IS-TOXOPLASMA IGG TEST SYSTEM

K981498 · Diamedix Corp. · LGD · Aug 21, 1998 · Microbiology

Device Facts

• Record ID: K981498
• Device Name: IS-TOXOPLASMA IGG TEST SYSTEM
• Applicant: Diamedix Corp.
• Product Code: LGD · Microbiology
• Decision Date: Aug 21, 1998
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.3780
• Device Class: Class 2

Intended Use

The Diamedix Is-Toxoplasma IgG Test Kit is an Enzyme Immunoassay (EIA) for the qualitative and quantitative determination of IgG antibodies in human serum to aid in the assessment of the patient's immunological response to infection with Toxoplasma gondii and in the determination of the immune status of individuals, including females of child-bearing age. The evaluation of acute and convalescent sera can aid in the diagnosis of primary or reactivated infection with Toxoplasma gondii. These reagents can be used either manually or in conjunction with the MAGO® Plus Automated EIA Processor. This product is not FDA cleared for use in screening blood and plasma donors.

Device Story

Is-Toxoplasma IgG Test System is an enzyme-linked immunosorbent assay (ELISA) for detecting IgG antibodies to Toxoplasma gondii in human serum. Partially purified T. gondii antigens are immobilized on microtiter wells; patient serum is added; if specific IgG is present, it binds to the antigen. After washing, enzyme-labeled anti-human immunoglobulin conjugate is added, followed by substrate. Color intensity is measured photometrically, providing an indirect quantitative measure of antibody concentration. The assay is performed manually or using the MAGO Plus Automated EIA Processor in clinical laboratory settings. Results are used by clinicians to assess immune status and aid in diagnosing primary or reactivated infections. The device benefits patients by providing diagnostic information regarding T. gondii exposure and infection status.

Clinical Evidence

Clinical performance evaluated across 621 serum samples at three sites. Comparison against other marketed EIAs showed relative sensitivities ranging from 87.5% to 93.3% and relative specificities from 98.7% to 100.0%. Overall agreement ranged from 92.1% to 99.4%. Discordant samples were resolved using a referee EIA method. Precision studies (intra-assay and inter-assay) were conducted across the reportable range. Linearity and correlation to the WHO 3rd International Standard for Anti-Toxoplasma Serum were demonstrated with R-squared values >0.99.

Technological Characteristics

Enzyme-linked immunosorbent assay (ELISA) using partially purified T. gondii antigens immobilized on microtiter wells. Employs enzyme-labeled anti-human immunoglobulin conjugate and substrate for photometric detection. Compatible with manual processing or MAGO Plus Automated EIA Processor. Quantitative results calibrated against WHO 3rd International Standard. Standard laboratory equipment required for photometry.

Indications for Use

Indicated for qualitative and quantitative detection of IgG antibodies to Toxoplasma gondii in human serum. Used to assess immunological response, determine immune status (including females of child-bearing age), and aid in diagnosis of primary or reactivated infection. Not for blood or plasma donor screening.

Regulatory Classification

Identification

Toxoplasma gondii serological reagents are devices that consist of antigens and antisera used in serological tests to identify antibodies to Toxoplasma gondii in serum. Additionally, some of these reagents consist of antisera conjugated with a fluorescent dye (immunofluorescent reagents) used to identify Toxoplasma gondii from clinical specimens. The identification aids in the diagnosis of toxoplasmosis caused by the parasitic protozoan Toxoplasma 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.

Predicate Devices

• Incstar Toxoplasma IgG ELISA Kit

Submission Summary (Full Text)

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## AUG 2 / 1998

K981498

## 510(k) Summary of Safety and Effectiveness

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.

The assigned 510(k) number is:

#### Applicant Information:

| Date Prepared: | April 24, 1998 |
|----------------|-----------------------------------------|
| Name: | Diamedix Corporation |
| Address: | 2140 N. Miami Avenue<br>Miami, FL 33127 |

| Contact Person: | Dr. Lynne Stirling |
|-----------------|--------------------|
| Phone Number: | 305-324-2354 |
| Fax Number: | 305-324-2585 |

#### Device Information:

| Trade Name: | Is-Toxoplasma IgG Test System |
|----------------------|---------------------------------------------------------------------------|
| Common Name: | <i>Toxoplasma gondii</i> EIA Test |
| Classification Name: | Enzyme linked immunosorbent assay, <i>Toxoplasma gondii</i><br>(866.3780) |

#### Equivalent Device:

Incstar Toxoplasma IgG ELISA Kit

Device Description: The Is-Toxoplasma IgG Test System is an enzyme-linked immunosorbent assay (ELISA) for the qualitative and quantitative detection of IgG to Toxoplasma gondii in human serum

Intended Use: The assay is intended for use in detecting IgG antibodies to T. gondii antigen in human serum. The results of the assay can be used as an aid in the assessment of the patient's immunological response to infection with T. gondii and in the determination of immune status of individuals, including females of child-bearing age. The evaluation of paired sera can aid in the diagnosis of primary or reactivated infection.

Principle of the Procedure: The Is-Toxoplasma IgG Test System is an enzyme-linked immunosorbent assay to detect IgG to Toxoplasma gondii in human serum. Partially purfied T. gondii antigens are attached to a solid phase microtiter well. Diluted test sera are added to each well. If antibodies which recognize the T. gondii antigens are present in the patient sample they will bind to the antigens on the well. After incubation, the wells are washed to remove unbound antibody. An enzyme labeled anti-human immunoglobulin (conjugate) is added to each test well. If antibody is present the enzyme-linked antibody will bind to it. After incubation, the wells are washed to remove unbound conjugate. A substrate solution is then added to each well. If enzyme is present from the prior step, the reaction is stopped and the color intensity is measured photometrically producing an indirect measure of the specific antibody present in the patient sample.

## 000246

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# SUMMARY OF SAFETY AND EFFECTIVENESS

# Performance Characteristics

#### A. Comparison Testing

A total of six hundred and twenty one sera were tested for the presence of toxoplasma IgG antibodies using the Diamedix Is-Toxoplasma IgG Test Kit and three other marketed tests at two independent sites (site #1, Miami, FL and site #2, Salt Lake City, Utah) as well as at Diamedix Corp., Miami, FL (site #3). At site #3 testing was performed both manually and using the MAGO Plus Automated EIA Processor.

Site #1 tested 200 samples (37% fresh and 73% frozen). Samples were obtained from the S. Florida area. Site #1 purposefully selected their sample population in order to provide an equal number of positive and negative results. Table 1 compares the results obtained for the Is-Toxoplasma IgG Test Kit and their currently used testing method.

Site #2 tested 179 samples (all fresh) submitted for ToRCH screening. Samples were obtained from the West region. Table 2 compares the results obtained for the Is-Toxoplasma IgG Test Kit and their currently used testing method.

#### TABLE 1

Is-Toxoplasma IgG - Site #1

Is-Toxoplasma IgG - Site #2

Equivocal 0

0

0

95% CI* 68.0 - 99.8

97.8 - 100.0

96.9 - 100.0

| | | Positive | Negative | Equivocal | | Positive | Negative | Equivocal |
|---------------|------------------------------------------------------------------------------------------------------------------|----------|----------|-----------|-----------|--------------------------------------------------------------------------------------------------------------------|----------|-----------|
| Other<br>EIAs | Positive | 98 [23] | 14 [4] | 3 | Positive | 14 [6] | 1 | |
| | Negative | 1 | 77 [29] | 0 | Negative | 0 | 164 [65] | |
| | Equivocal | 0 | 6 | 1 | Equivocal | 0 | 0 | |
| | Relative Sensitivity 98/112 = 87.5%<br>Relative Specificity 77/78 = 98.7%<br>Overall Agreement** 175/190 = 92.1% | | | | | Relative Sensitivity 14/15 = 93.3%<br>Relative Specificity 164/164 = 100.0%<br>Overall Agreement** 178/179 = 99.4% | | |
| | 95% CI*<br>81.4 - 93.6<br>93.1 - 100.0<br>87.3 - 95.5 | | | | | | | |

For Site #1, further resolution of the discordant samples was performed by testing such samples in a referee EIA method. Twelve of the samples negative by the Is-Toxoplasma IgG Test Kit and positive by the other EIA were negative by the referee method; the remaining two sera were equivocal. The sample that was positive in the Is-Toxoplasma IgG Test Kit and negative in the other EIA was negative when tested by the referee method.

For Site #2, further resolution of the discordant sample was performed in a similar manner. The sample that was negative in the Is-Toxoplasma IgG Test Kit and positive by the other EIA was negative in the referee EIA method.

Site #3 (Diamedix Corp.) tested 242 samples (all frozen) by the manual method and 241 of these samples (one being QNS) by the MAGO Plus method. Samples were obtained from S. Florida blood donors. Tables 3 and 4 compare the results obtained for the Is-Toxoplasma IgG Test Kit and another marketed EIA method.

| TABLE 3<br><i>Is-Toxoplasma IgG</i> - Site #3 : Manual | | | | | TABLE 4<br><i>Is-Toxoplasma IgG</i> - Site #3 : MAGO Plus | | | |
|--------------------------------------------------------|----------------------|-----------------|----------|----------------------|-----------------------------------------------------------|--------------------------------------|----------|----------------------|
| | | Positive | Negative | Equivocal | | Positive | Negative | Equivocal |
| Other<br>EIA | Positive | 47 [16] | 5 | 2 | Positive | 49 | 4 | 1 |
| | Negative | 1 | 186 [73] | 0 | Negative | 1 | 185 | 0 |
| | Equivocal | 0 | 1 | 0 | Equivocal | 0 | 1 | 0 |
| | Relative Sensitivity | 47/52 = 92.2% | | 95% CI*<br>81.5-97.9 | | Relative Sensitivity 49/53 = 92.5% | | 95% CI*<br>81.8-97.9 |
| | Relative Specificity | 186/187 = 99.5% | | 97.1-100.0 | | Relative Specificity 185/186 = 99.5% | | 97.0-100.0 |
| | Overall Agreement** | 233/239 = 97.5% | | 94.6-99.1 | | Overall Agreement** 234/239 = 97.9 % | | 95.2-99.3 |

[ ] denotes samples from females of child-bearing age.

* 95% Confidence Intervals (CI) calculated by the Exact Method.

** Equivocal results were excluded from calculations

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For Site #3 (manual testing), further resolution of the discordant sera revealed that the 5 sera negative in the Is-Toxoplasma IgG Test Kit but positive in the other EIA were also negative by a referee EIA method. The serum that was positive in the Is-Toxoplasma IgG Test Kit and negative in the other EIA was positive by the referee method. For MAGO Plus testing, the 4 sera that were negative in the Is-Toxoplasma IgG Test Kit but positive in the other EIA were also negative by a referee EIA method. The serum that was positive in the Is-Toxoplasma IgG Test Kit and negative in the other EIA was positive by the referee method.

NOTE : Please be advised that 'relative' refers to the comparison of the 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 comparison assay's accuracy to predict disease.

## B. Correlation of Manual and MAGO Plus Results

The Is-Toxoplasma IgG Test Kit has been developed for automated as well as manual use. To demonstrate the equivalence of the manual and MAGO Plus Procedures, the results of 211 serum samples tested in the comparison studies were plotted. Thirty highly reactive samples exceeded the reportable range and were excluded from this comparison. A scattergram and regression line of the results obtained with 95% confidence intervals is shown in Figure 1.

Image /page/2/Figure/4 description: The image is a scatter plot titled "FIGURE 1: Manual vs MAGO Plus Correlation". The x-axis is labeled "MANUAL IU/ML" and ranges from 0 to 250. The y-axis is labeled "MAGO PLUS IU/ML" and ranges from -50 to 300. The plot shows a positive correlation between the two variables, with the equation of the regression line being Y = 1.4991 + 1.0769 X and r = 0.9631.

## C. Linearity

Several strongly positive serum samples were serially dilutions were assayed, in duplicate, in the Is-Toxoplasma IgG Test Kit both manually and using the MAGO Plus Automated EIA Processor. Representative linear regression graphs and scattergrams of the mean results with 95% confidence intervals are presented in Figures 2 and 3 for one patient sample. The results demonstrate a high degree of linearity throughout the reportable range of the assay when samples are tested either manually or by MAGO Plus.

Image /page/2/Figure/7 description: The image contains two line graphs, the first titled "FIGURE 2: Manual Linearity" and the second titled "FIGURE 3: MAGO Plus Linearity". The first graph has a slope of 993.54, a y-intercept of -7.89, and an R-squared value of 0.9969. The second graph has a slope of 865.69, a y-intercept of -6.71, and an R-squared value of 0.9973.

## 000248

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### D. Correlation to WHO Standard

The Is-Toxoplasma IgG Test Kit has been calibrated against the WHO 3rd International Standard for Anti-Toxoplasma Serum (code TOXM). To demonstrate the accuracy of the quantitative procedure, several dilutions of the WHO Standard were prepared and assayed manually in triplicate in two different runs on two different days versus the Is-Toxoplasma IgG Test Kit standard curve. The linear regression graph and scattergram of the mean results with 95% Confidence Intervals is shown in Figure 4.

FIGURE 4 : Dilutions of WHO Standard

Image /page/3/Figure/2 description: The image is a graph titled 'assayed against Is-Toxoplasma IgG Standards'. The x-axis is labeled 'WHO IU/ML' and ranges from 0 to 250. The y-axis is labeled 'Is-Toxoplasma IU/ml' and ranges from 0 to 350. The graph shows a linear relationship with the equation Y = 4.3333 + 1.1946 X and an R-squared value of 0.9932.

## E. Quantitative Data

Serum pairs were obtained by preparing multiple two-fold dilutions of several strongly positive sera. Ratios for dilutions representing a four-fold difference in antibody level were evaluated as a serum pair both manually and using the MAGO Plus. Overall, it was estimated that a 3.9 to 6.2 fold (mean 5.1 fold ) increase in Is-Toxoplasma IgG IU/ml values corresponded to a four-fold titer increase in Toxoplasma IgG antibody levels.

## F. Cross Reactivity

Sera containing IgG antibodies to viruses potentially cross-reactive to T. gondit have been tested in the Is-Toxoplasma IgG Test Kit. Fifty sera negative for IgG antibodies to 7. gondii in the Is-Toxoplasma IgG Test Kit as well as in another marketed test but positive for one or more vinuses were evaluated. In additon, nine of these sera were positive for antinuclear antibodies (ANA) and two were positive for anti-DNA. The data in the following table suggest that no crossreactivity should be expected with the Is-Toxoplasma IgG Test Kit from these analytes.

| Analyte | Toxoplasma IgG | VZV IgG | HSV IgG | CMV IgG | Rubella IgG | EBV IgG | anti-DNA | ANA |
|--------------------|----------------|---------|---------|---------|-------------|---------|----------|-----|
| No.of Pos. Samples | 0 | 48 | 47 | 37 | 49 | 48 | 2 | 9 |

TABLE 5

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## G. Precision

Six serum samples, spanning the reportable range, as well as the 50 IU/ml kit Standard and kit Low Positive and Negative Ontrols were tested quantitatively and values calculated from IU/ml results. Sites #1 and #2 tested samples in triplicate in three separate runs on three different days. Site #3 (Diamedix Corp.) tested samples in triplicate in two separate runs on three different days both manually and using the MAGO Plus Automated EIA Processor. The results obtained are shown in Tables 6-9.

| SERUM | INTRA-ASSAY DAY 1 | | | INTRA-ASSAY DAY 2 | | | INTRA-ASSAY DAY 3 | | | INTERASSAY (n=9) | | |
|--------|-------------------|-------|-------|-------------------|-------|-------|-------------------|-------|-------|------------------|-------|-------|
| | MEAN IU/ml | SD | CV% | MEAN IU/ml | SD | CV% | MEAN IU/ml | SD | CV% | MEAN IU/ml | SD | CV% |
| A | 7.9 | 1.35 | 17.09 | 8.2 | 2.05 | 25.00 | 7.9 | 2.36 | 29.87 | 8.0 | 1.71 | 21.38 |
| B | 31.3 | 1.40 | 4.47 | 30.7 | 1.46 | 4.76 | 26.2 | 2.90 | 11.07 | 29.4 | 3.00 | 10.20 |
| C | 159.7 | 4.51 | 2.82 | 173.6 | 5.21 | 3.00 | 147.2 | 7.01 | 4.76 | 160.2 | 12.45 | 7.77 |
| D | 170.8 | 13.32 | 7.80 | 177.4 | 14.38 | 8.11 | 165.4 | 29.49 | 17.83 | 171.2 | 18.45 | 10.78 |
| E | 274.7 | 28.55 | 10.39 | 259.1 | 23.31 | 9.00 | 257.1 | 14.66 | 5.70 | 263.6 | 21.52 | 8.16 |
| F | 83.1 | 10.28 | 12.37 | 89.6 | 12.94 | 14.44 | 81.1 | 19.90 | 24.54 | 84.6 | 13.50 | 15.96 |
| 50 STD | 54.6 | 4.46 | 8.17 | 54.9 | 5.60 | 10.20 | 53.5 | 8.35 | 15.61 | 54.3 | 5.53 | 10.18 |
| LPC | 128.1 | 1.56 | 1.22 | 138.1 | 3.15 | 2.28 | 146.4 | 18.42 | 12.58 | 137.7 | 12.16 | 8.83 |
| NC | 13.2 | 0.40 | 3.03 | 12.9 | 0.51 | 3.95 | 15.7 | 1.65 | 10.51 | 13.9 | 1.58 | 11.37 |

TABLE 6 : Site #1 - Intra-Assay and Interassay Precision

TABLE 7 : Site #2 - Intra-Assay and Interassay Precision

| SERUM | INTRA-ASSAY DAY 1 | | | INTRA-ASSAY DAY 2 | | | INTRA-ASSAY DAY 3 | | | INTERASSAY (n=9) | | |
|--------|-------------------|-------|-------|-------------------|-------|-------|-------------------|-------|--------|------------------|-------|-------|
| | MEAN<br>IU/ml | SD | CV% | MEAN<br>IU/ml | SD | CV% | MEAN<br>IU/ml | SD | CV% | MEAN<br>IU/ml | SD | CV% |
| A | 10.1 | 1.46 | 14.46 | 5.4 | 1.03 | 19.07 | 1.1 | 1.47 | 133.60 | 5.5 | 4.07 | 74.00 |
| B | 25.9 | 3.56 | 13.75 | 25.0 | 2.79 | 11.16 | 21.0 | 1.15 | 5.48 | 24.0 | 3.25 | 13.54 |
| C | 145.1 | 8.32 | 5.73 | 136.3 | 5.15 | 3.78 | 70.3 | 4.79 | 6.81 | 117.2 | 35.83 | 30.57 |
| D | 162.8 | 8.92 | 5.48 | 132.9 | 3.70 | 2.78 | 95.1 | 2.96 | 3.11 | 130.3 | 29.81 | 22.88 |
| E | 250.0 | 0.00 | 0.00 | 237.9 | 9.96 | 4.19 | 189.2 | 8.92 | 4.71 | 225.7 | 28.68 | 12.71 |
| F | 56.8 | 6.61 | 11.64 | 75.5 | 2.76 | 3.66 | 31.0 | 3.80 | 12.26 | 54.5 | 19.77 | 36.28 |
| 50 STD | 48.7 | 6.57 | 13.49 | 51.7 | 3.79 | 7.33 | 41.8 | 0.76 | 1.82 | 47.4 | 5.82 | 12.28 |
| LPC | 134.9 | 19.60 | 14.53 | 123.1 | 11.22 | 9.11 | 123.1 | 11.22 | 9.11 | 127.0 | 13.92 | 10.96 |
| NC | 11.8 | 1.68 | 14.24 | 11.5 | 1.93 | 16.78 | 11.5 | 1.93 | 16.78 | 11.6 | 1.61 | 13.88 |

TABLE 8 : Site #3-Intra-Assay and Interassay Precision (Manual)

| SERUM | INTRA-ASSAY DAY 1 | | | INTRA-ASSAY DAY 2 | | | INTRA-ASSAY DAY 3 | | | INTERASSAY (n=18) | | |
|--------|-------------------|-------|-------|-------------------|-------|-------|-------------------|-------|-------|-------------------|-------|-------|
| | MEAN<br>IU/ml | SD | CV% | MEAN<br>IU/ml | SD | CV% | MEAN<br>IU/ml | SD | CV% | MEAN<br>IU/ml | SD | CV% |
| A | 2.6 | 1.51 | 58.08 | 1.9 | 0.44 | 23.16 | 2.4 | 0.70 | 29.17 | 2.3 | 0.98 | 42.61 |
| B | 17.4 | 2.08 | 11.95 | 19.3 | 2.28 | 11.81 | 19.2 | 1.41 | 7.34 | 18.7 | 2.04 | 10.91 |
| C | 115.3 | 8.59 | 7.45 | 105.6 | 9.88 | 9.36 | 105.6 | 22.04 | 20.87 | 108.8 | 14.69 | 13.50 |
| D | 141.6 | 5.54 | 3.91 | 141.6 | 6.90 | 4.87 | 137.7 | 10.86 | 7.89 | 140.3 | 7.82 | 5.57 |
| E | 238.7 | 20.56 | 8.61 | 246.8 | 16.69 | 6.76 | 240.7 | 19.48 | 8.09 | 242.1 | 18.17 | 7.51 |
| F | 55.1 | 5.21 | 9.46 | 46.3 | 1.62 | 3.50 | 58.0 | 8.22 | 14.17 | 53.3 | 7.32 | 13.73 |
| 50 STD | 56.7 | 8.12 | 14.32 | 55.4 | 8.99 | 16.23 | 57.3 | 3.53 | 6.16 | 56.5 | 6.89 | 12.19 |
| LPC | 138.8 | 10.99 | 7.92 | 139.0 | 8.07 | 5.81 | 148.6 | 8.29 | 5.58 | 142.1 | 9.87 | 6.95 |
| NC | 14.1 | 0.96 | 6.81 | 12.9 | 1.21 | 9.38 | 15.4 | 2.09 | 13.57 | 14.1 | 1.76 | 12.48 |

TABLE 9 : Site #3- Intra-assay and Interassay Precision (MAGO Plus)

| SERUM | | INTRA-ASSAY DAY 1 | | | | INTRA-ASSAY DAY 2 | | | | INTRA-ASSAY DAY 3 | | | | INTERASSAY (n=18) | | | |
|--------|------------|-------------------|-------|------------|-------|-------------------|------------|-------|-------|-------------------|-------|-------|--|-------------------|--|--|--|
| | MEAN IU/ml | SD | CV% | MEAN IU/ml | SD | CV% | MEAN IU/ml | SD | CV% | MEAN IU/ml | SD | CV% | | | | | |
| A | 2.0 | 1.54 | 77.00 | 2.0 | 2.60 | 130.00 | 3.9 | 1.89 | 48.46 | 2.6 | 2.15 | 82.69 | | | | | |
| B | 17.9 | 2.34 | 13.07 | 12.3 | 8.70 | 70.73 | 20.3 | 6.22 | 30.64 | 16.8 | 6.87 | 40.89 | | | | | |
| C | 150.0 | 5.99 | 3.99 | 154.3 | 5.07 | 3.29 | 156.6 | 20.31 | 12.97 | 153.6 | 12.14 | 7.90 | | | | | |
| D | 149.5 | 20.43 | 13.67 | 163.8 | 19.35 | 11.81 | 181.6 | 16.15 | 8.89 | 165.0 | 22.19 | 13.45 | | | | | |
| E | >250 | N/A | N/A | >250 | N/A | N/A | >250 | N/A | N/A | >250 | N/A | N/A | | | | | |
| G | 40.9 | 1.95 | 4.77 | 40.4 | 2.42 | 5.99 | 41.8 | 2.65 | 6.34 | 41.0 | 2.30 | 5.61 | | | | | |
| 50 STD | 65.7 | 4.24 | 6.45 | 79.2 | 10.45 | 13.19 | 78.4 | 9.35 | 11.93 | 74.4 | 10.19 | 13.70 | | | | | |
| LPC | 170.9 | 11.34 | 6.64 | 195.8 | 8.83 | 4.51 | 208.8 | 15.98 | 7.65 | 191.8 | 19.94 | 10.40 | | | | | |
| NC | 15.8 | 2.18 | 13.80 | 15.1 | 4.82 | 31.92 | 24.8 | 3.52 | 14.19 | 18.5 | 5.70 | 30.81 | | | | | |

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# Expected Values

The prevalence of Toxoplasma IgG antibodies in the normal population can vary depending on a number of factors such as age, geographical location, socio-economic status, race and type of test used. It has been esttimated that in the United States 8-20% of the normal population has anti-toxoplasma IgG antibodies ( 1). For finales of child-bearing age and for pregnant females prevalence rates from 16 to 50% have been reported (3).

In the present studies sera from 100 healthy South Florida donors (52 female and 48 male) were evaluated in the Is-Toxoplasma IgG Test Kit. Of the 100 samples, 22 (22%) were found to be positive and 78 (78%) were negative. Age distribution, geographic location and prevalence is provided in Table 10. Histograms demonstrating the distribution of IU/ml values are shown in Figures 5 and 6.

Thirty-seven of the female donors were of child-bearing age (18-45 years). Of the sera from these donors, 2 (5%) were positive and 35 (95%) were negative. A total of 45 sera from pregnant females (15 from each trimester) were also tested in the Is-Toxoplasma IgG Test Kit. Nine (20%) were positive and 36 (80%) were negative for anti-toxoplasma IgG. In addition, a total of 216 samples from females of childbearing age were identified in the outside and in-house clinical studies (these included the 45 sera from pregnant females already referenced). Of these samples, 45 (21%) were positive and 171 (79%) were negative for anti-toxoplasma IgG when evaluated in the Is-Toxoplasma IgG Test Kit.

| | Number of donors | Prevalence |
|----------------------------------------------|------------------|------------|
| Total Number | 100 | 22% |
| Geographic<br>location :<br>South Eastern US | 100 | 22% |
| Age | | |
| 10-19 | 13 | 15.4% |
| 20-29 | 23 | 17.4% |
| 30-39 | 40 | 17.5% |
| 40-49 | 13 | 15.4% |
| 50-59 | 5 | 40.0% |
| 60-69 | 6 | 83.0% |

TABLE 10

Image /page/5/Figure/6 description: The image contains two bar charts, labeled as "FIGURE 5" and "FIGURE 6", which display the frequency of Is-Toxoplasma IgG positive and negative populations, respectively. In Figure 5, the x-axis represents IU/mL values, and the y-axis represents frequency, with the >250 IU/mL category having the highest frequency at approximately 14. In Figure 6, the x-axis also represents IU/mL values, and the y-axis represents frequency, with the 0-10 IU/mL category having the highest frequency at approximately 75.

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Image /page/6/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo is circular, with the text "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" arranged around the perimeter. In the center of the circle is an abstract symbol that resembles an eagle or bird in flight, composed of three curved lines.

Food and Drug Administration 2098 Gaither Road Rockville MD 20850

## AUG 21 1998

Lynne Stirling, Ph.D. Vice President, Regulatory Affairs Diamedix Corporation 2140 N. Miami Ave. Miami. FL 33127

Re: K981498

Trade Name: Is-Toxoplasma IgG Test System Regulatory Class: II Product Code: LGD Dated: June 23, 1998 Received: June 25, 1998

Dear Dr. Stirling:

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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#### Page 2

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 [phone].

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 [phone]. Additionally, for questions on the promotion and advertising of your device, please contact the Office of Compliance at [phone]. 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 [phone] or at [phone] or at its internet address "http://www.fda.gov/cdrh/dsmamain.html"

Sincerely yours.

Steven Sutman

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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## Appendix G. Indications for Use Statement

## INDICATIONS FOR USE STATEMENT

# 510(K) NUMBER : _ K 98 14 98

## DEVICE NAME : Is-Toxoplasma IgG Test System

Indications for Use : The Diamedix Is-Toxoplasma IgG Test Kit is an Enzyme Immunoassay (EIA) for the qualitative and quantitative determination of IgG antibodies in human serum to aid in the assessment of the patient's immunological response to infection with Toxoplasma gondii and in the determination of the immune status of individuals, including females of child-bearing age. The evaluation of acute and convalescent sera can aid in the diagnosis of primary or reactivated infection with Toxoplasma gondii. These reagents can be used either manually or in conjunction with the MAGO® Plus Automated EIA Processor. This product is not FDA cleared for use in screening blood and plasma donors.

Woody Dubois

510(k) Number

000253