Genotypic identification of members of the Mycobacterium avium complex isolated from pulmonary infections in Pará State, Brazil

Abstract

ABSTRACT

INTRODUCTION: The Mycobacterium avium complex (MAC) is a group of slow-growing mycobacteria naturally found in the environment capable of causing infections in a wide variety of living species, including birds, swines and humans. These infections can be asymptomatic, clinically significant and, in some cases, fatal. There is a demand for techniques that are capable of conclusively identifying closely related bacteria. Molecular biological techniques are promising tools for a more precise identification.
MATERIAL AND METHODS: In this study, we evaluated the ability of 16S rRNA, hsp65 and rpoB molecular markers to distinguish between members of the MAC isolated in the Mycobacteria Laboratory at the Instituto Evandro Chagas.
RESULTS: MAC samples collected from 15 patients were previously evaluated using an hsp65 gene restriction fragment length polymorphism analytical method (RFLP-hsp65), and they showed three different profiles: (I) BstEII: 235/115/100, HaeIII: 145/130/60; (II) BstEII: 235/210, HaeIII: 130/105; and (III) BstEII: 235/210, HaeIII: 145/130. We constructed phylogenetic trees using 16S rRNA analysis in which the samples were distributed into two groups, similarly to those found in the hsp65 analysis. However, the results from the rpoB analysis disagreed with those of the other trees due to changes in topology.
CONCLUSION: The findings from this study warrant that various evolutionary forces may be acting on the rpoB gene. Thus, it is necessary to be cautious when using this target for taxonomic analyses. Additionally, we recommend that multiple markers (including16S rRNA) be evaluated when identifying mycobacteria.