Dados do Trabalho

Título

Detection of different profiles for identification and drug susceptibility of the M. abscessus group using diverse routine methodologies

Introdução

Mycobacterium abscessus group (MAG), which causes pulmonary and extrapulmonary diseases, is the most drug-resistant nontuberculous mycobacteria, resulting in limited therapeutic options and a high rate of treatment failure. In addition to providing data for epidemiological surveillance, the correct identification of subspecies is also important for clinicians, as they differ in antimicrobial susceptibility and affect the patient's prognosis.

Objetivo (s)

The present study aimed to clarify discordant results between tests used in routine diagnosis for identification of MAG isolates. 

Material e Métodos

Isolates of MAG, received at Institute Adolfo Lutz between 2010 and 2012 for diagnosis purposes, were identified by the PRA-hsp65 method, NTM-DR Genotype (Hain Lifescience) and Sanger Sequencing (SS) of the hsp65 and rpoB genes. PCR of the erm(41) gene fragment, real-time multiplex PCR with detection of erm(41) fragments, T28C allele and rrl A2058 allele and erm(41) and rrl genes SS were performed to detect clarithromycin (CLA) resistance, in addition to the drug susceptibility tests by minimum inhibitory concentration, as recommended by CLSI. Whole genome sequencing (WGS) was performed on the MiSeq platform (Illumina). A series of core SNPs were generated for phylogenetic analysis and subspecies identification. 

Resultados e Conclusão

Of the 206 isolates analyzed in the period, 20 isolates were selected for WGS, 13 because they presented discrepancies between identifications or susceptibility to CLA and seven presented concordant profiles and were used, as they presented expected results, to compose the phylogenetic tree. A concordance rate of 95% (n=19/20) was observed for hsp65 gene SS and PRA-hsp65 method, 85% (n=17/20) for Genotype NTM-DR and 70% (n=14/20) for rpoB gene SS. Two strains, classified as M. a. bolletii by WGS phylogenetic positioning, also showed discrepant results between rpoB and other methods, we found a mixture of previously defined M. a. bolletii and M. a. massiliense specific marker genes. Two isolates of M. a. abscessus, with phenotypic CLA susceptible profile, suffered a deletion in erm(41), commonly found in the subspecies M. a. massiliense. Three M. a. abscessus and one M. a. massiliense presented different resistance profile suggesting another resistance mechanism. Therefore, the use of phenotypic methods is of great importance for correct therapy, until the majority of resistance profiles are known.

Palavras Chave

mycobacteriosis; resistance; treatment