Molecular Characterization of Mycobacterium avium Complex Isolates Giving Discordant Results in AccuProbe Tests by PCR-Restriction Enzyme Analysis, 16S rRNA Gene Sequencing, and DT1-DT6 PCR

Devallois, A and Picardeau, M and Paramasivan, C N and Vincent, V and Rastogi, N (1997) Molecular Characterization of Mycobacterium avium Complex Isolates Giving Discordant Results in AccuProbe Tests by PCR-Restriction Enzyme Analysis, 16S rRNA Gene Sequencing, and DT1-DT6 PCR. Journal of Clinical Microbiology, 35 (11). pp. 2767-2772. ISSN Print: 0095-1137; Online: 1098-660X

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Abstract

Based on cultural and biochemical tests, a total of 84 strains (72 clinical and 12 environmental isolates from the Caribbean Isles, Europe, and the Indian subcontinent) were identified as members of the Mycobacterium avium complex (MAC). They were further characterized with MAC, M. avium, and M. intracellulare probes of the AccuProbe system, and this was followed by selective amplification of DT6 and DT1 sequences. Seventy isolates gave concordant results; 63 were identified as M. avium, 5 were identified as M. intracellulare, and 24 remained untypeable by both methods. Fourteen isolates gave discrepant results, as they were DTl positive but gave negative results by the M. intracellulare AccuProbe test. Consequently, a detailed molecular analysis of all DT1-positive isolates (14 discrepant strains plus 5 M. intracellulare strains) was performed by PCR-restriction analysis (PRA) of the hsp65 gene and 16S rRNA gene sequencing. The results confirmed the reported heterogeneity of M. intracellulare, as only 6 of 19 isolates (32%) gave PRA results compatible with published M. intracellulare profiles while the rest of the isolates were grouped in four previously unpublished profiles. 16S rRNA gene sequencing showed that only 8 of 19 isolates (4270) were related to M. intracellulare IWGMT 90247 (EMBL accession no. X88917), the rest being related to MCRO19 (EMBL accession no. X93030) and MIWGTMR10 (EMBL accession no. X88915). In conclusion, we have characterized a significant number of MAC isolates which were not identified by the AccuProbe test, PRA, or 16S rRNA sequencing. However, all of them were identifiable by DTl-DT6 PCR (they were DT6 negative and DTl positive) and could be tentatively identified as M. intracellufure based on preliously published observations. It is noteworthy that the majority of such isolates (14 of 19) were from the Indian subcontinent, with 12 of 14 being environmental isolates. Our study confirms the marked heterogeneity of-V. intrucellulare isolates and shows the utility of in-house DTl PCR to detect this group of isolates, which

Item Type:	Article
Subjects:	Tuberculosis > Laboratory Research > Bacteriological
Divisions:	Basic Science Research > Bacteriology
Depositing User:	Dr. Rathinasabapati R
Date Deposited:	30 Sep 2013 09:47
Last Modified:	14 Mar 2016 04:40
URI:	http://eprints.nirt.res.in/id/eprint/433

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