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Tuberculosis (TB) caused by Mycobacterium tuberculosis has been identified as a remerging infectious disease with public health importance globally. Exploitation of better diagnosis techniques for precise isolation of mycobacteria in clinical specimens is of great importance to improve the diagnosis as part of the global TB control efforts. Contamination of broth cultures of acid-fast bacilli (AFB) by bacterial species other than Mycobacterium species frequently occurs. Many of these contaminated cultures require re-decontamination and re-incubation before the appropriate tests can be performed for identification. This study aimed at the isolation/recovery of M. tuberculosis from contaminated MGIT tubes by making minor modification to the standard protocol and access whether the modification has any impact on recovery rate. Among all confirmed 451 mixed growth positive cultures, 89.57% were culture positive (positive for MTBC), 3.80% were culture negative, 4.65% were culture contaminated and 1.99% were found NTM.

Establishing the definite causative etiology of pleural effusion is often quite problematic due to the paucibacillary nature of mycobacterium, while malignancy and other bacterial infections also cause pleural effusion. Therefore, knowing the exact cause is mandatory before the start of any anti tuberculosis therapy. The present study was aimed to differentiate among different causes of pleural effusion in suspected TB patients. Study Design: Cross sectional study. Setting: A cross sectional study was carried out at Gulab Devi Chest Hospital over the period of seven months. Total 32 patients were enrolled in the study following the inclusion criteria and after taking written informed consent from the patients and approval from the ethical committee. Period: From 1st September 2014 to 31st March 2015. Materials and Methods: Pleural effusion was aspirated by the registered clinician and the sample was processed for cytology, relative density, culture and PCR. Results: Total of ~10% patients were found positive for bacteria other than MTB and 25% were positive for MTB as evidenced by the growth on culture. Two of the MTB culture positive samples were positive for MTB DNA whereas, one culture negative sample was found positive by PCR. Our findings showed that no patient sample was test positive by AFB smearing which is the most commonly used diagnostic tool for MTB. MTB is the major cause of pleural effusion in our studied population but other bacterial infections cannot be neglected. Moreover, PCR is more robust method of detection as MTB culture takes ~6 weeks for positive results. Conclusion: Therefore, we suggest that the efficacy of the PCR should be tested on larger population and a definite diagnosis should be made before the start of any therapy.

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