Evaluation of partial 16S rRNA gene sequencing for identification of clinical isolates of non-tuberculous mycobacteria in a routine mycobacterial laboratory

Abstract number: 1733_1478

Insa R., Marín M., Ruiz Serrano M.J., del Rosal M., Goyanes M.J., García de Viedma D., Bouza E.

Objectives: Conventional identification of non-tuberculous mycobacteria (NTM) is based on biochemical characteristics, PCR-RFLP (PRA) or a combination of both. Both techniques are time consuming and occasionally produce discordant identification. The aim of this study is to evaluate the utility of the amplification and sequencing of the 5' end 16S rRNA gene (16S-PCR) in the identification of clinical isolates of NTM in comparison with both conventional techniques.

Methods: NTM were characterised by: (i) biochemical and phenotypical characteristics, (ii) PRA and (iii) 16S-PCR. The 16S sequences were compared with those included in Genebank and Ridom. Only alignments with similarities higher than 99% were considered. Results obtained by 16S-PCR were compared with our gold standard (biochemical test plus PRA results)

Results: Overall we evaluated 52 isolates from different patients. Biochemical tests and PRA matched exactly in 42 isolates: M. fortuitum (6), M. abscessus (1), M. chelonae (2), M. xenopi (5), M. gordonae (6), M. avium–intracellulare (5), M. celatum (3), M. kansasii (5), M. peregrinum (1), M. lentiflavum (3), M. simiae (2), M. smegmatis (2) and M. thermorresistibile (1). Results obtained by 16S-PCR agree with that gold standard in 90.5% (38/42). In 10 isolates there was disagreement between biochemical test and PRA. Among these cases, 16S-PCR supported the result obtained by biochemical test in 5/6 and PRA in 1/6. In 4 isolates each of the three methods provided a different identification. 16S-PCR was able to recognize two new species: M. wolinskyi and M. mageritense.

Conclusions: 16S-PCR could be useful for a preliminary and rapid identification of NTM but needs to be complemented by one of the conventional methods, preferably biochemical tests. The analysis of other conserved genes could contribute to a more accurate identification.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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