Several ELISA tests based on mycobacterial antigens have been used for the rapid diagnosis of tuberculosis (TB), although demonstration of Mycobacterium tuberculosis in a smear or culture is the most reliable method. In the present study, the diagnostic value of 16-kDa and 38-kDa mycobacterial antigens was investigated in patients who were diagnosed with tuberculosis by clinical and/or bacteriological findings in Turkey.The PATHOZYME-TB Complex Plus commercial ELISA kit was used for measuring immunoglobulin G against 38-kDa and 16-kDa recombinant antigens. Humoral immune response was analysed in a group of 179 TB patients (143 smear-positive, 19 smear-negative, eight lymphadenitis and nine pleuritis), 15 inactive TB cases and in control groups consisting of 40 healthy volunteers and 20 subjects with pulmonary diseases other than TB.The sensitivity, specifity, positive predictive value and negative predictive value of the test were determined at 52.5%, 93.3%, 95.9% and 39.7%, respectively in TB cases. Antibodies were detected at above cut-off level in three (20%) out of 15 subjects with inactive TB.In conclusion, the ELISA test has a very good specifity and an acceptable sensitivity and positive predictive value. It is thought that it could be used in combination with other methods to increase diagnostic accuracy, especially for culture-negative tuberculosis cases, which are difficult to diagnose.

Although the sensitivity and specificity of nucleic acid amplification assays are high with smear-positive samples, the sensitivity with smear-negative and extrapulmonary samples for the diagnosis of tuberculosis in suspicious tuberculosis cases still remains to be investigated. This study evaluates the performance of the GenoType Mycobacteria Direct (GTMD) test for rapid molecular detection and identification of the Mycobacterium tuberculosis complex and four clinically important nontuberculous mycobacteria (M. avium, M. intracellulare, M. kansasii, and M. malmoense) in smear-negative samples. A total of 1,570 samples (1,103 bronchial aspiration, 127 sputum, and 340 extrapulmonary samples) were analyzed. When we evaluated the performance criteria in combination with a positive culture result and/or the clinical outcome of the patients, the overall sensitivity, specificity, and positive and negative predictive values were found to be 62.4, 99.5, 95.9, and 93.9%, respectively, whereas they were 63.2, 99.4, 95.7, and 92.8%, respectively, for pulmonary samples and 52.9, 100, 100, and 97.6%, respectively, for extrapulmonary samples. Among the culture-positive samples which had Mycobacterium species detectable by the GTMD test, three samples were identified to be M. intracellulare and one sample was identified to be M. avium. However, five M. intracellulare samples and an M. kansasii sample could not be identified by the molecular test and were found to be negative. The GTMD test has been a reliable, practical, and easy tool for rapid diagnosis of smear-negative pulmonary and extrapulmonary tuberculosis so that effective precautions may be taken and appropriate treatment may be initiated. However, the low sensitivity level should be considered in the differentiation of suspected tuberculosis and some other clinical condition until the culture result is found to be negative and a true picture of the clinical outcome is obtained.Acid-fast smear examination and culture (liquid-and solidbased media, automated and semiautomated systems) are conventional techniques for microbiological detection of mycobacteria causing tuberculosis (TB) (14, 24). However, the sensitivity of smear has been variable (range, 20 to 80%) (1). In some smear-negative cases, TB might be difficult to differentiate from a number of other clinical pictures. Therefore, invasive medical procedures are necessary for sampling of patients from whom a qualified sputum sample cannot be obtained or in case of extrapulmonary TB, which requires histopathological, cytopathological, and microbiological examination of tissue specimens and body fluids. Nucleic acid amplification (NAA) techniques have been used for early detection of causative mycobacteria in clinical samples and also to support the clinical and radiological diagnosis in patients with presumptive Mycobacterium tuberculosis infection (3,19,33). Although the specificity values obtained with both smear-positive and smear-negative samples are high, the sensitivities of molecular assays are rather less w...

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While the value of the QFT-G test in exclusion of tuberculous pleurisy was found to be higher in this study, its other diagnostic efficiency values were detected to be low. It is recommended that a new cut-off value be established while diagnosing active TB in prospective clinical studies and that it is also essential to do the same for the studies in various regions with high and low prevalence of TB.

In this study, Mycobacterium tuberculosis complex was detected by BD ProbeTec ET system in 4716 respiratory and 167 nonrespiratory samples [mostly (98%) smear negative]. Sensitivity, specificity, positive and negative predictive values were 81.8%, 98.3, 85.1 and 97.9 for respiratory and 100%, 96.2, 64.7 and 100, for nonrespiratory samples, respectively. Among 149 (3.1%) ProbeTec DTB positive and culture negative samples, 72 (65 respiratory and seven nonrespiratory) (48.3%) were recovered from the patients who were evaluated as having TB infection. The system has been found as useful in early diagnosis of tuberculosis infection in association with the clinical, radiological and histopathological findings.