Importance of using several molecular targets for the appropriated identification of Mycobacterium marinum

Abstract

M. marinum is a non-tuberculous mycobacterium capable of producing human infection with variable incidence, often under diagnosed due to the difficulties of isolation and culture. There is a description of a M. marinum infection in which the molecular identification required the use of several polymorphic sequences. From ulcerated papules and purulent discharge patient lesion histopathology, bacteriological identification by biochemical tests and molecular identification using PCR-restriction fragment length polymorphism analysis (PRA) of 3 polymorphic sequences with two regions of hsp65 gene and an intergenic non-transcribed spacer of 16S-23S rDNA was performed.Histopathological studies showed granulomatous lesions with inflammatory cell infiltrate. The isolation and bacteriological identification showed the causal agent to be M. marinum. However, the initial genotypic identification, using mostly polymorphic sequence of the hps65 gene, did not discriminate from M. marinum and M. malmöense type I, requiring the use of other PRA to confirm the diagnosis of M. marinum. The joint application of bacteriological and molecular techniques established the diagnosis. We suggest that there is necessary to include more than one molecular target to achieve the identification of these mycobacteria species.

Application of a new designed high resolution melting analysis for mycobacterial species identification

“…Therefore, using several housekeeping genes and Multilocus Sequence Analysis (MLSA) method based on concatenated sequences to diagnose Mycobacterium species is one of the ways to overcome discrimination limitations [17][18][19]. The high-resolution curve melting (HRM) assay is a method for identifying Mycobacterial species.…”