Time to identify and define non-tuberculous mycobacteria in a tuberculosis-endemic region
Abstract:OBJECTIVE: To identify and characterise disease caused by non-tuberculous mycobacteria (NTM) in a tuberculosis-endemic region.
MATERIAL AND METHODS: A total of 133 NTM isolates cultivated using Mycobacteria Growth Indicator Tube 960 (MGIT 960) plus Löwenstein-Jensen (LJ) and identified using the NAP and PNBA tests were screened to species level using molecular methods. The 360-base pair (bp) region of the rpoB gene was amplified and analysed using an in-house RLBH assay, PCR-RE and sequencing. The clinical significance of all isolated NTM was determined as per published guidelines.
RESULTS AND DISCUSSION: Of the 133 isolates, 127 were confirmed as NTM and six as Mycobacterium tuberculosis complex by molecular methods; 81% of the NTM were recovered from pulmonary and 19% from extra-pulmonary specimens. Among the rapidly growing NTM, M. fortuitum (41%) and M. abscessus (59%) were predominant. Among the slow growing NTM, 40% were identified as M. intracellulare, followed by M. simiae (35%), M. kansasii (6%), M. gordonae (4%) M. szulgai (2%) and M. avium (1%). Mixed infections were noted in 10 (12%) cases. In all, 58 (46%) NTM met clinical, radiological and microbiological criteria and were considered definite NTM infections, 33 (26%) were highly probable disease and 36 (28%) were possible disease or colonisation.
CONCLUSION: Overall, 72% of isolated NTM were found to be clinically significant. Accurate species identification and adherence to published guidelines help to outline pathogenicity.
Document Type: Regular Paper
Affiliations: Department of Microbiology, P D Hinduja National Hospital & Medical Research Centre, Mahim (West), Mumbai, India
Publication date: August 1, 2010
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