Silent presence of non- tuberculous mycobacterium (NTM) has been observed since last 100 years, but now the increasing incidence of NTM is threatening the successful implementation of ongoing Tuberculosis control programme. While for identification and control of Mycobacterium tuberculosis many advanced efforts are being made, at the same time the silently growing menace of non-tuberculous mycobacterium is receiving little attention. This study is aimed at providing early and accurate detection of NTM from isolated mycobacterium by using routine biochemical tests. In the laboratory, specimen were processed by modified Petroff”s and cultured in a pair of Lowenstein Jensen (LJ) medium and MGIT culture, samples were processed by NALC - NaOH method, and inoculated in MGIT culture tube. The LJ medium were incubated at 37°C for 8 weeks and LJ slopes were examined daily for one weak and then every week for colonies of acid fast bacilli (AFB). Once the growth appeared, it was confirmed by Ziehl-Neelsen staining. Mycobacterium isolates were identified by batteries of biochemical tests. All the identification tests were standardized and monitored by including standard mycobacterium cultures as positive and negative controls. During the study period, a total of 4104 culture positive for Mycobacterium were found which included LJ positive (3060) and MGIT positive (1044) cultures. The total 60 mycobacterium growths were identified as NTM which included 41 NTM from LJ positive culture & 19 from MGIT culture. NTM isolated using LJ culture from the male was 29 & in female 12. In MGIT culture system NTM isolated were 13 from male and 06 from female Tb suspects. The mycobacterium species identification results showed that NTM isolated in our laboratory belong to all the 4 groups of runyon classification. Total number of NTM found was as follows: in Gr1 (5,) Gr 11 (08), Gr111 (31) and Gr1V (16). The most common species identified in this study was M. simae (12%) followed by M. avium (10), M.gordonae (08%) and M. kansasi (08%) etc. The study showed that most of the NTMs were isolated from sputum (37%) followed by pleural pus (21.66), Lymph node aspirate (20%), pleural fluid (7%), bronchial wash (8%), pus (3%), CSF (1.66%) and ascitic fluid (1.66%). The isolation of NTMs from all types of samples indicated that they not only cause pulmonary but are also responsible for extra pulmonary diseases. This study is giving a clear message to clinical microbiologists that any positive growth of Mycobacterium cannot be left for discard till the whole process of identification and sensitivity of the organism is complete.

Download this article as