J Clin Pathol Qual Control.  1999 Jun;21(1):251-258.

The Evaluation of Enzyme Immunoassay for Diagnosis of Tuberculosis

• Kim EY
• Nahm CH
• Cho BW
• Kim EK
• Lee JW
• Pai SH

Abstract

BACKGROUND: Diagnosis of tuberculosis is usually established by acid fast stain and culture. To establish diagnosis of tuberculosis rapidly, polymerase chain reaction (PCR) has been introduced. However, this is tedious and expensive. We evaluated an enzyme immunoassay (EIA) technique using H(37)R(A) and recombinant 38 kDa antigens and compared this technique with other diagnostic modalities.
METHODS
We studied the presence or absence of IgG antibodies to Mycobacterium in human serum from 60 patients for whom the stain and culture for tuberculosis were requested and 20 healthy volunteers. The EIA was performed using commercially available kits for detection of IgG antibodies to Mycobacterium species (Pathozyme-Myco, Omega, Scotland, UK) and Mycobacterium tuberculosis complex (Pathozyme-TB complex, Omega, Scotland, UK). We used two different cut-off points : A. manufacturer recommended average low positive control optical density (OD) / 1.5 and B. average OD of healthy controls + 3SD. These results were compared with those of acid fast stain, culture, PCR, clinical, and radiological findings.
RESULTS
The concordance rates with other tests by using cut off point B were superior to those by cut off point A. According to cut off point B, the concordance rates of Pathozyme-Myco kit with acid fast stain, culture, and PCR were 68.3%, 63.3%, and 74.3%, respectively, and the concordance rates of Pathozyme-TB complex kit were 71.7%, 66.7%, and 80.0%, respectively. Forty percent of positive and 17.1% of negative result patients had past tuberculosis history.
CONCLUSIONS
There was 63.3% to 80.0% agreement between EIA method and various other existing methods. Six (50%) out of 12 patients who were positive by EIA but negative by other methods were considered having tuberculosis by clinical and radiological examinations. The advantage of EIA for the detection of IgG antibodies to Mycobacterium in human serum is easy to collect samples and rapid to perform many samples simultaneously. Thus, the EIA method could be a useful supplementary test in establishing diagnosis of tuberculosis among certain patients. Techniques specifically designed to detect of IgM antibodies against tuberculosis may be more useful for this purpose.

MeSH Terms

Antibodies
Diagnosis*
Healthy Volunteers
Humans
Immunoenzyme Techniques*
Immunoglobulin G
Immunoglobulin M
Mycobacterium
Mycobacterium tuberculosis
Polymerase Chain Reaction
Scotland
Tuberculosis*
Antibodies
Immunoglobulin G
Immunoglobulin M