CHLAMYDIA IGG ELISA TEST SYSTEM

K962558 · Armkel, LLC · LJC · Feb 24, 1997 · Microbiology

Device Facts

• Record ID: K962558
• Device Name: CHLAMYDIA IGG ELISA TEST SYSTEM
• Applicant: Armkel, LLC
• Product Code: LJC · Microbiology
• Decision Date: Feb 24, 1997
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.3120
• Device Class: Class 1

Intended Use

The Chlamydia IgG ELISA kit is an Enzyme-Linked Immunosorbent Assay (ELISA) for qualitative detection of IgG antibodies in human serum to Chlamydia for the determination of immunological experience.

Device Story

The Chlamydia IgG ELISA kit is an in vitro diagnostic assay for detecting IgG antibodies to Chlamydia in human serum. The device utilizes purified Chlamydia antigen (strain LGV II) immobilized on microtiter wells. Patient serum is added; if specific IgG antibodies are present, they bind to the antigen. After washing, an enzyme-labeled anti-human IgG conjugate is added, followed by a substrate solution. The resulting color change, measured photometrically, provides an indirect quantitative measurement of specific antibody levels. The test is performed in clinical laboratory settings by trained laboratory personnel. Results assist clinicians in assessing a patient's immunological experience with Chlamydia. The device provides a standardized method for antibody detection compared to traditional manual methods.

Clinical Evidence

Performance established via comparative bench testing against a commercial IFA kit using 355 serum samples. Relative sensitivity 92.1% (95% CI: 86.3%-97.8%), relative specificity 98.0% (95% CI: 96.2%-99.8%), and relative agreement 96.5% (95% CI: 94.5%-98.5%). Precision studies (intra-assay, inter-assay, and inter-site) conducted across three sites; CVs generally <15% for positive samples. Reproducibility study across three sites showed 97.1% agreement with expected results. No clinical data from patients with documented Chlamydia infections was used.

Technological Characteristics

Enzyme-Linked Immunosorbent Assay (ELISA) using purified Chlamydia antigen (strain LGV II) coated on solid-phase microtiter wells. Detection via enzyme-labeled anti-human IgG conjugate and substrate-induced colorimetric reaction. Photometric measurement of optical density. Manual or semi-automated laboratory procedure. Precision guidance follows NCCLS EP5.

Indications for Use

Indicated for the qualitative detection of IgG antibodies to Chlamydia in human serum to determine immunological experience in individuals of various ages and genders.

Regulatory Classification

Identification

Chlamydia serological reagents are devices that consist of antigens and antisera used in serological tests to identify antibodies to chlamydia in serum. Additionally, some of these reagents consist of chlamydia antisera conjugated with a fluorescent dye used to identify chlamydia directly from clinical specimens or cultured isolates derived from clinical specimens. The identification aids in the diagnosis of disease caused by bacteria belonging to the genus Chlamydia and provides epidemiological information on these diseases. Chlamydia are the causative agents of psittacosis (a form of pneumonia), lymphogranuloma venereum (a venereal disease), and trachoma (a chronic disease of the eye and eyelid).

Predicate Devices

• IFA

Submission Summary (Full Text)

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K962558
Summary of Safety and Effectiveness Information Chlamydia IgG ELISA Test Kit
FEB 24 1997

I. Immuno Probe Inc.
1306 Bailes Lane, Suite F
Frederick, Maryland 21701
Contact person: William Boteler
Telephone: [phone]
Date of preparation: Jan 13, 1996

## II. Description of Device

The Chlamydia IgG ELISA kit is an Enzyme-Linked Immunosorbent Assay (ELISA) for qualitative detection of IgG antibodies in human serum to *Chlamydia* for the determination of immunological experience.

The Chlamydia IgG ELISA test is an enzyme linked immunosorbent assay to detect IgG antibodies to Chlamydia. Purified Chlamydia antigen (strain LGV II) is attached to a solid phase microtiter well. Diluted test sera is added to each well. If the antibodies are present that recognize the antigen, they will bind to the antigen in the well. After incubation the wells are washed to remove unbound antibody. An enzyme labeled anti-human IgG is added to each well. If antibody is present it will bind to the antibody attached to the antigen on the well. After incubation the wells are washed to remove unbound conjugate. A substrate solution is added to each well. If enzyme is present the substrate will undergo a color change. After an incubation period the reaction is stopped and the color intensity is measured photometrically, producing an indirect measurement of specific antibody in the patient specimen.

## III. Predicate Device

The Chlamydia IgG ELISA test is substantially equivalent to IFA. Equivalence is demonstrated by the following comparative results:

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# Performance Characteristics

1. Relative sensitivity and specificity. Two different sites compared the Wampole Chlamydia IgG ELISA test relative to a commercial IFA kit. The two sites were R&amp;D laboratories at commercial companies located in Maryland and New York and affiliated with the manufacturing of the kit. The sera were from normal individuals of various ages, gender, and geographical areas. The results of the studies are compiled and summarized in Table 1. None of the performance characteristics were established with specimens from patients having documented chlamydia infections.

Table 1
Comparison of Chlamydia IgG ELISA and IFA

| | Wampole Chlamydia IgG ELISA | | | |
| --- | --- | --- | --- | --- |
| | + | eq | - | Total |
| + >1:8 | 81 | 7 | 7 | 95 |
| Chlamydia IFA | | | | |
| - <1:8 | 5 | 9 | 246 | 260 |
| Total | 86 | 16 | 253 | 355 |

Relative Sensitivity = 81/88 = 92.1% 95% Confidence interval = 86.3% - 97.8%
Relative Specificity = 246/251 = 98.0% 95% Confidence interval = 96.2% - 99.8%
Relative Agreement = 327/339 = 96.5% 95% Confidence interval = 94.5% - 98.5%

Equivocals were not included in the above calculations.
The 95% confidence intervals were calculated using the normal method.

Please be advised that 'relative' refers to the comparison of this assay's results to that of a similar assay. There was not an attempt to correlate the assay's results with disease presence or absence. No judgment can be made on the comparison assay's accuracy to predict disease.

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2. Precision. Seven sera were assayed ten times each on three different assays at two different sites. Both sites were affiliated with the manufacturing of the kit. The inter and intra assay precision for each site is presented in Tables 2 and 3 and the intersite precision is shown in Table 4. With appropriate technique the user should obtain precision of &lt;15% CV.

Table 2 Chlamydia IgG ELISA Intra and Inter Assay Precision Study 1

| Assay(n=30) | Assay 1 (n=10) | | | Assay 2 (n=10) | | | Assay 3 (n=10) | | | Inter- | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | X | SD | CV | X | SD | CV | X | SD | CV | X | SD | CV |
| 1 | 2.86 | 0.152 | 5.32% | 2.97 | 0.076 | 2.57% | 3.13 | 0.115 | 3.69% | 2.99 | 0.162 | 5.42% |
| 2 | 1.71 | 0.101 | 5.91% | 1.88 | 0.098 | 5.20% | 1.90 | 0.092 | 4.89% | 1.83 | 0.129 | 7.05% |
| 3 | 1.74 | 0.107 | 6.15% | 1.87 | 0.071 | 3.78% | 1.95 | 0.072 | 3.67% | 1.85 | 0.121 | 6.50% |
| 4 | 1.78 | 0.126 | 7.07% | 1.92 | 0.053 | 2.77% | 2.03 | 0.075 | 3.72% | 1.91 | 0.135 | 7.06% |
| 5 | 1.06 | 0.051 | 4.83% | 1.12 | 0.034 | 3.00% | 1.16 | 0.049 | 4.24% | 1.11 | 0.060 | 5.42% |
| 6 | 0.34 | 0.032 | 9.59% | 0.32 | 0.042 | 13.06% | 0.37 | 0.052 | 14.25% | 0.34 | 0.046 | 13.55% |
| 7 | 0.30 | 0.061 | 19.95% | 0.29 | 0.056 | 19.43% | 0.33 | 0.043 | 12.81% | 0.31 | 0.054 | 17.75% |

Table 3 Chlamydia IgG ELISA Intra and Inter Assay Precision Study 2

| Sera# | Assay 1 (n=10) | | | Assay 2 (n=10) | | | Assay 3 (n=10) | | | Inter-Assay(n=30) | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | X | SD | CV | X | SD | CV | X | SD | CV | X | SD | CV |
| 1 | 3.08 | 0.052 | 1.69% | 3.11 | 0.106 | 3.40% | 3.00 | 0.117 | 3.91% | 3.06 | 0.104 | 3.41% |
| 2 | 1.77 | 0.085 | 4.80% | 1.78 | 0.073 | 4.10% | 1.75 | 0.094 | 5.38% | 1.77 | 0.084 | 4.75% |
| 3 | 1.86 | 0.062 | 3.35% | 1.85 | 0.086 | 4.63% | 1.86 | 0.083 | 4.46% | 1.86 | 0.076 | 4.08% |
| 4 | 1.81 | 0.060 | 3.30% | 1.84 | 0.112 | 6.12% | 1.84 | 0.102 | 5.52% | 1.83 | 0.091 | 4.98% |
| 5 | 0.93 | 0.051 | 5.46% | 0.93 | 0.071 | 7.69% | 0.94 | 0.053 | 5.61% | 0.93 | 0.058 | 6.19% |
| 6 | 0.04 | 0.014 | 31.17% | 0.03 | 0.018 | 53.59% | 0.06 | 0.024 | 39.50% | 0.05 | 0.022 | 46.90% |
| 7 | 0.05 | 0.016 | 35.60% | 0.05 | 0.015 | 32.60% | 0.07 | 0.032 | 47.62% | 0.05 | 0.024 | 45.41% |

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Table 4 Chlamydia IgG ELISA Inter Site Precision Study

| Inter-Site (n=60) | | | |
| --- | --- | --- | --- |
| Sera # | X | SD | CV |
| 1. | 3.03 | 0.140 | 4.63% |
| 2. | 1.80 | 0.112 | 6.24% |
| 3. | 1.86 | 0.100 | 5.37% |
| 4. | 1.87 | 0.121 | 6.46% |
| 5. | 1.02 | 0.110 | 10.73% |
| 6. | 0.19 | 0.153 | 78.91% |
| 7. | 0.18 | 0.137 | 75.20% |

X = Mean
SD = standard deviation
CV = coefficient of variation = SD/X x 100

Refer to NCCLS EP5 for guidance for appropriate precision determination.

3. CF Paired Serum Analysis. Nine serum pairs showing a greater than 4 fold increase in CF titer or seroconversions by CF were assayed on the Chlamydia IgG ELISA assay. Each serum pair was evaluated to determine an seroconversion in antibody (acute negative and convalescent positive). Four pairs demonstrated a seroconversion by ELISA. Therefore the assay showed a sensitivity of 44% (4/9) in demonstrating a seroconversion when the CF showed a 4 fold increase or a seroconversion.

4. Reproducibility Study. Fifty different sera with various levels of activity were assayed at three different sites. Two sites were R&amp;D laboratories at commercial companies located in Maryland and New York. The third site was a large clinical laboratory located in Pennsylvania. The data from the three sites show good correlation with ISR values with product moment correlation coefficients of &gt;0.989 between the sites. Excluding equivocals (n = 13) four determinations varied from its expected result (negative results for a positive specimen) giving a % agreement of expected results between the three sites of 97.1% (133/137). The expected results were derived from previous Wampole ELISA testing of the samples.