The VIDAS® TOXO IgG II (TXG) assay is intended for use with a VIDAS® (Vitek ImmunoDiagnostic Assay System) instrument as a quantitative automated enzyme-linked fluorescent immunoassay (ELFA) for the measurement of Toxoplasma gondii-specific IgG in human serum or plasma (EDTA, heparin). It is intended for use as an aid in determination of immune status. It is not intended for use in testing (screening) blood or plasma donors.

Device Description

The VIDAS TOXO IgG II (TXG) assay is an automated quantitative test that is performed in a VIDAS instrument. All assay steps and assay temperature are controlled by the VIDAS instrument. The assay principle combines a two step enzyme immunoassay sandwich method with a final fluorescent detection (ELFA). The Solid Phase Receptacle (SPR) serves as the solid phase as well as the pipetting device for the assay. Reagents for the assay are ready-to-use and pre-dispensed in the sealed reagent strips. All of the assay steps are performed automatically by the instrument. The VIDAS TXG kit contains 60 TXG Reagent Strips, 60 TXG SPRs, 1 bottle of calibrator, and 1 bottle each of Positive and Negative controls. Each VIDAS TXG assay requires one TXG Reagent Strip and one TXG SPR.

AI/ML Overview

Here's a breakdown of the acceptance criteria and study details for the VIDAS TOXO IgG II (TXG) assay based on the provided text:

Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly stated as numerical targets in a formal "acceptance criteria" table. Instead, the study aims to demonstrate "substantial equivalence" to the predicate device. The performance metrics presented are relative sensitivity and relative specificity.

Performance Metric	Acceptance Criteria (Implied for Substantial Equivalence)	Reported Device Performance
Relative Sensitivity	High (e.g., above a certain threshold, implicitly compared to predicate)	98.45% (95% CI: 97.06%-99.29%)
Relative Specificity	High (e.g., above a certain threshold, implicitly compared to predicate)	99.77% (95% CI: 99.33%-99.95%)

Note: The FDA's 510(k) clearance process focuses on substantial equivalence to a legally marketed predicate device, rather than strictly defined numerical acceptance criteria like those sometimes seen for novel devices. The high sensitivity and specificity relative to the predicate were deemed sufficient to demonstrate substantial equivalence.

Study Details

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

Sample Size: 1940 serum samples.
Data Provenance: Not explicitly stated (e.g., country of origin). The study is retrospective in nature as it tests existing serum samples with both the new device and the predicate device.

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

Number of Experts: Not applicable. The "ground truth" for the clinical testing was established by the predicate device (Abbott IMx Toxo IgG 2.0 Antibody Assay) acting as the reference comparator.

4. Adjudication Method for the Test Set

Adjudication Method: For initial VIDAS equivocal samples, retesting was performed as directed in the package insert. The text mentions "there were 30 VIDAS equivocal results and 19 Abbott equivocal results" from the original 1940 samples. It doesn't specify further adjudication beyond the retesting of VIDAS equivocal samples. No inter-reader or expert consensus adjudication is mentioned, as the predicate device served as the primary comparison.

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

No, an MRMC comparative effectiveness study was not performed. This study is for an in-vitro diagnostic (IVD) assay, which involves automated or semi-automated detection, not human reader interpretation of images or data that would typically necessitate an MRMC study.

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

Yes, the study describes the standalone performance of the VIDAS TOXO IgG II (TXG) assay. It is an "automated quantitative test" and an "automated enzyme-linked fluorescent immunoassay (ELFA)." The sensitivity and specificity reported are for the device itself against the predicate.

7. The Type of Ground Truth Used

Type of Ground Truth: The ground truth was based on the performance of a predicate device – the Abbott IMx Toxo IgG 2.0 Antibody Assay. This means the study established the relative performance of the new device compared to an already legally marketed and accepted device.

8. The Sample Size for the Training Set

Training Set Sample Size: Not explicitly stated. The document focuses on the performance of the final, developed assay. IVD assays like this typically undergo extensive development and internal validation, but the "training set" in the context of machine learning (which this device is not) doesn't directly apply here. The document details nonclinical testing (cross-reactivity, precision, linearity) which typically informs assay development and refinement.

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

Ground Truth for Training Set: Not applicable in the machine learning sense. For an IVD assay, the equivalent of "ground truth" for development would involve well-characterized reference materials, known positive and negative samples, and samples with various concentrations to establish assay parameters, linearity, and precision. The nonclinical testing section describes some of these processes:
- Cross-reactivity/Interference: 85 samples from patients with various disease states and known anti-T. gondii IgG status were used. This "known status" would be established through other validated methods.
- Linearity: Dilutions of 4 serum samples and the WHO standard were tested. The WHO standard is an internationally recognized reference material that provides a "ground truth" for specific concentrations.

Summary

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K993319

510(k) SUMMARY

This summary of 510(k) safety and effectiveness information is being submitted in accordance with the requirements of SMDA 1990 and 21 CFR 807.92.

510(k) Number:

Submitter:	bioMerieux, Inc.1022 Hingham StreetRockland, MA 02370Phone (781) 871-4442Fax (781) 871-3470Contact Name: Anna J. DeMarinis
Date:	September 30, 1999
Device Trade/Proprietary Name:	VIDAS TOXO IgG II (TXG) assay
Common or Usual Name:	Enzyme-linked Fluorescent Immunoassay (ELFA)for the quantitative determination of Toxoplasmagondii- specific IgG
Classification Name:	21 CFR 866.3780, Toxoplasma gondii serologicalreagents
Predicate Device:	Abbott IMx Toxo IgG 2.0 Antibody Assay

Device Description:

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Intended Use:

VIDAS® TOXO IgG II (TXG) is an automated quantitative test for use on a VIDAS® analyser for the quantitative measurement of anti- Toxoplasma gondii IgG in human serum or plasma (EDTA, heparin). It is intended for use as an aid in determination of immune status. It is not intended for use in testing (screening) blood or plasma donors.

Summary/Comparison of Technological Characteristics

The VIDAS TXG assay is substantially equivalent to the Abbott IMx Toxo IgG 2.0 Antibody Assay.

Maior similarities include:

1. Both are enzyme immunoassays which detect IgG antibodies to Toxoplasma gondii in human serum or plasma.
1. Both utilize 4-methylumbelliferyl phosphate substrate.

Major differences include:

1. The VIDAS TXG assay uses a Solid Phase Receptacle (SPR) to capture anti-T. gondii IgG. The IMx uses microparticles for capture.
1. The VIDAS TXG assay is a fully automated enzyme-linked fluorescent immunoassay (ELFA) which uses sealed reagent strips containing all reagents necessary for the assay. The IMx requires separate addition of reagents to the system.
1. The VIDAS TXG assay provides a factory created master curve which only requires running a single calibrator. The IMx requires running a set of calibrators.

Synopsis of Performance Testing

Nonclinical Testing:

1. Cross-reactivity/Interference: In two separate studies, a total of 85 samples from patients with a variety of disease states (and known anti-T. gondii IgG status) were tested in the VIDAS TXG assay. None of the samples tested yielded unexpected results.
1. Precision: Within-run precision calculations as described by NCCLS EP5-T2 yielded % CV ranging from 5.13 % to 7.21 % over the reportable range of the assay. Total precision calculations as described by NCCLS EPS-T2 yielded % CV ranging from 6.70 % to 11.52 % over the reportable range of the assay.
1. Linearity: Dilutions of 4 serum samples and the WHO standard were tested using the VIDAS TXG assay. Linear regression analysis of the results vielded correlation coefficients of 0.98 or greater.

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Clinical Testing:

1. Sensitivity and Specificity (relative to predicate device): One thousand nine hundred forty serum samples were tested using the VIDAS TXG assay and the Abbott IMx Toxo IgG Antibody Assay. After retesting of initial VIDAS equivocal samples (as directed in the package insert), there were 30 VIDAS equivocal results and 19 Abbott equivocal results. For the remaining 1891 samples, the VIDAS TXG assay showed a relative sensitivity of 98.45% (95% confidence interval 97.06%-99.29%) and a relative specificity of 99.77% (95% confidence interval 99.33%-99.95%).
  These results support a determination of substantial equivalence. When the VIDAS TXG assay is used as instructed in the package insert, the above statements are true. The package insert should always be consulted along with a VIDAS Procedures Manual to ensure that the assay is being performed properly. For additional information, references are listed in the package insert.

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MAY 2 2 2000

Food and Drug Administration 2098 Gaither Road Rockville MD 20850

Ms. Sandra L. Perreand Manager, Regulatory Affairs BioMérieux, Inc. 595 Anglum Drive Hazelwood, Missouri 63042

Re: K993319

Trade Name: VIDAS® TOXO IgG II (TXG) Assay Regulatory Class: II Product Code: LGD Dated: May 4, 2000 Received: May 11, 2000

Dear Ms. Perreand:

We have reviewed your Section 510(k) notification of intent to market the device referenced above and we 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). 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 either class II (Special Controls) or class III (Premarket Approval), it may be subject to such additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 895. A substantially equivalent determination assumes compliance with the Current Good Manufacturing Practice requirements, as set forth in the Quality System Regulation (QS) for Medical Devices: General regulation (21 CFR Part 820) and that, through periodic QS inspections, the Food and Drug Administration (FDA) will verify such assumptions. Failure to comply with the GMP regulation may result in regulatory action. In addition, FDA may publish further announcements concerning your device in the Federal Register. Please note: this response to your premarket notification submission does not affect any obligation you might have under sections 531 through 542 of the Act for devices under the Electronic Product Radiation Control provisions, or other Federal laws or regulations.

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This letter will allow you to begin marketing your device as described in your 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 Part 801 and additionally 809.10 for in vitro diagnostic devices), please contact the Office of Compliance at (301) 594-4588. Additionally, for questions on the promotion and advertising of your device. please contact the Office of Compliance at (301) 594-4639. Also, please note the regulation entitled. "Misbranding by reference to premarket notification" (21CFR 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers Assistance at its toll-free number (800) 638-2041 or (301) 443-6597 or at its internet address "http://www.fda.gov/cdrh/dsma/dsmamain.html".

Sincerely yours,

Steven Butman

Steven I. Gutman, M.D., M.B.A. Director Division of Clinical Laboratory Devices Office of Device Evaluation Center for Devices and Radiological Health

Enclosure

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510(k) Number (if known):

Device Name: VIDAS TOXO IgG II (TXG) Assay

Indications for Use:

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

Concurrence of CDRH, Office of Device Evaluation (ODE)

Woody Dubois

510(k) Number

Prescription Use_y____________________________________________________________________________________________________________________________________________________________

Over-the-Counter Use _________________________________________________________________________________________________________________________________________________________

Regulation Number and Section

§ 866.3780

Toxoplasma gondii serological reagents.(a)
Identification. Toxoplasma gondii serological reagents are devices that consist of antigens and antisera used in serological tests to identify antibodies toToxoplasma gondii in serum. Additionally, some of these reagents consist of antisera conjugated with a fluorescent dye (immunofluorescent reagents) used to identifyToxoplasma gondii from clinical specimens. The identification aids in the diagnosis of toxoplasmosis caused by the parasitic protozoanToxoplasma gondii and provides epidemiological information on this disease. Congenital toxoplasmosis is characterized by lesions of the central nervous system, which if undetected and untreated may lead to brain defects, blindness, and death of an unborn fetus. The disease is characterized in children by inflammation of the brain and spinal cord.(b)
Classification. Class II (performance standards).