VTEC-RPLA "SEIKEN" is an in vitro diagnostic device for the detection and identification of verotoxic device for in culture isolates of E. coli and is intended as an aid in the diagnosis of Enterohemorrhagic E. coli (EHEC) infections.

Device Description

VTEC-RPLA "SEIKEN" is a reagent system which can be used for the detection of verotoxins in culture isolates of E. coli to aid in the diagnosis of EHEC infections. It employs antibody-antigen reactions as part of the assay and is based on reversed passive latex agglutination (RPLA). VTEC-RPLA utilizes polyclonal antibodies specific for each verotoxin type, VT1 and VT2, and thus may be used to identify toxins.

AI/ML Overview

This document describes the VTEC-RPLA "SEIKEN" device, an in vitro diagnostic procedure for detecting and identifying verotoxins in E. coli culture isolates to aid in diagnosing Enterohemorrhagic E. coli (EHEC) infections.

Here's an analysis of the acceptance criteria and the study that proves the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance

Acceptance Criteria	Target Performance (Implicit from Predicate Device)	Reported VTEC-RPLA "SEIKEN" Performance
Correlation	100% Sensitivity, 100% Specificity	100% Sensitivity, 100% Specificity
Sensitivity (VT1)	Min. Detectable Conc. ≤ 7 pg/well	25 pg/well
Sensitivity (VT2)	Min. Detectable Conc. ≤ 15 pg/well	25 pg/well
VTEC-RPLA Titers (VT1)	Consistent titers (e.g., within 1:64 to 1:128)	Consistent titers (1:64 to 1:128)
VTEC-RPLA Titers (VT2)	Consistent titers (e.g., within 1:64 to 1:128)	Consistent titers (1:64 to 1:128)
Specificity	No false positives with non-verotoxin-producing strains	No false positives
Reproducibility	Consistent results across operators, days, and lots	Consistent titers (1:64 to 1:128)
Dilution	Expected agglutination titers at dilutions	Agglutination titer at expected range
Stability	Performance maintained for at least 1 year at 2-10 °C	Performance maintained for 15 months (set to 1 year)

Note on Sensitivity: While the VTEC-RPLA "SEIKEN" has a higher minimum detectable concentration (25 pg/well for both VT1 and VT2) compared to the predicate device Premier EHEC (7 pg/well for VT1 and 15 pg/well for VT2), the correlation study still showed 100% sensitivity and specificity when directly comparing both devices with clinical isolates. The FDA's substantial equivalence determination implies that this difference in analytical sensitivity does not compromise clinical performance for the intended use.

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

Study 1 (in-house, Correlation):
- Sample Size: 100 Escherichia coli strains (80 verotoxin-producing, 20 non-verotoxin producing).
- Data Provenance: Obtained from the Japanese National Institute of Infectious Disease. Retrospective (as strains were obtained and then tested).
Study 2 (external, Correlation):
- Sample Size: 178 Escherichia coli strains (147 verotoxin-producing, 31 non-verotoxin producing) isolated from humans.
- Data Provenance: Tested by the Tokyo Metropolitan Research Laboratory of Public Health. Retrospective.
Sensitivity: 2 verotoxin-producing strains (DK-EC-VT1 and DK-EC-VT2).
Specificity: 8 verotoxin-producing and 12 non-producing strains of E. coli.
Reproducibility: Same 2 verotoxin-producing strains as Sensitivity study.
Dilution: 3 verotoxin-producing strains (DK-EC-PS 1 (VT1), DK-EC- PS 4 (VT2), and DK-EC-PS 7 (VT1 and VT2)).
Stability: Same 3 reagent lots as Sensitivity study, tested over time.

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

The document does not specify the number or qualifications of experts used to establish the ground truth for the test set.

However, for the external correlation study (Study 2), the ground truth for the 178 E. coli strains was established by parallel testing using:

VTEC-RPLA "SEIKEN"
PCR (Polymerase Chain Reaction)
Vero cell assay

The Vero cell assay is a widely accepted method for detecting verotoxicity. PCR is also a molecular method often considered a gold standard for pathogen detection and characterization. The document implies these methods collectively served as the reference for determining whether a strain was "verotoxin-producing" or "non-verotoxin producing."

4. Adjudication Method for the Test Set

The document does not explicitly describe an adjudication method for conflicting results if they occurred. However, given that both correlation studies reported 100% sensitivity and 100% specificity for VTEC-RPLA "SEIKEN" compared to the predicate (Study 1) and compared to PCR and Vero cell assay (Study 2), it suggests there were no conflicting results or that discrepancies were resolved in a manner not detailed here. The ground truth seems to be established by the consensus of the reference methods (for Study 2) or the predicate device (for Study 1).

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

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not performed. This device is an in-vitro diagnostic (IVD) reagent system, not an imaging device or algorithm requiring human interpretation. Therefore, the concept of "human readers improving with AI vs. without AI assistance" is not applicable here.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

Yes, the studies conducted are essentially standalone performance evaluations of the VTEC-RPLA "SEIKEN" device. It is a laboratory-based assay where the "performance" is the device's ability to detect and identify verotoxins. There is no "human-in-the-loop" component in the sense of an algorithm providing assistance for human interpretation; the device generates a result directly.

7. The Type of Ground Truth Used

Study 1 (Correlation): The ground truth for the 100 E. coli strains was established by comparison with the Premier EHEC Reagent System, a legally marketed predicate device.
Study 2 (Correlation): The ground truth for the 178 E. coli strains was established using a combination of PCR and the Vero cell assay. The Vero cell assay can be considered a form of biological activity assay or functional assay, which approximates outcomes data in terms of cellular toxicity, and PCR provides definitive genetic identification of toxin genes.
Sensitivity, Specificity, Reproducibility, Dilution: The ground truth involved using known verotoxin-producing and non-producing strains, and purified verotoxin preparations with defined concentrations. This is based on established expert classification through prior characterization of these strains and preparations.

8. The Sample Size for the Training Set

The document does not mention a "training set" in the context of machine learning or AI development. This is an in-vitro diagnostic test, not an AI/ML-based device. The studies described are validation and verification studies for its performance.

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

Since there is no "training set" for an AI/ML model, this question is not applicable. The document describes how the reference materials (strains, purified toxins) used in the verification studies were characterized, as outlined in point 7.

Summary

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SEP 2 2 1998

. ... ..

K981734

ATTACHMENT B

SUMMARY OF SAFETY AND EFFECTIVENESS

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SUMMARY OF SAFETY AND EFFECTIVENESS

VTEC-RPLA "SEIKEN"

Below summarizes and compares the performance of VTEC-RPLA "SEIKEN" and a similar device previously given FDA clearance for marketing in the US. The information contained in this summary was obtained from data prepared at and which is on file at Denka Seiken Co., Inc. This summary shows that the two reagent systems are substantially equivalent.

INTENDED USE

This in vitro diagnostic procedure is intended for the detection and identification of verotoxins or shiga-like toxins in culture isolates of E. coli. Such characterization is useful in the diagnosis of Enterohemorrhagic E. coli (EHEC) infections.

METHOD	VTEC-RPLA "SEIKEN"	Premier EHEC
Product code	230553	608096
Min. Detectable Conc.
VT 1	25 pg/well	7 pg/well
VT2	25 pg/well	15 pg/well

Correlation

Specificity and sensitivity between the two tests were 100% and 100%, respectively.

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VTEC-RPLA "SEIKEN" and Premier EHEC are similar in that both:

- Are reagent systems which can be used for the detection of verotoxins in culture isolates of E. coli to aid in the diagnosis of EHEC infections.
- Employ antibody-antigen reactions as part of the assay.

VTEC-RPLA "SEIKEN" and Premier EHEC are different in that:

- They use different culture conditions to prepare specimens
- VTEC-RPLA is based on reversed passive latex agglutination (RPLA) while the Premier EHEC is an enzyme immuno assay (EIA).
- The minimal detectable concentration for the VTEC-RPLA is approximately 25 pg / well ; that for the Premier EHEC is 7- 15 pg / well.
- VTEC-RPLA utilizes polyclonal antibodies specific for each verotoxin type, VT1 and VT2, and thus may be used to identify toxins; the Premier EHEC uses three types of antibody: an anti-VT monoclonal (EIA capture); anti-VT polyclonal (enzyme conjugate); and anti-rabbit IgG goat IgG conjugated with POD; the assay is specific for verotoxins but not type specific, ie cannot identify VT1 and VT2.
- Premier EHEC may be used to directly detect verotoxins in stools, in mixed cultures and in culture isolates while VTEC-RPLA is intended for use with culture isolates only.

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PROTOCOL AND DATA SUMMARY

This section provides data generated by and for Denka Seiken Co., Ltd. characterizing the performance of VTEC-RPLA "SEIKEN". The protocols used for the data generation are given below, and the results are attached.

CORRELATION

Study 1 (in-house)

One hundred Eschericia coli strains (80 verotoxin-producing and 20 non-verotoxin producing) were obtained from the Japanese National Institute of Infectious Disease and tested in parallel using VTEC-RPLA "SEIKEN" and the Premier EHEC Reagent System. Specimens were prepared and tested according to the product inserts given in the kits. 100% sensitivity and 100% specificity were observed. Study 2 (external)

One hundred and seventy eight Eschericia coli strains (147 verotoxin-producing and 31 non-verotoxin producing) isolated from humans were tested by the Tokyo Metropolitan Research Laboratory of Public Health using VTEC-RPLA "SEIKEN", PCR and the vero cell assay. 100% sensitivity and 100% specificity were observed.

SENSITIVITY

Three reagent lots (Lot No. 3421, No. 3626 and No. 31222) and two verotoxinproducing strains, DK-EC-VT1 and DK-EC-VT2, obtained from Kyoto University Faculty of Medicine, were used in these studies. Verotoxin type 1 and verotoxin type 2 were purified from the respective strains above and preparations were adjusted to 100 ng/ml for testing. Each verotoxin preparation was tested with each reagent lot three times and all three lots showed titers of between 1:64 to 1:128 in all replicates.

SPECIFICITY

Three reagent lots (Lot No. 3421, No. 3626 and No. 31222) , eight verotoxin-producing and twelve non-producing strains of E. coli were used in these studies. Specimens were prepared using the CA-YE shaking broth recommended in the product insert and the resulting culture supernatants from each strain were lyophilized and subsequently tested in triplicate after reconstitution. Positive results were obtained from verotoxin-producing strains and, likewise, negative results only from non-producing strains.

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REPRODUCIBILITY

Reagent lots and verotoxin specimens were the same as those described in SEN-SITIVITY above. Each verotoxin preparation was tested with each reagent lot five times and the resulting titers for all assays were between 1:64 to 1:128. Also, performed were Person--to--person: testing done by three operators Day--to--day: testing done on five different days Lot -- to -- lot: testing done with three different lots All of the above studies showed agglutination titers of between 1:64 to 1:128.

DILUTION

Three verotoxin-producing strains, DK-EC-PS 1 (VT1), DK-EC- PS 4 (VT2) and DK-EC-PS 7 (VT1 and VT2), were cultured in CA-YE by the broth culture method and the supernatants obtained after cell-pelleting, in addition to ten-fold dilutions in saline, were each tested in a single examination. All ten-fold dilutions showed an agglutination titer at the expected range.

STABILITY

To establish storage conditions and the reagent shelf-life, the above three reagent lots were tested at 0, 3, 6, 9, 12 and 15 months with regards to sensitivity, specificity and reproducibility as described above. Reagents were store at 12 C. As there was no change in reagent performance throughout this time, the storage conditions and shelf-life were set at 2-10 C and one year after production, respectively.

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Image /page/5/Picture/2 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo features a stylized eagle with its wings spread, and the words "DEPARTMENT OF HEALTH & HUMAN SERVICES USA" are arranged in a circular pattern around the eagle. The logo is black and white and appears to be a scanned image.

SEP 2 2 1998

Food and Drug Administration 2098 Gaither Road Rockville MD 20850

Kevin Mangan International Sales and Business Development Denka Seiken Co., Ltd. 3-4-2. Nihonbashi-Kavabacho Chuo-Ku Tokyo, Japan 103-0025

Re: K981734 Trade Name: VTEC-RPLA "SEIKEN" Regulatory Class: I Product Code: GNA Dated: August 14, 1998 Received: August 17, 1998

Dear Mr. Mangan:

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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Under the Clinical Laboratory Improvement Amendments of 1988 (CLIA-88), this device may require a CLIA complexity categorization. To determine if it does, you should contact the Centers for Disease Control and Prevention (CDC) at (770)488-7655.

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" (21 CFR 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 at (301) 443-6597 or at its internet address "http://www.fda.gov/cdrh/dsmamain.html"

Sincerely yours,

Steven Autman

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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Page -

510(k) Number (ii known) K981734

Device Name: VTEC-RPLA

Indications For Use

FDA/CDRH/ODE/DMC

12 JUN 93
1305

INITIALED

(PLEA
NEEDED

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

Concurrence of CDRH, Office of Device Evaluation (ODE)

Woody Dubois

n of Clinical Laboratory Devices Number

Prescription Use (Per 21 CFR 801.109)

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Gver-The-Counter Use__________________________________________________________________________________________________________________________________________________________

(Optional Format 1-2-96)

SK-23

Regulation Number and Section

§ 866.3255

Escherichia coli serological reagents.(a)
Identification. Escherichia coli serological reagents are devices that consist of antigens and antisera used in serological tests to identifyEscherichia coli from cultured isolates derived from clinical specimens. Additionally, some of these reagents consist ofEscherichia coli antisera conjugated with a fluorescent dye used to identifyEscherichia coli directly from clinical specimens or cultured isolates derived from clinical specimens. The identification aids in the diagnosis of diseases caused by this bacterium belonging to the genusEscherichia, and provides epidemiological information on diseases caused by this microorganism. AlthoughEscherichia coli constitutes the greater part of the microorganisms found in the intestinal tract in humans and is usually nonpathogenic, those strains which are pathogenic may cause urinary tract infections or epidemic diarrheal disease, especially in children.(b)
Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 866.9.