K Number
K063866
Date Cleared
2007-03-19

(80 days)

Product Code
Regulation Number
866.3830
Reference & Predicate Devices
N/A
Predicate For
AI/MLSaMDIVD (In Vitro Diagnostic)TherapeuticDiagnosticis PCCP AuthorizedThirdpartyExpeditedreview
Intended Use

The Bio-Rad Syphilis IgG kit is a multiplex flow immunoassay intended for the qualitative detection of Treponema pallidum IgG antibodies in human serum. The test system, when used in conjunction with non-treponemal based assays, provides serological evidence of infection with T. pallidum. This test system is also indicated for use in confirming reactive test results from non-treponemal based screening assays.

The Syphilis IgG kit is intended for use with the Bio-Rad BioPlex 2200 System.

The BioPlex 2200 Syphilis IgG kit is not intended for use in screening blood or plasma donors.

Warning: A positive result is not useful for establishing a diagnosis of Syphilis. In most situations, such a result may reflect prior treated infection; a negative result can exclude a diagnosis of syphilis except for incubating or early primary disease.

Device Description

The Syphilis IgG kit uses multiplex flow immunoassay, a methodology that greatly resembles traditional EIA, but permits simultaneous detection and identification of many antibodies in a single tube. Three (3) different populations of dyed beads are coated with recombinant proteins associated with T. pallidum (15kD, 17kD and 47kD). The BioPlex 2200 System combines an aliquot of patient sample, sample diluent, and bead reagent into a reaction vessel. The mixture is incubated at 37°C. After a wash cycle, anti-human IgG antibody, conjugated to phycoerythrin (PE), is added to the dyed beads, and this mixture is incubated at 37°C. The excess conjugate is removed in another wash cycle, and the beads are re-suspended in wash buffer. The bead mixture then passes through the detector. The identity of the dyed beads is determined by the fluorescence of the dyes, and the amount of antibody captured by the antigen is determined by the fluorescence of the attached PE. Raw data is calculated in relative fluorescence intensity (RFI).

Three additional dyed beads, Internal Standard Bead (ISB), Serum Verification Bead (SVB) and a Reagent Blank Bead (RBB) are present in each reaction mixture to verify detector response, the addition of serum or plasma to the reaction vessel and the absence of significant non-specific binding in serum or plasma. Refer to the BioPlex 2200 System Operation Manual for more information.

The system is calibrated using a set of four (4) distinct calibrators vials, supplied separately by Bio-Rad Laboratories. Four (4) vials representing two (2) or three (3) different antibody concentrations are used for calibration. Results are calculated for each of the three (3) antibodies and are compared against their own respective cut-off and are expressed as an antibody index (AI). A single result is reported after completing a composite analysis of all the antibodies (the highest Al value is reported).

AI/ML Overview

Here's a breakdown of the acceptance criteria and study details for the BioPlex 2200 Syphilis IgG device, based on the provided text:

Acceptance Criteria and Device Performance

The acceptance criteria for the BioPlex 2200 Syphilis IgG device appear to be primarily focused on its agreement with established reference assays (RPR and TPPA, with treponemal EIA for discordant results) and its performance in various clinical populations. Specific quantitative acceptance criteria are not explicitly stated as distinct thresholds in the document, but rather are demonstrated through the reported percentages in the comparative testing tables.

Here’s a table summarizing the reported device performance in relation to the implied acceptance of sufficient agreement and sensitivity:

Acceptance Criteria / Performance CategorySpecific Metric (as reported)Reported Device Performance (%)95% Confidence Interval (where available)
Comparative Testing (Syphilis Test Ordered)
Positive Agreement (vs. Reference Assays)Serum Samples From Patients Who Had a Syphilis Test Ordered (N=500), Positive Reference Assays Result100% (46/46)92.0 - 100%
Negative Agreement (vs. Reference Assays)Serum Samples From Patients Who Had a Syphilis Test Ordered (N=500), Negative Reference Assays Result93.8% (426/454)91.2 - 95.7%
Comparative Testing (Unselected Pregnant Women)
Positive Agreement (vs. Reference Assays)Unselected Serum Samples From Pregnant Women (N=497), Positive Reference Assays Result100% (5/5)56.5 - 100%
Negative Agreement (vs. Reference Assays)Unselected Serum Samples From Pregnant Women (N=497), Negative Reference Assays Result99.8% (491/492)98.9 - 100%
Comparative Testing (RPR/TPPA Reactive Samples)
Positive Agreement (vs. Reference Assays)Serum Samples Requested to be RPR and TPPA Reactive (N=250), Positive Reference Assays Result100% (249/249)98.5 - 100%
Comparative Testing (Pregnant Women - Treponemal Assay Positive)
Positive Agreement (vs. Reference Assays)Serum Samples From Pregnant Women Requested to be Treponemal Assay Positive (N=183), Positive Reference Assays Result100% (166/166)97.7-100%
Comparative Testing (Pregnant Women - RPR/TPPA Nonreactive)
Negative Agreement (vs. Reference Assays)Serum Samples From Pregnant Women Requested to be RPR/TPPA Nonreactive (N=250), Negative Reference Assays Result98.8% (247/250)96.5 - 99.6%
Comparative Testing (Medically Diagnosed Syphilis)
Positive Agreement (vs. Reference Assays)Serum Samples From Patients Medically Diagnosed With Syphilis (N=70), Positive Reference Assays Result100.0% (63/63)94.2 - 100%
Clinical Sensitivity (Combined CDC Panel + Prospectively Collected Samples)
Overall Clinical SensitivityBioPlex 2200 Syphilis IgG vs. Combined CDC Panel and Prospectively Collected Samples With Known Clinical Status (N=150), Total Reactive92.0% (138/150)86.5 - 95.4%
Overall Reference Assay Clinical SensitivityBioPlex 2200 Syphilis IgG vs. Combined CDC Panel and Prospectively Collected Samples With Known Clinical Status (N=150), Total Reactive by Reference Assay89.5% (137/150)86.5 - 94.9%
Overall Positive Agreement (by Known Clinical Status)BioPlex 2200 Syphilis IgG vs. Reference Assays: Combined Percent Agreement By Known Clinical Status (N=150), Total100% (137/137)97.3 - 100%

The studies provided demonstrate a high degree of concordance and sensitivity of the BioPlex 2200 Syphilis IgG assay with established methods and known clinical status, supporting its intended use. Reproducibility and precision data also indicate reliable performance.


Study Details

Here's the detailed information about the studies:

2. Sample sizes used for the test set and the data provenance:

The document describes several test sets used for comparative testing, reproducibility, precision, cross-reactivity, and clinical sensitivity.

  • Comparative Testing (Primary Evaluation):
    • Serum Samples From Patients Who Had a Syphilis Test Ordered: N=500, sourced from three (3) U.S. clinical testing sites. (Provenence: U.S., likely retrospective, as they are "banked serum samples").
    • Unselected Serum Samples From Pregnant Women: N=497, sourced from three (3) U.S. clinical testing sites. (Provenance: U.S., likely retrospective, as they are "banked serum samples").
    • Serum Samples Requested to be RPR and TPPA Reactive: N=250, sourced from three (3) U.S. clinical testing sites. (Provenance: U.S., likely retrospective, as they are "banked purchased samples").
    • Serum Samples From Pregnant Women Requested to be Treponemal Assay Positive: N=183, sourced from three (3) U.S. clinical testing sites. (Provenance: U.S., likely retrospective, as they are "banked purchased samples").
    • Serum Samples From Pregnant Women Requested to be RPR/TPPA Nonreactive: N=250, sourced from three (3) U.S. clinical testing sites. (Provenance: U.S., likely retrospective, as they are "banked purchased samples").
    • Serum Samples From Patients Medically Diagnosed With Syphilis: N=70, sourced from three (3) U.S. clinical testing sites. (Provenance: U.S., "banked prospectively collected samples").
  • Reproducibility Studies: Seven (7) panel members per recombinant protein (15kD, 17kD, 47kD) were prepared by Bio-Rad Laboratories. Each member was tested in duplicate (x2) on 2 runs per day for 3 days at 3 U.S. testing facilities, resulting in 36 replicates per panel member. (Provenance: U.S., prospective testing of prepared panels).
  • Precision Studies: Nine (9) panel members per recombinant protein (15kD, 17kD, 47kD) were prepared by Bio-Rad Laboratories. Each member was tested in duplicate (x2) on 2 runs per day for 20 days, resulting in 80 replicates per panel member. (Provenance: Bio-Rad Laboratories, prospective testing of prepared panels).
  • Correlation with Known HIV-1 Positive Samples: N=220, banked known HIV-1 positive serum samples. (Provenance: Not explicitly stated, but implies retrospective collection).
  • Correlation with Disease Stages and Clinical Sensitivity (CDC Panel): N=140, CDC panel of banked frozen characterized sera. (Provenance: CDC, likely retrospective).
  • Correlation with Disease Stages and Clinical Sensitivity (Prospectively Collected): N=10, banked prospectively collected serum samples from treated and untreated patients with primary and secondary syphilis infections. (Provenance: One clinical testing site, prospective collection specified).
  • Cross-Reactivity: Ten (10) specimens positive for each cross-reactant (except E. Coli, N=4, and Lyme IgG Afzelli / Garnii, N=49). (Provenance: Not explicitly stated, likely sourced from various collections).

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

The document does not specify the number of experts or their qualifications for establishing the ground truth. It refers to "Reference Assays Result" (RPR, TPPA, and treponemal EIA for discordant results) and "Known Clinical Status" (for the CDC panel and prospectively collected samples from medically diagnosed patients). The interpretation of these reference assays or the clinical diagnosis would typically involve trained laboratory personnel and/or clinicians, but specific details on their number or qualifications are absent.

4. Adjudication method for the test set:

For comparative testing, the document states: "Discordant samples were further tested by a treponemal EIA kit to determine the final result." This indicates an adjudication method where discrepant results between the RPR and TPPA assays were resolved using a third treponemal EIA.
For the initial comparison between the BioPlex 2200 and the reference assays, if the reference assays yielded an equivocal result, it was assigned to the opposite result than that of the corresponding BioPlex 2200 Syphilis IgG result for the purposes of percent agreement calculation.

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:

This device is an in vitro diagnostic (IVD) assay, not an AI-powered image analysis or diagnostic tool involving "human readers" in the typical sense of an MRMC study. Therefore, no MRMC comparative effectiveness study was done to assess human reader improvement with or without AI assistance. The performance is that of the automated system.

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

Yes, the studies described are standalone performance studies of the BioPlex 2200 Syphilis IgG kit on the BioPlex 2200 Multi-Analyte Detection System. The device is an automated IVD system that performs the assay and provides a result (Reactive, Equivocal, Nonreactive) without human interpretation steps that would define a "human-in-the-loop" performance study. The human intervention would be in operating the machine and interpreting the instrument's final declared result, but not in the diagnostic decision process itself as if it were an AI diagnostic aid.

7. The type of ground truth used:

The ground truth for the test sets was primarily established through a combination of expert consensus based on established reference laboratory assays (RPR, TPPA, and treponemal EIA) and known clinical status/medical diagnosis.

  • For the main comparative testing studies, the "Reference Assays Result" was determined by an algorithm combining RPR and TPPA results, with discordant results resolved by treponemal EIA.
  • For the clinical sensitivity studies (CDC panel and prospectively collected samples), the ground truth was based on "Known Clinical Status" or "medically diagnosed with syphilis infections." While the document doesn't explicitly state "expert consensus" as the method for clinical diagnosis, medical diagnosis inherently involves professional judgment and consensus within the medical community.

8. The sample size for the training set:

The document does not specify a distinct "training set" or its sample size. This is typical for traditional IVD assays, where method development and optimization (analogous to training in machine learning) occur, but a formal, separate "training set" as understood in AI/ML development is not usually detailed in regulatory submissions for these types of devices. The "training" here refers to the internal development and calibration of the assay.

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

As no explicit training set is described in the context of AI/ML, the question of how its ground truth was established is not directly applicable. However, the development of the BioPlex 2200 Syphilis IgG kit would have involved internal validation and optimization using characterized samples to define reactivities and cut-off values. This process would rely on previously established reference methods and clinical samples.

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K063866

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MAR 1 9 2007

BIOPLEX 2200 SYPHILIS IgG 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) Number510(k) Summary Report Date
K063866March 8, 2007

MANUFACTURER INFORMATION

Manufacturer
Manufacturer AddressBio-Rad Laboratories, Inc.Clinical Systems Division4000 Alfred Nobel DriveHercules, CA 94547
Telephone(510) 724-7000
Establishment Registration No.2915274
Owner / OperatorBio-Rad Laboratories, Inc.4000 Alfred Nobel DriveHercules, CA 94547
Owner / Operator No.9929003
Official Correspondent for the BioPlex 2200 EBV IgG
Official Correspondent AddressBio-Rad Laboratories6565 185th Ave NERedmond, WA 98052
Telephone425-881-8300
Establishment Registration No.3022521
Owner / OperatorBio-Rad Laboratories6565 185th Ave NERedmond, WA 98052
Official CorrespondentMr. Christopher Bentsen
Telephone(425) 498-1709
Fax(425) 498-1651

CLASSIFICATION INFORMATION

Classification NameTreponema Pallidum Treponemal Test Reagents
Common Name:Multi-Analyte Detection System Syphilis IgG
Product Trade NameBioPlex 2200 Syphilis IgG on the BioPlex 2200 Multi-AnalyteDetection System
Device ClassClass II
Classification PanelMicrobiology
Regulation Number866.3830

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LEGALLY MARKETED EQUIVALENT (SE) DEVICES

Comparative FDA ClearedPREDICATE DEVICE510(k) NumberDecisionDate
Macro-Vue RPR Card (Becton Dickenson)Pre-AmendmentN/A
Serodia TPPA (Fujirebio Inc.)97150211/13/1997
Trep-Chek Anti-Treponemal EIA (Phoenix Bio-Tech Corp.)00155210/19/2000

DEVICE DESCRIPTION

The Syphilis IgG kit uses multiplex flow immunoassay, a methodology that greatly resembles traditional EIA, but permits simultaneous detection and identification of many antibodies in a single tube.19 Three (3) different populations of dyed beads are coated with recombinant proteins associated with T. pallidum (15kD, 17kD and 47kD). The BioPlex 2200 System combines an aliquot of patient sample, sample diluent, and bead reagent into a reaction vessel. The mixture is incubated at 37°C. After a wash cycle, anti-human IgG antibody, conjugated to phycoerythrin (PE), is added to the dyed beads, and this mixture is incubated at 37°C. The excess conjugate is removed in another wash cycle, and the beads are re-suspended in wash buffer. The bead mixture then passes through the detector. The identity of the dyed beads is determined by the fluorescence of the dyes, and the amount of antibody captured by the antigen is determined by the fluorescence of the attached PE. Raw data is calculated in relative fluorescence intensity (RFI).

Three additional dyed beads, Internal Standard Bead (ISB), Serum Verification Bead (SVB) and a Reagent Blank Bead (RBB) are present in each reaction mixture to verify detector response, the addition of serum or plasma to the reaction vessel and the absence of significant non-specific binding in serum or plasma. Refer to the BioPlex 2200 System Operation Manual for more information.

The system is calibrated using a set of four (4) distinct calibrators vials, supplied separately by Bio-Rad Laboratories. Four (4) vials representing two (2) or three (3) different antibody concentrations are used for calibration. Results are calculated for each of the three (3) antibodies and are compared against their own respective cut-off and are expressed as an antibody index (AI). A single result is reported after completing a composite analysis of all the antibodies (the highest Al value is reported).

KIT COMPONENTS

Syphilis IgG (665-1450). The reagent pack contains supplies sufficient for 100 tests.

VialDescription
Bead SetOne (1) 10 mL vial, containing dyed beads coated with affinity-purified E.coli derived recombinant proteins to T. pallidum (15kD, 17kD, and 47kD),an Internal Standard (ISB), a Serum Verification (SVB), and a ReagentBlank (RBB), with Glycerol and protein stabilizers (bovine) in a MOPS (3-[NMorpholino] propanesulfonic acid) buffer. ProClin® 300 (0.3%) and sodiumazide (<0.1%) as preservatives.
ConjugateOne (1) 5 mL vial, containing murine monoclonal anti-humanIgG/phycoerythrin conjugate and anti-human FXIII/phycoerythrin conjugate,with protein stabilizers (bovine) in a phosphate buffer. ProClin® 300 (0.3%)and sodium azide (<0.1%) as preservatives.
Sample DiluentOne (1) 10 mL vial, containing protein stabilizers (bovine and murine) in atriethanolamine buffer. ProClin® 300 (0.3%) and sodium azide (<0.1%) aspreservatives.

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ADDITIONAL REQUIRED ITEMS, AVAILABLE FROM BIO-RAD

Catalog #Description
663-1400BioPlex 2200 Syphilis IgG Calibrator Set: Four (4) 500 µL vials, containingT. pallidum (15kD, 17kD, and 47kD) antibodies in a human serum matrixmade from defibrinated plasma. ProClin® 300 (0.3%) as a preservative forall calibrators.
663-1430BioPlex 2200 Syphilis IgG Control Set: Two (2) 1.5 mL vials of PositiveControl containing antibodies to T. pallidum 17kD and two (2) 1.5 mL vialsof Positive Control containing antibodies to T. pallidum 15kD and 47kD in ahuman serum matrix made from defibrinated plasma, and two (2) 1.5 mLvials of Negative Control in a human serum matrix made from defibrinatedplasma. ProClin® 300 (0.3%) as a preservative for all controls.
660-0817BioPlex 2200 System Sheath Fluid: Two (2) 4 L bottles containingPhosphate Buffered Saline (PBS). ProClin® 300 (0.3%) and Sodium azide(0.1%) as preservatives.
660-0818BioPlex 2200 System Wash Solution: One (1) 10 L bottle containingPhosphate Buffered Saline (PBS) and Tween 20. ProClin® 300 (0.3%) andSodium azide (0.1%) as preservatives.
660-0000BioPlex 2200 Instrument and Software.

INTENDED USE / INDICATIONS FOR USE

The Bio-Rad Syphilis IgG kit is a multiplex flow immunoassay intended for the qualitative detection of Treponema pallidum IgG antibodies in human serum. The test system, when used in conjunction with non-treponemal based assays, provides serological evidence of infection with T. pallidum. This test system is also indicated for use in confirming reactive test results from nontreponemal based screening assays.

The Syphilis IgG kit is intended for use with the Bio-Rad BioPlex 2200 System.

The BioPlex 2200 Syphilis IgG kit is not intended for use in screening blood or plasma donors.

Warning: A positive result is not useful for establishing a diagnosis of Syphilis. In most situations, such a result may reflect prior treated infection; a negative result can exclude a diagnosis of syphilis except for incubating or early primary disease.

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TECHNOLOGICAL CHARACTERISTICS

The following tables summarize similarities and differences between the BioPlex 2200 Syphilis IgG Kit and the predicate devices used in comparative studies with the BioPlex 2200 Syphilis IgG Kit.

A. BioPlex 2200 EBV IgG Assay vs. Predicate RPR Test

Table 1: Similarities between reagents and materials

Similarities betweenComponents / MaterialsBioPlex 2200 Syphilis IgG KitPredicate RPR Test
ReagentsThe Bead Set reagent containingdyed antigen coated beads reacts withthe patient sample.The Antigen Suspension reagentreacts with the patient sample.

Table 2: Similarities between reagents with regard to function and use

Similarities betweenFunction and UseBioPlex 2200 Syphilis IgG KitPredicate RPR Test
Intended UseAid in the diagnosis of SyphilisAid in the diagnosis of Syphilis

Table 3: Differences between reagents and materials

Differences betweenComponents / MaterialsBioPlex 2200 Syphilis IgG KitPredicate RPR Test
Solid PhaseBead Set reagent - dyed antigencoated beads.None.
ReagentsConjugate, Sample Diluent, WashBuffer.Antigen Suspension.
Sheath FluidSheath Fluid is used to suspend thebead reagent and introduce it into thedetector.Not similar; not utilized in RPRtests.
CalibratorsCalibrators.None.
ControlNegative Control and multi-analytePositive Control.User provided controls withestablished patterns of gradedactivity (optional Control Card Setsavailable)

Table 4: Differences between reagents with regard to function and use

Differences betweenFunction and UseBioPlex 2200 Syphilis IgG KitPredicate RPR Test
Analyte DetectionMulti-analyte qualitative detection ofhuman IgG antibodies to Treponemapallidum.Non-treponemal qualitative andquantitative detection of humanreagin.
MatricesSerum.Serum and Plasma.

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B. BioPlex 2200 EBV IgG Assay vs. Predicate TPPA Test

Table 5: Similarities between reagents and materials

Similarities betweenComponents / MaterialsBioPlex 2200 Syphilis IgG KitPredicate TPPA
ReagentsSample DiluentSample Diluent
ControlsNegative Control and multi-analytePositive ControlNon-reactive Control Serum andPositive Control Serum (containingrabbit antibodies to Treponemapallidum)

Table 6: Similarities between reagents with regard to function and use

Similarities betweenFunction and UseBioPlex 2200 Syphilis IgG KitPredicate TPPA
Intended UseAid in the diagnosis of SyphilisAid in the diagnosis of Syphilis

Table 7: Differences between reagents and materials

Differences betweenComponents / MaterialsBioPlex 2200 Syphilis IgG KitPredicate TPPA
Solid PhaseBead reagent - dyed antigen coatedbeads.None.
ReagentsConjugate, Wash Buffer.Sensitized Particles, UnsensitizedParticles.
Sheath FluidSheath Fluid is used to suspend thebead reagent and introduce it into thedetector.Not similar; not utilized in TPPAtests.
CalibratorsCalibrators.None.

Table 8: Differences between reagents with regard to function and use

Differences betweenFunction and UseBioPlex 2200 Syphilis IgG KitPredicate TPPA
Analyte DetectionMulti-analyte detection of humanIgG antibodies to Treponemapallidum.Detection of human antibodies toTreponema pallidum.
MatricesSerum.Serum and Plasma.

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C. BioPlex 2200 EBV IgG Assay vs. Predicate EIA Test

Similarities betweenComponents / MaterialsBioPlex 2200 Syphilis IgG KitPredicate EIA
ReagentsWash Buffer, Sample DiluentSample Diluent, Wash Buffer
Calibrator(s)CalibratorsCalibrator
ControlsNegative Control and multi-analyte Positive ControlNegative Control and Positive Control

Table 9: Similarities between reagents and materials

Table 10: Similarities between reagents with regard to function and use

Similarities betweenFunction and UseBioPlex 2200 Syphilis IgG KitPredicate EIA
Intended UseQualitative detection of IgGantibodies to Treponema pallidum.Qualitative detection of IgGantibodies to Treponema pallidum.

Table 11: Differences between reagents and materials

Differences betweenComponents / MaterialsBioPlex 2200 Syphilis IgG KitPredicate EIA
Solid PhaseBead reagent - dyed antigen coatedbeads.96 well microplate - antigen coatedmicrowells.
ReagentsConjugate: Anti-human IgG /Phycoerythrin.Conjugate: goat anti-human IgGhorseradish peroxidase, Substrate(TMB), Stop Solution.
Sheath FluidSheath Fluid is used to suspend thebead reagent and introduce it into thedetector.Not similar; not utilized in EIA's.

Table 12: Differences between reagents with regard to function and use

Differences betweenFunction and UseBioPlex 2200 Syphilis IgG KitPredicate EIA
Analyte DetectionMulti-analyte detection of humanIgG antibodies to Treponemapallidum.Detection of human IgG antibodiesto Treponema pallidum.
MatricesSerum.Serum and Plasma.

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PERFORMANCE SUMMARY

A. Expected Values

Prevalence

Expected values for the Syphilis IgG kit are presented by age and gender in the following tables for serum samples from unselected hospitalized patients (N=300), serum samples from patients who had a syphilis test ordered (N=500), and serum samples from unselected pregnant women (N=497). For all analytes, results of ≤0.8 Ai are nonreactive, 0.9 and 1.0 Al are equivocal, and ≥1.1 Al are reported as reactive.

AgeGenderReactiveEquivocalNonreactiveTotal
N%N%N%N
0-9 years of ageF00.0%00.0%00.0%0
M00.0%00.0%1100%1
10-19 years of ageF00.0%00.0%3100%3
M00.0%00.0%9100%9
20-29 years of ageF15.3%00.0%1894.7%19
M00.0%00.0%16100%16
30-39 years of ageF18.3%00.0%1191.7%12
M310.0%00.0%2790.0%30
40-49 years of ageF310.7%00.0%2589.3%28
M49.3%00.0%3990.7%43
50-59 years of ageF27.4%00.0%2592.6%27
M716.3%00.0%3683.7%43
60-69 years of ageF18.3%00.0%1191.7%12
M419.0%00.0%1781.0%21
70-79 years of ageF436.4%00.0%763.6%11
M218.2%00.0%981.8%11
80-89 years of ageF00.0%00.0%6100%6
M00.0%00.0%3100%3
> 89 years of ageF125.0%00.0%375.0%4
M00.0%00.0%1100%1
Total3311.0%00.0%26789.0%300

Table 13. Samples From Unselected Hospitalized Patients (N=300)

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AgeGenderReactiveEquivocalNonreactiveTotal
N%N%N%N
< 10 years of ageF00.0%00.0%00.0%0
< 10 years of ageM00.0%00.0%1100%1
10-19 years of ageF00.0%00.0%31100%31
10-19 years of ageM00.0%00.0%1100%1
20-29 years of ageF34.0%00.0%7296.0%75
20-29 years of ageM414.8%00.0%2385.2%27
30-39 years of ageF36.8%00.0%4193.2%44
30-39 years of ageM510.9%24.3%3984.8%46
40-49 years of ageF310.3%00.0%2689.7%29
40-49 years of ageM2321.5%00.0%8478.5%107
50-59 years of ageF310.0%00.0%2790.0%30
50-59 years of ageM1826.5%11.5%4972.1%68
60-69 years of ageF214.3%00.0%1285.7%14
60-69 years of ageM318.8%00.0%1381.3%16
70-79 years of ageF133.3%00.0%266.7%3
70-79 years of ageM350.0%00.0%350.0%6
80-89 years of ageF00.0%00.0%1100%1
80-89 years of ageM00.0%00.0%1100%1
Total7114.2%30.6%42685.2%500

Table 14. Serum Samples From Patients Who Had a Syphilis Test Ordered (N=500)

Table 15. Serum Samples From Unselected Pregnant Women (N=497)

AgeReactiveEquivocalNonreactiveTotal
N%N%N%
10-19 years of age00.0%00.0%42100%42
20-29 years of age31.4%00.0%20898.6%211
30-39 years of age31.5%00.0%19398.5%196
40-49 years of age00.0%00.0%47100%47
Unknown00.0%00.0%1100%1
Total61.2%00.0%49198.8%497

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B. Reproducibility Studies

A reproducibility panel, consisting of seven (7) panel members for each of the three (3) recombinant proteins associated with T. pallidum (15kD, 17kD and 47kD) was prepared by Bio-Rad Laboratories. Two (2) of the seven (7) members for each analyte had high positive levels of antibodies, and two (2) had positive antibody levels near the cutoff, additionally, there were two (2) high negative panel members and one (1) low negative panel member for each analyte. In addition, one positive control (antibody positive for 15kD and 47kD), one positive control antibody positive for 17kD) and a negative control (antibody negative for all analytes) were also tested. Reproducibility testing was performed at each of three (3) US testing facilities on a total of three (3) lots of the Syphilis IgG kit, three (3) lots of the Syphilis IgG Calibrator Set, and three (3) lots of the Syphilis IgG Control Set. Each testing facility evaluated reproducibility using one (1) kit lot of the Syphilis IgG kit with matched calibrators and controls. The panels were provided to each of the testing sites. Each of the seven (7) panel members and positive and negative controls was tested in duplicate (x2) on two (2) runs per day for three (3) days at each of three (3) US testing facilities using one (1) lot of BioPlex 2200 Syphilis IgG Reagent Pack and one (1) lot of Syphilis IgG Calibrator Set (2 times x 2 runs x 3 days x 3 sites = 36 replicates per panel member and controls). The data were analyzed for intra-assay and inter-assay reproducibility according to the principles described in the Clinical Laboratory Standards Institute guidance EP5-A2, revised November 2004 and ISO/TR 22971:2205. The standard deviation (SD) and percent coefficient of variation (%CV) were calculated. Positive results can be found in Table 16.

Syphilis IgGPanel MembersSampleNGrandMeanAIWithin-RunBetween-RunBetween-DayBetween-Site*Total
SD%CVSD%CVSD%CVSD%CVSD%CV
T. pallidumrecombinant 15kDHigh Positive 1363.00.13.3%0.14.4%0.12.3%0.310.4%0.412.0%
High Positive 2363.30.12.2%0.12.4%0.24.7%0.27.2%0.39.2%
Low Positive 1361.40.03.0%0.14.7%0.110.1%0.215.5%0.319.3%
Low Positive 2361.30.02.2%0.03.6%0.03.1%0.214.0%0.215.0%
Positive Control362.20.12.9%0.12.2%0.00.0%0.523.3%0.523.6%
T. pallidumrecombinant 17kDHigh Positive 1363.20.13.1%0.24.8%0.00.0%0.37.9%0.39.7%
High Positive 2362.80.12.8%0.14.2%0.12.5%0.28.2%0.39.9%
Low Positive 1361.30.03.7%0.01.9%0.15.5%0.16.2%0.19.3%
Low Positive 2361.30.02.5%0.03.7%0.16.0%0.15.6%0.19.4%
Positive Control362.30.13.2%0.01.5%0.13.5%0.313.3%0.314.2%
T. pallidumrecombinant 47kDHigh Positive 1363.80.12.3%0.11.9%0.25.2%0.37.8%0.49.9%
High Positive 2363.60.12.4%0.12.3%0.00.0%0.37.5%0.38.2%
Low Positive 1361.20.03.8%0.02.4%0.15.6%0.111.1%0.213.2%
Low Positive 2361.30.02.9%0.03.2%0.14.1%0.211.9%0.213.3%
Positive Control362.30.14.0%0.00.0%0.00.0%0.519.5%0.519.9%

Table 16. Reproducibility: BioPlex 2200 Syphilis IgG

*Between site variance includes between lot variance.

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C. Precision Studies

A precision panel, consisting of nine (9) panel members for each of the three (3) recombinant proteins associated with T. pallidum 5kD, 17kD and 47kD) was prepared by Bio-Rad Laboratories. Two (2) of the nine (9) panel members had high reactive levels of the ntibodies, two (2) had low reactive levels of the antibodies, and two (2) had antibody levels near the cut-off; additionally there were two (2) high negative panel members and one (1) low negative panel member for each analyte. Precision testing was performed at Bio-Rad Laboratories on one lot of the Syphilis IgG kit, one lot of the Syphilis IgG Calibrator Set and one lot of the Syphilis IgG Control Set. Each of the nine (9) panel members was tested in duplicate (x2) on two (2) runs per day for twenty (20) days using one (1) lot of Syphilis IgG kit, one (1) lot of Syphilis IgG Calibrator Set and one (1) lot of Syphilis IgG Control Set (2 times x 2 runs x 20 days = 80 replicates per panel member). The data were analyzed for intra-assay and inter-assay precision according to the principles described in the Clinical Laboratory Standards Institute guidance EP5-A2, revised November 2004 and ISO/TR 22971:2205. The standard deviation (SD) and percent coefficient of variation (%CV) were calculated. Results can be found in Tables 17 - 19.

Syphilis 15kDPanel MembersSampleN*MeanWithin-RunBetween-DayBetween-RunTotal
SD%CVSD%CVSD%CVSD%CV
Negative800.00.02N/A0.00N/A0.00N/A0.02N/A
High Negative 1800.50.012.3%0.036.6%0.036.6%0.048.3%
High Negative 2800.50.024.0%0.036.7%0.000.0%0.059.6%
Near Cut-off 1801.00.043.5%0.077.0%0.033.1%0.098.4%
Near Cut-off 2801.00.043.8%0.066.5%0.033.3%0.087.8%
Low Positive 1801.40.053.9%0.128.6%0.054.0%0.1410.4%
Low Positive 2801.30.053.5%0.107.9%0.054.1%0.139.6%
High Positive 1803.10.113.7%0.227.3%0.113.6%0.279.0%
High Positive 2803.40.072.1%0.175.0%0.185.2%0.267.6%

Table 17. Precision Results; BioPlex 2200 Syphilis IgG 15kD

N/A = No precision specification established for samples below cut-off.

Table 18. Precision Results; BioPlex 2200 Syphilis IgG 17kD
---------------------------------------------------------------------
Syphilis 17kDSampleMeanWithin-RunBetween-DayBetween-RunTotal
Panel MembersNSD%CVSD%CVSD%CVSD%CV
Negative800.00.00N/A0.00N/A0.00N/A0.00N/A
High Negative 1800.50.047.0%0.036.0%0.036.0%0.0610.8%
High Negative 2800.50.036.0%0.048.4%0.036.0%0.0611.5%
Near Cut-off 1801.00.033.3%0.076.9%0.033.1%0.087.9%
Near Cut-off 2801.00.033.1%0.055.3%0.044.3%0.087.3%
Low Positive 1801.30.064.3%0.097.5%0.043.5%0.129.4%
Low Positive 2801.30.043.3%0.086.3%0.032.4%0.107.4%
High Positive 1803.20.113.3%0.268.2%0.082.4%0.309.1%
High Positive 2802.90.072.5%0.207.1%0.093.1%0.238.2%

N/A = No precision specification established for samples below cut-off.

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Within-RunBetween-DayBetween-RunTotal
Syphilis 47kDPanel MembersSampleNMeanSD%CVSD%CVSD%CVSD%CV
Negative800.00.00N/A0.00N/A0.00N/A0.00N/A
High Negative 1800.60.011.9%0.035.4%0.000.0%0.045.9%
High Negative 2800.60.035.2%0.000.0%0.035.1%0.057.4%
Near Cut-off 1801.10.032.4%0.044.3%0.033.0%0.065.7%
Near Cut-off 2801.10.043.1%0.054.8%0.032.8%0.076.4%
Low Positive 1801.20.054.1%0.086.8%0.032.6%0.108.5%
Low Positive 2801.40.053.4%0.096.5%0.075.2%0.128.8%
High Positive 1803.40.061.8%0.216.2%0.082.5%0.237.0%
High Positive 2803.80.061.7%0.184.7%0.143.9%0.246.3%

Table 19. Precision Results; BioPlex 2200 Syphilis IgG 47kD

N/A = No precision specification established for samples below cut-off.

D. Comparative Testing

Comparative Testing

Comparison of Syphilis IgG and Non-treponemal (RPR) and TPPA test

The performance of the Syphilis IgG kit was evaluated against corresponding reference (RPR and TPPA) assays. Results were interpreted according to Table 20 below. Discordant samples were further tested by a treponemal EIA kit to determine the final result.

Non-treponemalResult (RPR)TreponemalResult (TPPA)Reference Assays ResultTreponemal (EIA)ResultFinal ReferenceAssays Result
NonreactiveNonreactiveNegativeN/ANegative
NonreactiveReactiveDiscordantNegativeNegative
EquivocalEquivocal
PositivePositive
ReactiveNonreactiveDiscordantNegativeNegative
Equivocal
Positive
ReactiveReactivePositiveN/APositive

Table 20. Reference Syphilis Testing Algorithm

A total of 1,750 serum samples were evaluated at three (3) U.S. clinical testing sites. The results can be observed in Tables 21 - 27 for banked serum samples from patients who had a syphilis test ordered; from unselected pregnant women; from serum samples requested to be RPR/TPPA reactive; from pregnant women requested to be treponemal assay positive; from pregnant women requested to be RPR/TPPA nonreactive; and from patients medically diagnosed with syphilis. For the purposes of percent agreement, reference assay equivocal results were assigned to the opposite result than that of the corresponding BioPlex 2200 Syphilis IgG result. Results are shown in Tables 21 - 27.

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·

:

BioPlex 2200 Syphilis IgG
ReactiveEquivocalNonreactiveTotalPositive (+)% Agreement95%ConfidenceIntervalNegative (-)% Agreement95%ConfidenceInterval
Reference AssaysResultPositive460046100%(46/46)92.0 - 100%93.8%(426/454)91.2 - 95.7%
Equivocal3*003
Negative22**3426451
Total713426500

Table 21. Serum Samples From Patients Who Had a Syphilis Test Ordered (N=500)

  • Three (3) BioPlex 2200 Syphills IgG reactive samples were RPR nonreactive, TPPA reactive and treponemal EIA equivocal.

** Of 22 samples with reactive results on the BioPlex 2200 Syphilis IgG assay, 16 were RPR and TPPA nonreactive, and 6 samples were RPR reactive, TPPA nonreactive and treponemal EIA negative.

Table 22. Unselected Serum Samples From Pregnant Women (N=497)
THE LAND SHEET AND FORMICAL CAR LEASERS"WITH A A A A B A C A C A C A L A L A L E S A C S A C S A C S A C A C A C A C A C A C A C A C A C A C A . A . A . A
Reference Assays ResultReactiveEquivocalNonreactiveTotalPositive (+) % Agreement95% Confidence IntervalNegative (-) % Agreement95% Confidence Interval
Positive5005
Equivocal0000100%(5/5)56.5 - 100%99.8%(491/492)98.9 - 100.%
Negative1*0491492
Total60491497
  • One (1) sample with a BioPlex 2200 reactive result was RPR and TPPA nonreactive.
Reference AssaysResultReactiveEquivocalNonreactiveTotalPositive (+)% Agreement95%ConfidenceInterval
Positive24900249100%(249/249)98.5 - 100%
Equivocal0000
Negative0011
Total24901250

:

Table 23. Serum Samples Requested to be RPR and TPPA Reactive (N=250)

:

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Table 24. Serum Samples From Pregnant Women Requested to be Treponemal Assay Positive (N=183)

BioPlex 2200 Syphilis IgG
ReactiveEquivocalNonreactiveTotalPositive (+)% Agreement95%ConfidenceInterval
Reference AssaysResultPositive16600166
Equivocal4*004100%(166/166)97.7-100%
Negative8**0513
Total17805183
  • Four ( 4) BioPlex 2200 Syphilis IgG reactive samples were RPR nonreactive, TPPA reactive and treponemal EIA equivocal.

** Of eight (8) BioPlex 2200 Syphilis IgG reactive samples, 1 sample was RPR and TPPA nonreactive and 7 were RPR reactive, TPPA nonreactive and treponemal EIA negative.

Table 25. Serum Samples From Pregnant Women Requested to be RPR/TPPA Nonreactive
(N=250)
Reference AssaysResultBioPlex 2200 Syphilis IgG
ReactiveEquivocalNonreactiveTotalNegative (+)% Agreement95%ConfidenceInterval
Positive000096.5 -99.6%
Equivocal000098.8%
Negative3*0247250(247/250)
Total30247250
  • Three (3) BioPlex 2200 Syphilis IgG reactive samples were RPR and TPPA nonreactive.

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Table 26. Combined Serum Samples From 183 Pregnant Women Requested to be Treponemal Assay Positive and 250 Pregnant Women Requested to be RPR/TPPA Nonreactive (N=433)

BioPlex 2200 Syphilis IgG
ReactiveEquivocalNonreactiveTotalPositive (+)% Agreement95%ConfidenceIntervalNegative (-)% Agreement95%ConfidenceInterval
Reference AssaysResultPositive16600166100%(166/166)97.7 -100.0%94.4%(252/267)90.9 - 96.6%
Equivocal4*004
Negative11**0252263
Total1810252433
  • Four (4) BioPlex 2200 Syphilis IgG reactive samples were RPR reactive, TPPA nonreactive and treponemal EIA equivocal.

** Of 11 BioPlex 2200 Syphilis IgG reactive samples, 4 samples were RPR and TPPA nonreactive, and 7 samples were RPR nonreactive, TPPA reactive and treponemal EIA negative.

BioPlex 2200 Syphilis IgG
ReactiveEquivocalNonreactiveTotalPositive (+)% Agreement95%ConfidenceInterval
Reference AssaysResultPositive630063100.0%(63/63)94.2 - 100%
Equivocal1*001
Negative3**036
Total670370

Table 27. Serum Samples From Patients Medically Diagnosed With Syphilis (N=70)

  • One (1) sample with BioPlex 2200 Syphilis IgG reactive results was RPR nonreactive, TPPA reactive and treponemal EIA equivocal.

** Three (3) samples with BioPlex 2200 Syphilis IgG reactive results were RPR and TPPA nonreactive.

As can be seen in the table above, 95.7% (67/70) of the patients medically diagnosed with syphilis infection were reactive when tested with the BioPlex 2200 Syphilis IgG test, in comparison to 90% (63/70) by reference assay testing.

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Correlation with Known HIV-1 Positive Samples

Performance of the BioPlex 2200 Syphilis IgG kit was evaluated in two hundred twenty (220) banked known HIV-1 positive serum samples. Results were compared to reference assay results for RPR/TPPA and if applicable, treponemal EIA.

Of the 220 known HIV-1 positive serum samples, one hundred eighty-one (181) were negative by reference assay testing and one hundred twenty-three (123) samples were negative by BioPlex 2200 Syphilis IgG testing, for 68.0% (123/181) negative agreement with a 95% confidence interval of 60.8-74.3%. Of the one hundred eighty-one (181) samples were equivocal by reference assay testing (and were considered negative for the purposes of percent agreement calculations) and nineteen (19) samples were equivocal by BioPlex 2200 Syphilis IgG testing (and were considered positive for the purposes of percent agreement calculations).

Of the 220 known HIV-1 positive serum samples, thirty-nine (39) were positive by reference assay testing and by BioPlex 2200 Syphilis IgG testing, for 100% (39/39) positive agreement with a 95% confidence interval of 91.0-100%.

Correlation with Disease Stages and Clinical Sensitivity

The performance of the Syphilis IgG kit was evaluated at one clinical testing site using a CDC panel of banked frozen characterized sera (N=140), with known disease state and treatment status. Panel samples were from treated and untreated patients with primary, secondary or latent infections. Performance of the Syphilis IgG kit for the CDC panel was compared to reference assay results using commercially available (RPR, TPPA and if required treponemal EIA) kits by known clinical status. Results are shown in Tables 28 - 30 below.

Reference Assays Result
KnownClinicalStatusPositiveBioPlex 2200Syphilis IgGEquivocalBioPlex 2200Syphilis IgGNegativeBioPlex 2200Syphilis IgGTotal
REQVNRREQVNRREQVNR
UntreatedPrimary100000000212
Secondary100000000010
Latent80000000513
TreatedPrimary150000000116
Secondary360000000036
Latent490000000453
Total128000000012140

Table 28. BioPlex 2200 Syphilis IgG vs. Reference Assays: Comparison by Known Clinical Status

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Known Clinical StatusNBioPlex 2200 Syphilis IgGReference Assays Result
ReactiveEquivocalNonreactiveClinical Sensitivity %PositiveEquivocalNegativeClinical Sensitivity %
UntreatedPrimary12100283.3%(10/12)100283.3%(10/12)
Secondary101000100%(10/10)1000100%(10/10)
Latent1380561.5%(8/13)80561.5%(8/13)
TreatedPrimary16150193.8%(15/16)150193.8%(15/16)
Secondary363600100%(36/36)3600100%(36/36)
Latent53490492.5%(49/53)490492.5%(49/53)
Total14012801291.4%(128/140)12801291.4%(128/140)

Table 29. Bio-Rad Syphilis IgG vs. a CDC Panel of Characterized Sera (N=140)

Table 30. BioPlex 2200 Syphilis IgG vs. Reference Assays: Percent Agreement by Known
Clinical Status
Known Clinical StatusNPositive Agreement95% Confidence Interval
UntreatedPrimary12(10/10)72.2 - 100%
Secondary10(10/10)72.2 - 100%
Latent13(8/8)67.5 - 100%
TreatedPrimary16(15/15)79.6 - 100%
Secondary36(36/36)90.3 - 100%
Latent53(49/49)91.8 - 100%
Total140(128/128)97.1 - 100%

The performance of the Syphilis IgG kit was further evaluated at one clinical testing site using banked prospectively collected serum samples from treated and untreated patients with primary and secondary syphilis infections (N=10). Performance of the Syphilis IgG kit in the 10 samples was compared to a corresponding composite result using commercially available (RPR, TPPA and if required treponemal EIA) kits by known clinical status. Results are shown in Tables 31 - 33 below.

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Table 31. BioPlex 2200 Syphilis IgG vs. Reference Assays: Comparison by Known Clinical Status

Reference Assays Result
KnownClinicalStatusPositiveBioPlex 2200Syphilis IgGEquivocalBioPlex 2200Syphilis IgGNegativeBioPlex 2200Syphilis IgGTotal
REQVNRREQVNRREQVNR
UntreatedPrimary0000001001
Secondary0000000000
TreatedPrimary2000000002
Secondary7000000007
Total90000010010

Table 32. Bio-Rad Syphilis IgG vs. Prospectively Collected Serum Samples With Known Clinical Status (N=10)

Known ClinicalStatusNBioPlex 2200 Syphilis IgGClinical Sensitivity %95% Confidence IntervalReference Assays ResultClinical Sensitivity %95% Confidence Interval
ReactiveEquivocalNonreactivePositiveEquivocalNegative
UntreatedPrimary1100100%(1/1)20.6 - 100%0010.0%(0/1)N/A*
Secondary0000N/A*N/A*000N/A*N/A*
TreatedPrimary2200100%(2/2)34.2 - 100%200100%(2/2)34.2 - 100%
Secondary7700100%(7/7)64.5 - 100%700100%(7/7)64.5 - 100%
Total101000100%(10/10)72.2 - 100%90190.0%(9/10)59.5 - 98.2%
  • In cases where agreement resulted in a numerator of zero (0), 95% confidence interval could not be calculated; in cases where agreement resulted in (0/0) samples, percent and 95% confidence interval could not be calculated.

Table 33. BioPlex 2200 Syphilis IgG vs. Reference Assays: Percent Agreement by Known Clinical Status

Known Clinical StatusNPositive Agreement95% Confidence Interval
UntreatedPrimary1(0/0)N/A*
Secondary0(0/0)N/A*
TreatedPrimary2(2/2)100%34.2 - 100%
Secondary7(7/7)100%64.5 - 100%
Total10(9/9)100%70.1 - 100%
  • In cases where agreement resulted in (0/0) samples percent and 95% confidence intervals could not be calculated.

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The results from testing the CDC panel of samples from patients with treated and untreated primary, secondary and latent syphilis infections (N=140); and the banked prospectively collected samples from treated and untreated patients with primary and secondary syphilis infections (N=10), were combined and results are presented in Tables 34 - 36 below.

Table 34. BioPlex 2200 Syphilis IgG vs. Reference Assays: Combined Comparison By Known
Clinical Status
KnownClinicalStatusPositiveBioPlex 2200Syphilis IgGEquivocalBioPlex 2200Syphilis IgGNegativeBioPlex 2200Syphilis IgGTotal
REQVNRREQVNRREQVNR
UntreatedPrimary100000010213
Secondary100000000010
Latent80000000513
TreatedPrimary170000000118
Secondary430000000043
Latent490000000453
Total137000001012150
Table 35. BioPlex 2200 Syphilis IgG vs. Combined CDC Panel and Prospectively Collected
Samples With Known Clinical Status (N=150)
Known ClinicalStatusNBioPlex 2200 Syphilis IgGReference Assays Result
ReactiveEquivocalNonreactiveClinicalSensitivity %95%ConfidenceIntervalReactiveEquivocalNonreactiveClinicalSensitivity %95%ConfidenceInterval
UntreatedPrimary13110284.6%(11/13)57.8 - 95.7%100376.9%(10/13)49.7 - 91.8%
Secondary101000100%(10/10)72.2 - 100%1000100%(10/10)72.2 - 100%
Latent1380561.5%(8/13)35.5 - 82.3%80561.5%(8/13)35.5 - 82.3%
TreatedPrimary18170194.4%(17/18)74.2 - 99.0%170194.4%(17/18)74.2 - 99.0%
Secondary434300100%(43/43)91.8 - 100%4300100%(43/43)91.8 - 100%
Latent53490492.5%(49/53)82.1 - 97.0%490492.5%(49/53)82.1 - 97.0%
Total15013801292.0%(138/150)86.5 - 95.4%13701389.5%(137/150)86.5 - 94.9%
  • In cases where agreement resulted in (0/0) samples, sensitivity and 95% confidence intervals could not be calculated.

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Table 36. BioPlex 2200 Syphilis IgG vs. Reference Assays: Combined Percent Agreement By Known Clinical Status

Known Clinical StatusNPositive Agreement95% Confidence Interval
UntreatedPrimary13(10/10)100%72.2 - 100%
Secondary10(10/10)100%72.2 - 100%
Latent13(8/8)100%67.5 - 100%
TreatedPrimary18(17/17)100%81.6 - 100%
Secondary43(43/43)100%91.8 - 100%
Latent53(49/49)100%92.7 - 100%
Total150(137/137)100%97.3 - 100%

Diagnostic Screening Results

The results presented in the preceding tables demonstrate that BioPlex 2200 Syphilis IgG can be used for the qualitative detection of antibodies to Treponema pallidum in human serum when used as a diagnostic screening test.

BioPlex 2200 Syphilis IgG Reactive Samples

• In the banked purchased requested to be RPR/TPPA reactive samples (N=250). 249 samples were BioPlex 2200 Syphilis IgG reactive. Of those 249 samples, 100% (249/249) were RPR reactive.

• In the banked purchased samples from unselected pregnant women (N=497), 6 samples were BioPlex 2200 Syphilis IgG reactive. Of those 6 samples, 33.3% (2/6) were RPR reactive.

• In the banked samples from patients with a syphilis test ordered (N=500). 71 samples were BioPlex 2200 Syphilis IgG reactive. Of those 71 samples, 28.2% (20/71) were RPR reactive.

• In the banked purchased samples from pregnant women requested to be treponemal assay positive (N=183), 178 samples were BioPlex 2200 Syphilis IgG reactive. Of those 178 samples, 24.7% (44/178) were RPR reactive.

• In the banked purchased samples from pregnant women requested to be RPR/TPPA nonreactive (N=250), 3 of the samples were BioPlex 2200 Syphilis IgG reactive. Of those 3 samples, none were RPR reactive.

• In the banked prospectively collected samples from patients with medically diagnosed syphilis infections (N= 70), 67 of the samples were BioPlex 2200 Syphilis IgG reactive. Of those 67 samples, 86.6% (58/67) were RPR reactive.

· In the CDC panel of well characterized samples from treated patients with primary, secondary or latent syphilis infection (N=140), 128 of the samples were BioPlex 2200 Syphilis IgG reactive. Of those 128 samples, 99.2% (127/128) were RPR reactive.

• In the banked prospectively collected samples from treated patients with primary or secondary syphilis infection (N=10), 10 of the samples were BioPlex 2200 Syphilis IgG reactive. Of those 10 samples, 100% (10/10) were RPR reactive.

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Diagnostic Confirmatory Results

Results from testing with the BioPlex 2200 Syphilis IgG are presented below to demonstrate its utility as a diagnostic confirmatory test. This test also confirms reactive results from nontreponemal based screening assays.

RPR Reactive Samples

• In the banked purchased samples from unselected pregnant women (N=497), 4 samples were RPR reactive. Of those 4 samples, 50% (2/4) were TPPA reactive and 50% (2/4) were BioPlex 2200 Syphilis IqG reactive.

• In the banked purchased requested to be RPR/TPPA reactive samples (N=250), 250 samples were RPR reactive. Of those 250 samples, 99.6% (249/250) were TPPA reactive and 99.6% (249/250) were BioPlex 2200 Syphilis IgG reactive.

· In the banked samples from patients with a syphilis test ordered (N=500). 20 samples were RPR reactive. Of those 20 samples, 90% (18/20) were TPPA reactive and 100% (20/20) were BioPlex 2200 Syphilis IgG reactive.

• In the banked purchased samples from pregnant women requested to be treponemal assav positive (N=183), 44 samples were RPR reactive. Of those 44 samples, 100% (44/44) were reactive with the TPPA and 100% (44/44) were reactive with the BioPlex 2200 Syphilis IgG test.

· In the banked purchased samples from pregnant women requested to be RPR/TPPA nonreactive (N=250), 3 of the samples were RPR reactive. None of the samples were TPPA or BioPlex 2200 Syphilis IgG reactive.

· In the banked prospectively collected samples from patients with medically diagnosed syphilis infections (N= 70), 58 of the samples were RPR reactive. Of those 58 samples, 100% (58/58) were reactive with the TPPA and 100% (58/58) were reactive with the BioPlex 2200 Syphilis IgG test.

• In the CDC panel of well characterized samples from treated patients with primary, secondary or latent syphilis infection (N=140), 138 of the samples were RPR reactive, Of those 138 samples, 92% (127/138) were reactive with TPPA and 92% (127/138) were reactive with the BioPlex 2200 Syphilis IgG test.

• In the banked prospectively collected samples from treated patients with primary or secondary syphilis infection (N=10), 10 of the samples were RPR reactive. Of those 10 samples, 90% (9/10) were TPPA reactive and 100% (10/10) were BioPlex 2200 Syphilis IgG reactive.

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E. Cross-Reactivity

A cross-reactivity study was performed to determine if samples from various disease states and other potentially interfering factors interfere with test results when tested with the BioPlex 2200 Syphilis IgG kit. A panel of ten (10) specimens positive for each cross reactant were evaluated for possible cross reactivity with the BioPlex 2200 Syphilis IgG kit. The test specimens were also evaluated by TPPA, and where BioPlex 2200 Syphilis IgG results did not agree with TPPA, samples were further tested by RPR and a commercially available EIA. The results demonstrated that the various disease state samples evaluated do not cross react with the BioPlex 2200 Syphilis IgG kit. Most of the samples evaluated were high positive for each disease state. The majority of all samples that elicited a positive result were also confirmed positive by the another treponemal antibody test (TPPA), indicating reactivity to Syphilis (T. pallidum) IgG antibodies rather than cross reactivity. Results can be found in Table 37.

CrossReactivesNMethodSyphilis IgGCrossReactivesNMethodSyphilis IgG
ANA10BioPlex 22003RheumatoidFactor10BioPlex 22000
TPPA2TPPA0
Discrepants1Discrepants0
dsDNA10BioPlex 22000CMV IgG10BioPlex 22000
TPPA0TPPA0
Discrepants0Discrepants0
HCV10BioPlex 22003HIV10BioPlex 22002
TPPA3TPPA2
Discrepants0Discrepants0
E. Coli4*.+++BioPlex 22000HTLV10BioPlex 22000
TPPAN/ATPPA0
Discrepants0Discrepants0
HSV-1 IgG10BioPlex 22001Pregnantwomen10BioPlex 22000
TPPA0TPPA0
Discrepants1Discrepants0
Lyme IgGBorreliaburgdorferi10BioPlex 22001HSV-2 IgG10BioPlex 22001
TPPA1TPPA1
Discrepants0Discrepants0
VZV IgG10BioPlex 22000Lyme IgGAfzelli / Garnii49*.+BioPlex 22001
TPPA0TPPA1++
Discrepants0Discrepants0
Hyper-gamma-globulinemia10BioPlex 22002EBV IgG10BioPlex 22000
TPPA1TPPA0
Discrepants1Discrepants0
Leptospirosis7BioPlex22002Small Pox10+++BioPlex 22000
Predicate2TPPAN/A
Discrepants0Discrepants0

Table 37. Cross-Reactivity

  • Due to limited availability of samples, only four E. coli specimens were evaluated.

** Additional samples were tested to evaluate the various lyme strains.

† Only positive samples were tested by the predicate.

ttt Testing was only performed on the BioPlex 2200 Syphilis IgG assay.

tt Sample was negative by TPPA but positive by both RPR and EIA

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Food and Drug Administration 2098 Gaither Road Rockville MD 20850

Mr. David Bhend Regulatory Affairs Associate Bio-Rad Laboratories Diagnostics Group 6565 185th Avenue NE Redmond, WA 98052

MAR 1 9 2007

Re: K063866

Trade/Device Name: BioPlex 2200 Syphilis IgG kit on the BioPlex 2200 Multi-Analyte Detection System Regulation Number: 21 CFR 866.3830 Regulation Name: Treponema pallidum treponemal test reagents Regulatory Class: Class II Product Code: LIP Dated: March 8, 2007 Received: March 9, 2007

Dear Mr. Bhend:

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 either class II (Special Controls) or class III (PMA), 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.

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); and good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820).

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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 information about the application of labeling requirements to your device, or questions on the promotion and advertising of your device, please contact the Office of In Vitro Diagnostic Device Evaluation and Safety at (240)276-0450. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21CFR Part 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers, International and Consumer 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.

Sally artman

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

Enclosure

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INDICATIONS FOR USE STATEMENT

510(k) Number (if known): K063866

BioPlex 2200 Syphilis IgG kit on the Device Name: BioPlex 2200 Multi-Analyte Detection System

Indications for Use:

The Bio-Rad Syphilis IgG kit is a multiplex flow immunoassay intended for the qualitative detection of Treponema pallidum IgG antibodies in human serum. The test system, when used in conjunction with non-treponemal based assays, provides serological evidence of infection with T. pallidum. This test system is also indicated for use in confirming reactive test results from non-treponemal based screening assays.

The Syphilis IgG kit is intended for use with the Bio-Rad BioPlex 2200 System.

The BioPlex 2200 Syphilis IgG kit is not intended for use in screening blood or plasma donors.

Warning: A positive result is not useful for establishing a diagnosis of Syphilis. In most situations, such a result may reflect prior treated infection; a negative result can exclude a diagnosis of syphilis except for incubating or early primary disease.

x Prescription Use: (Per 21 CFR 801.109)

AND/OR

Over-The-Counter Use: (Optional Format 1-2-96)

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

Concurrence of CDRH, Office of Device Evaluation (ODE)

Evelyn M. Poole

on Sign-Off

Office of In Vitro Diagnostic Device Evaluation and Safety

Page 1 of 1

510(k) K063866

§ 866.3830

Treponema pallidum treponemal test reagents.(a)
Identification. Treponema pallidum treponemal test reagents are devices that consist of the antigens, antisera and all control reagents (standardized reagents with which test results are compared) which are derived from treponemal sources and that are used in the fluorescent treponemal antibody absorption test (FTA-ABS), theTreponema pallidum immobilization test (T.P.I.), and other treponemal tests used to identify antibodies toTreponema pallidum directly from infecting treponemal organisms in serum. The identification aids in the diagnosis of syphilis caused by bacteria belonging to the genusTreponema and provides epidemiological information on syphilis.(b)
Classification. Class II (performance standards).