How Reliable is Sputum PCR Test in the Diagnosis of Pulmonary Tuberculosis When Sputum Smear is Negative? / 결핵

BACKGROUND: Recent technological developments have introduced a new method to identifying M. tuberculosis complex DNA in clinical samples directly. The direct amplification test (DAT) is approved for identifying M. tuberculosis complex in respiratory specimens that are smear-positive for acid-fast bacilli (AFB). When there is a discrepancy between the AFB smear and DAT, no information on their clinical utility is currently available. In this study, the diagnostic reliability of DAT was investigated in suspected pulmonary tuberculosis patients whose sputum AFB smear was negative. METHODS: From June 1, 1998 through May 30, 1999, 909 patients with presumed active pulmonary tuberculosis were enrolled. A sputum AFB stain, culture, DAT and /or biopsy were performed. using the criteria of clinical tuberculosis or confirmed tuberculosis, the positive predictive value of DAT in diagnosing pulmonary tuberculosis was investigated. RESULTS: The positive predictive value of DAT was 82.1% by the clinically active tuberculosis criteria. However, it decreased to 61.5% when diagnosis was restricted to only to culture positive or biopsy proven cases. The false positive rate of DAT was 18.0%. CONCLUSION: The DAT is a valuable diagnostic method in suspected patients whose sputum AFB is was negative.

Clinical Usefulness of Various Methods for the Diagnosis of Tuberculosis / 대한임상병리학회지

BACKGROUND: In the diagnosis of tuberculosis, methods that have high sensitivity and specificity such as polymerase chain reaction and serologic test of tuberculosis have been introduced recently. Thus, we performed AFB stain, culture, PCR-ybridization and serologic test of tuberculosis to determine the clinical usefulness of each method in patients who were diagnosed as having pulmonary and extrapulmonary tuberculosis. METHODS: With the study subjects of 72 patients (57 with pulmonary tuberculosis, 15 with extrapulmonary tuberculosis) and controls of 60 persons, we performed the AFB stain, culture, PCR-ybridization and serologic test using an ICT(R) tuberculosis kit (AMRAD, Australia). Then, we compared diagnostic results in each tests and the effect of multiple tests among various methods. RESULTS: In 57 pulmonary tuberculosis patients, 42 (73.7%) showed positive with AFB stain, 40 (70.2%) with culture, 53 (93.0%) with PCR-ybridization, 47 (82.5%) with serologic test. And in 15 extrapulmonary tuberculosis patients, 4 showed positive (26.7%) with AFB stain, 5 (33.3%) with culture, 7 (46.7%) with PCR-ybridization method, and 12 (80.0%) with serologic test. In 72 tuberculosis patients, 67 (93.1%) showed positive for any of more than 2 tests among the 4 testing methods; and among 3 testing methods combined in different ways, 53 (73.6%) to 60 (83.3%) showed positive of any of more than 2 tests. CONCLUSIONS: We think that using the traditional method of detecting bacteria together with PCR-ybridization or serologic test would be a fast and accurate method of diagnosing tuberculosis. Especially, in those cases with extrapulmonary tuberculosis or taking a specimen of sputum is difficult, we think that serologic test would help in the diagnosis.

Clinical Usefulness of Various Methods for the Diagnosis of Tuberculosis / 대한임상병리학회지

BACKGROUND: In the diagnosis of tuberculosis, methods that have high sensitivity and specificity such as polymerase chain reaction and serologic test of tuberculosis have been introduced recently. Thus, we performed AFB stain, culture, PCR-ybridization and serologic test of tuberculosis to determine the clinical usefulness of each method in patients who were diagnosed as having pulmonary and extrapulmonary tuberculosis. METHODS: With the study subjects of 72 patients (57 with pulmonary tuberculosis, 15 with extrapulmonary tuberculosis) and controls of 60 persons, we performed the AFB stain, culture, PCR-ybridization and serologic test using an ICT(R) tuberculosis kit (AMRAD, Australia). Then, we compared diagnostic results in each tests and the effect of multiple tests among various methods. RESULTS: In 57 pulmonary tuberculosis patients, 42 (73.7%) showed positive with AFB stain, 40 (70.2%) with culture, 53 (93.0%) with PCR-ybridization, 47 (82.5%) with serologic test. And in 15 extrapulmonary tuberculosis patients, 4 showed positive (26.7%) with AFB stain, 5 (33.3%) with culture, 7 (46.7%) with PCR-ybridization method, and 12 (80.0%) with serologic test. In 72 tuberculosis patients, 67 (93.1%) showed positive for any of more than 2 tests among the 4 testing methods; and among 3 testing methods combined in different ways, 53 (73.6%) to 60 (83.3%) showed positive of any of more than 2 tests. CONCLUSIONS: We think that using the traditional method of detecting bacteria together with PCR-ybridization or serologic test would be a fast and accurate method of diagnosing tuberculosis. Especially, in those cases with extrapulmonary tuberculosis or taking a specimen of sputum is difficult, we think that serologic test would help in the diagnosis.

Evaluation of Enzyme Immunoassay for the Diagnosis of pulmonary Tuberculosis / 대한임상미생물학회지

BACKGROUND: The diagnosis of tuberculosis has been based on the detection of tubercle bacilli by acid-fast stain of smear or cultures, and recently the serologic diagnosis of tuberculosis has been provided a means of sensitive and specific detection of Mycobacterium tuberculosis. We evaluated the utility of enzyme immunoassay using determiner Tuberculosis Glicolipids(TBGL) antibody kit(Kyowa Medex Co. Ltd, Japan) to detect anti-TBGL antibody for diagnosis of pulmonary tuberculosis. METHODS: Anti-TBGL antibody assay was performed to the form 44 patients with active pulmonary tuberculosis(17 patients with smear positive, 7 patients with only culture positive, 20 patients with clinically active tuberculosis) and 80 controls (30 healthy controls, 24 patients with non-tuberculous respiratory diseases, 26 patients with inactive tuberculosis). We compared the sensitivity and specificity of anti-TBGL antibody with culture and AFB stain. RESULTS: Anti-TBGL antibodies were detected in 16 of 17(94%) smear positive patients, 4 of 7 patients with only culture positive and 16 of 20(80%) smear negative patients who had been clinically diagnosed as active pulmonary tuberculosis. Nine(35%) out of 26 patients with inactive tuberculosis, one(4%) out of 24 patients with non-tuberculous respiratory diseases and no one of healthy control had a positive antibody response. Overall sensitivity, specificity of the anti-TBGL antibody assay were 82%, 88%, respectively and sensitivities and specificities of culture and AFB smear 64%, 97%, and 49%, 100%, respectively. Anti-TBGL antibody titers in patients with active tuberculosis were significantly higher than control grup(P<0.05). Conclusions : The anti-TBGL antibody assay was sensitive, rapid and convenient. This assay will be useful as a tool for the diagnosis of tuberculosis in combination with other conventional methods.