirms that the modified device demonstrated substantially equivalent performance to the unmodified device (K083536) during risk assessment studies.

However, the provided text does not contain explicit acceptance criteria or a detailed study report with specific performance metrics and statistical analyses to prove the device meets these criteria. The approval is based on "substantially equivalent performance during risk assessment studies," rather than a detailed performance study with defined criteria.

Given the absence of this information in the provided document, I cannot complete several sections of your request.

Here's a breakdown of what can and cannot be answered based solely on the provided text:

1. A table of acceptance criteria and the reported device performance

Acceptance Criteria	Reported Device Performance
Not Explicitly Stated in Document	The DensiCHEK Plus modified device "demonstrated substantially equivalent performance during risk assessment studies when compared with the DensiCHEK Plus unmodified device." Performance with VITEK 2 AST-YS and DensiCHEK Plus "has now been established."

Explanation: The document states that the modified device demonstrated "substantially equivalent performance" to the predicate device. However, it does not provide specific numerical acceptance criteria (e.g., accuracy, precision ranges) or detailed performance data against such criteria.

2. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)

Not available in the document. The text mentions "risk assessment studies" but does not detail the sample size, type of test sets used, or data provenance.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)

Not applicable/available in the document. This device measures optical density (McFarland units) and does not rely on expert interpretation for ground truth establishment. The ground truth for such a device would typically be established by highly calibrated reference instruments or gravimetric methods. This information is not provided.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set

Not applicable/available in the document. As stated above, this device measures optical density directly, and its performance would be assessed against a known reference, not through an adjudication process involving human experts.

5. 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 an automated optical density measurement instrument, not an AI-assisted diagnostic tool that involves human readers.

6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done

Yes, implicitly. The DensiCHEK Plus is a standalone instrument that measures turbidity and generates a McFarland value. Its performance evaluation would inherently be standalone, comparing its output to a reference standard. The document states it "demonstrated substantially equivalent performance" which implies standalone performance was evaluated.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc)

Not explicitly stated in the document. For an optical density measurement device, the ground truth would typically be established by a primary reference method for turbidity/concentration, such as gravimetric analysis or highly calibrated spectrophotometers/densitometers.

8. The sample size for the training set

The document describes a device modification, not the development of a new algorithm that would typically have a "training set" in the context of machine learning. The DensiCHEK Plus uses basic colorimetry and pre-programmed calibration curves. Therefore, this concept of a "training set" in the context of data-driven algorithm development is not applicable here. The calibration curves are likely established during manufacturing and validation, not through a "training set" in the AI sense.

9. How the ground truth for the training set was established

As explained above, the concept of a "training set" for an algorithm like an AI model is not applicable to this device's description. The device uses pre-programmed calibration curves established from physical measurements and references, not a machine learning training process with corresponding ground truth data.

Summary

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K093224

BIOMÉ R ! E U X

510(k) SUMMARY

DensiCHEK™ Plus Special 510(k): Device Modification

NOV - 9 2009

510(k) Submission Information:

Submitter's Name: Address:

Contact Person:

Phone Number:

Fax Number:

Date of Preparation:

B. Device Name:

Formal/Trade Name:

Classification Name:

October 13, 2009

bioMérieux, Inc.

John Tenllado

314 -731-8386

314-731-8689

595 Anglum Road Hazelwood, MO 63042

Senior Manager, Regulatory Affairs

DensiCHEK™ Plus

DensiCHEK Plus

Fully Automated Short-Term Incubation Cycle Antimicrobial Susceptibility Device, 21 CFR 866.1645

Common Name:

C. Predicate Device:

DensiCHEK Plus (K083536)

D. 510(k) Summary:

DensiCHEK100 Plus is intended for use with the VITEK® and VITEK® 2 Systems to measure the optical density of a microorganism suspension. The instrument provides values in McFarland units, proportional to microorganism concentrations. DensiCHEK Plus is indicated for use with polystyrene and glass test tubes and the reading range is 0.0 - 4.0 McFarland. The DensiCHEK Plus has applications as an in vitro diagnostic medical device.

The intended use of the DensiCHEK Plus, as described in its labeling (DensiCHEK Plus Instrument User Manual), has not changed as a result of this modification to add VITEK 2 AST-YS to the list of products appropriate for use with DensiCHEK Plus now that performance has been established. This modification does not affect the fundamental scientific technology of this device. The device design was not altered in any way.

Abs = - log T or Abs = - log (1-/10)

bioMérieux, Inc.

595 Anglum Road, Hazelwood, Missouri 63042-2320, USA Phone: 314/731-8500 800/638-4835 Fax: 314/731-8700

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Where:

T = Transmittance

Ir = Intensity of light transmitted through the sample

10 = Intensity of light entering the sample

The DensiCHEK Plus measures the turbidity of the saline and microorganism suspension using a single wavelength, 580 nm. The absorption of light determines the McFarland value generated by the instrument. The more turbid the suspension is, the higher the McFarland standard measurement. The light source in the DensiCHEK plus is an LED that emits a narrow range of wavelengths, and an interference filter is used between the LED and the test tube (sample) to further narrow the wavelength to 580 nm. There are 2 calibration curves pre-programmed into the DensiCHEK Plus, one for glass tubes and one for plastic tubes. The absorbance is different for glass and plastic, therefore the laboratory technician using the DensiCHEK Plus must choose the appropriate tube type setting for the inoculum suspension based on whether it was prepared in a glass or plastic test tube: The instrument is first zeroed using a test tube filled with saline (blank). The technician then places the well-mixed organism suspension into the instrument and slowly rotates the test tube. The instrument will display a series of dashes followed by a McFarland reading.

The DensiCHEK Plus modified device, to include VITEK 2 AST-YS as a product applicable for use with this device, demonstrated substantially equivalent performance during risk assessment studies when compared with the DensiCHEK Plus unmodified device cleared under K083536. Performance with VITEK 2 AST-YS and DensiCHEK Plus has now been established. This Special 510(k) Device Modification presents data in support of DensiCHEK Plus labeling change to add VITEK 2 AST-YS to the list of applicable products for which it can be used to aid in microorganism suspension prepration.

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Image /page/2/Picture/0 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo consists of a stylized eagle with three stripes representing the department's mission. The text "DEPARTMENT OF HEALTH & HUMAN SERVICES (USA)" is arranged in a circular pattern around the eagle.

DEPARTMENT OF HEALTH & HUMAN SERVICES

Public Health Service

Food and Drug Administration 10903 New Hampshire Avenue Building 66 Silver Spring, MD 20993

Jolyn Tenllado Senior Manager, Regulatory Affairs bioMerieux, Inc. 595 Anglum Road . Hazelwood, MO 63042

Re: K093224

Trade/Device Name: DensiCHEKTM Plus Regulation Number: 21 CFR 866.1645 Regulation Name: Fully automated short-term incubation cycle antimicrobial susceptibility device Regulatory Class: Class II Product Code: LON

9 2009

NOV

Dated: October 13, 2009 Received: October 14, 2009

Dear Ms. Tenllado:

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.

If your device is classified (see above) into class II (Special Controls), it may be subject to such additional controls. Existing major regulations affecting your device can be found in Title 21, Code of Federal Regulations (CFR), Parts 800 to 895. In addition, FDA may publish further announcements concerning your device in the Federal Register.

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Page 2 - Ms. Tenllado

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 of medical device-related adverse events) (21 CFR 803); and good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820). This letter will allow you to begin marketing your device as described in your Section 510(k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.

If you desire specific advice for your device on our labeling regulation (21 CFR Parts 801 and 809), please contact the Office of In Vitro Diagnostic Device Evaluation and Safety at (301) 796-5450. 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 Small Manufacturers, International and Consumer Assistance at its toll-free number (800) 638-2041 or (301) 796-5680 or at its Internet address http://www.fda.gov/cdrh/industry/support/index.html.

Sincerely yours,

Sazastopns

Sally A. Hojvat, Ph.D. Director, Division of Microbiology Devices Office of In Vitro Diagnostic Device Evaluation and Safety Center for Devices and Radiological Health

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Indications for Use

510(k) Number (if known):_ 1093 and

Device Name: DensiCHEK™ Plus

Indications For Use:

Prescription Use (Part 21 CFR 801 Subpart D)

AND/OR

Over-The-Counter Use (21 CFR 807 Subpart C)

(PLEASE DO NOT WRITE BELOW THIS LINE-CONTINUE ON ANOTHER PAGE IF NEEDED)

Concurrence of CDRH, Office of In Vitro Diagnostic Devices (OIVD)

Freddie th. Poole

Division Sign-Off

Page 1 of 1

Office of In Vitro Diagnostic Device Evaluation and Safety

510(k) K093224

p. 36

Regulation Number and Section

§ 866.1645 Fully automated short-term incubation cycle antimicrobial susceptibility system.

(a)
Identification. A fully automated short-term incubation cycle antimicrobial susceptibility system is a device that incorporates concentrations of antimicrobial agents into a system for the purpose of determining in vitro susceptibility of bacterial pathogens isolated from clinical specimens. Test results obtained from short-term (less than 16 hours) incubation are used to determine the antimicrobial agent of choice to treat bacterial diseases.(b)
Classification. Class II (special controls). The special control for this device is FDA's guidance document entitled “Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA.”