Multidrug-resistant nontuberculous mycobacteria isolated from cystic fibrosis patients

Abstract

Worldwide, nontuberculous mycobacteria (NTM) have become emergent pathogens of pulmonary infections in cystic fibrosis (CF) patients, with an estimated prevalence ranging from 5 to 20%. This work investigated the presence of NTM in sputum samples of 129 CF patients (2 to 18 years old) submitted to longitudinal clinical supervision at a regional reference center in Rio de Janeiro, Brazil. From June 2009 to March 2012, 36 NTM isolates recovered from 10 (7.75%) out of 129 children were obtained. Molecular identification of NTM was performed by using PCR restriction analysis targeting the hsp65 gene (PRA-hsp65) and sequencing of the rpoB gene, and susceptibility tests were performed that followed Clinical and Laboratory Standards Institute recommendations. For evaluating the genotypic diversity, pulsed-field gel electrophoresis (PFGE) and/or enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) was performed. The species identified were Mycobacterium abscessus subsp. bolletii (n = 24), M. abscessus subsp. abscessus (n = 6), Mycobacterium fortuitum (n = 3), Mycobacterium marseillense (n = 2), and Mycobacterium timonense (n = 1). Most of the isolates presented resistance to five or more of the antimicrobials tested. Typing profiles were mainly patient specific. The PFGE profiles indicated the presence of two clonal groups for M. abscessus subsp. abscessus and five clonal groups for M. abscesssus subsp. bolletii, with just one clone detected in two patients. Given the observed multidrug resistance patterns and the possibility of transmission between patients, we suggest the implementation of continuous and routine investigation of NTM infection or colonization in CF patients, including countries with a high burden of tuberculosis disease.

FIG 1

Dendrogram obtained from the automated analysis of the ERIC-PCR profiles of the M. fortuitum isolates, showing the similarity coefficients (as percentages). Dice's coefficient was used as the algorithm for the construction of the dendrogram.

FIG 2

Dendrogram obtained from the automated analysis of the PFGE profiles of the M. abscessus subsp. abscessus isolates, showing the similarity coefficients (as percentages). Dice's coefficient was used as the algorithm for the construction of the dendrogram.

FIG 3

Dendrogram obtained from the automated analysis of the PFGE profiles of the M. abscessus subsp. bolletii isolates, showing the similarity coefficients (as percentages). Dice's coefficient was used as the algorithm for the construction of the dendrogram.