External quality control of Mycobacterium tuberculosis drug susceptibility testing: results of two rounds in endemic countries.

SETTING: Quality assurance for the World Health Organization (WHO)/International Union Against Tuberculosis and Lung Disease (The Union) global tuberculosis (TB) drug resistance surveillance programme. OBJECTIVE: To monitor the quality of drug susceptibility testing (DST) in different countries. METHODS: In 2002-2003 and 2005-2006, 20 Mycobacterium tuberculosis strains were sent by the WHO/Union Supranational Reference Laboratory of Rome to TB reference laboratories in Albania, Bahrain, Kosovo, Mozambique, Oman, Qatar and Turkey for external quality control (EQC). RESULTS: In 2002-2003, the specificity, sensitivity, efficiency, reproducibility and predictive values for resistance/susceptibility were >or=90% for streptomycin (SM), isoniazid (INH) and ethambutol (EMB). In 2005-2006, all statistical values were >or=96% for SM, INH, rifampicin and EMB. CONCLUSION: EQC improved the quality of M. tuberculosis DST in the participating countries.

Detection of Mycobacterium tuberculosis DNA from peripheral blood in patients with HIV-seronegative and new cases of smear-positive pulmonary tuberculosis by polymerase chain reaction.

Tuberculosis is still one of the most important cause of mortality and morbidity in many countries and there is a need for new methods for accurate and rapid diagnosis of tuberculosis. To determine the sensitivity and specificity of polymerase chain reaction (PCR) method, we have evaluated Mycobacterium tuberculosis DNA in peripheral blood samples with PCR technique in adult patients with human immunodeficiency virus (HIV)-negative and new cases of smear-positive pulmonary tuberculosis. We investigated the relationship between characteristic of the patients, radiological extension of the disease, sputum smear grade, presence of cavity, body-mass index (BMI) serum albumin level, total delay time and PCR positivity. Forty patients (33 male and 7 female; mean age 37.8 +/- 14.1) and 20 healthy control subjects (13 male and 7 female; mean age 35.6 +/- 7.3) were enrolled in this study. PCR was positive in 16 of 40 (40%) patients with pulmonary tuberculosis and negative in 24 of 40 (60%). None of the healthy controls had positive PCR results. The overall sensitivity specificity and accuracy of the PCR assay was 40, 100 and 60%, respectively. We found the positive correlation between PCR positivity and sputum smear grade (r=0.46, P=0.003) radiological extension of the disease (r=0.69, P=0.001), presence of cavity (r=0.90, P=0.001). We conclude that the detection of M. tuberculosis DNA from peripheral blood by PCR technique is useful for the rapid diagnosis of tuberculosis patients with HIV-negative. Hematogenous dissemination was important in tuberculosis patients and peripheral blood samples were suitable and easy materials. However, standardization of the PCR method must be ensured for the diagnosis of tuberculosis.

The comparison of adenosine deaminase activity values with polymerase chain reaction results in patients with tuberculosis.

Three methods in the diagnosis and treatment of tuberculosis have been compared in this study. Serum adenosine deaminase activities of patients with tuberculosis was compared with those of control groups with (+) and (-) PPD (purified protein derivative) results and were found to be higher than the controls. Within the controls the PPD (+) group displayed higher adenosine deaminase activities in comparison to the PPD (-) group. All patients had growth of B. Tuberculosis in the culture medium and all but one had positive polymerase chain reaction (PCR) results. Control patients were negative for culture and PCR. The sensitivity of ADA (adenosine deaminase) assay was 91.7% and specificity was 94.5%, whereas PCR had a sensitivity of 95.8% and a specificity of 100%. The ADA assay may be used in adjunction with other methods in the follow-up of tuberculosis with high sensitivity, specificity, and ease in applicability and specimen collection.