Antibody detection for the diagnosis of tuberculous pleuritis.

SETTING: University Hospital, Bangkok, Thailand. OBJECTIVE: To evaluate the diagnostic value of antibody detection in serum and in pleural effusion as a marker of tuberculous pleuritis (TBP). DESIGN: Cross-sectional study. MATERIALS AND METHODS: One hundred and fifty-five patients with pleural effusion who underwent diagnostic evaluation at Siriraj Hospital between March 1999 and May 2000 were recruited. Samples of pleural fluid were examined biochemically, cytologically and microbiologically. Pathological examination of pleural tissue was also performed. The diagnosis of TBP or other diagnosis was made by either pathological finding or culture result. Immunochromatographic tuberculosis (ICT-TB) tests for antibody detection were then performed using the stored serum samples and effusions from those patients with a final definite diagnosis. This test detects antibodies to five secreted antigens of Mycobacterium tuberculosis, including the 38 kDa antigen. RESULTS: We investigated 67 patients with TBP, 44 with malignant pleural effusions, seven with transudates and one with cryptococcal pleuritis. The combined ICT-TB serum and effusion tests were positive in 34/67 TBP and 22/52 non-TBP patients. The sensitivity, specificity, positive predictive value and negative predictive value of the ICT-TB test were 50.7, 57.7, 60.7 and 47.6%, respectively. In 11 TBP patients with human immunodeficiency virus (HIV) co-infection, the sensitivity of the ICT-TB test was 45.6%. There was no correlation between the test positivity and culture result or duration of disease. CONCLUSIONS: The diagnostic value of antibody detection in TBP is modest in an area with intermediate prevalence of tuberculosis, independently of HIV serological status.

Can serial qualitative polymerase chain reaction monitoring predict outcome of pulmonary tuberculosis treatment?

BACKGROUND: The aim of this study was to assess the use of qualitative one-tube nested polymerase chain reaction (PCR) for monitoring the treatment response in smear-positive pulmonary tuberculosis, and the factors determining the negative conversion of sputum smear, culture, and PCR during treatment. METHODOLOGY: A total of 53 patients receiving a standard short course of chemotherapy with 24 months follow-up period after treatment cessation were included in the study. Sputum specimens were collected serially for smear, culture, and PCR until the treatment was complete. RESULTS: The conversion rate for sputum culture, smear, and PCR at 8 weeks after treatment were 84.9, 58.5, and 47.1%, and at 16 weeks of treatment were 100, 88.7, and 79.2%, respectively. At the end of the treatment period, there were four PCR persisters, one of whom had disease relapse. Only cavitary disease had an influence over the negative conversion of the smear and PCR at 8 weeks (RR 3.5, 95% CI 1.04-11.95, P=0.04 for smear; RR 5.06, 95% CI 1.196-21.42, P=0.03 for PCR). CONCLUSION: Qualitative PCR was not useful for monitoring therapy in smear-positive pulmonary tuberculosis. Mycobacterium DNA was cleared slowly in cavitary disease. The PCR may be performed at the time of treatment cessation to identify those with potential for disease relapse.