First insights into the genetic diversity of Mycobacterium tuberculosis isolates from HIV-infected Mexican patients and mutations causing multidrug resistance

Departamento de Microbiologia, ENCB-IPN, Mexico City, Mexico.
BMC Microbiology (Impact Factor: 2.73). 03/2010; 10(1):82. DOI: 10.1186/1471-2180-10-82
Source: PubMed


The prevalence of infections with Mycobacterium tuberculosis (MTb) and nontuberculous mycobacteria (NTM) species in HIV-infected patients in Mexico is unknown. The aims of this study were to determine the frequency of MTb and NTM species in HIV-infected patients from Mexico City, to evaluate the genotypic diversity of the Mycobacterium tuberculosis complex strains, to determine their drug resistance profiles by colorimetric microplate Alamar Blue assay (MABA), and finally, to detect mutations present in katG, rpoB and inhA genes, resulting in isoniazid (INH) and rifampin (RIF) resistance.
Of the 67 mycobacterial strains isolated, 48 were identified as MTb, 9 as M. bovis, 9 as M. avium and 1 as M. intracellulare. IS6110-RFLP of 48 MTb strains showed 27 profiles. Spoligotyping of the 48 MTb strains yielded 21 patterns, and 9 M. bovis strains produced 7 patterns. Eleven new spoligotypes patterns were found. A total of 40 patterns were produced from the 48 MTb strains when MIRU-VNTR was performed. Nineteen (39.6%) MTb strains were resistant to one or more drugs. One (2.1%) multidrug-resistant (MDR) strain was identified. A novel mutation was identified in a RIF-resistant strain, GAG --> TCG (Glu --> Ser) at codon 469 of rpoB gene.
This is the first molecular analysis of mycobacteria isolated from HIV-infected patients in Mexico, which describe the prevalence of different mycobacterial species in this population. A high genetic diversity of MTb strains was identified. New spoligotypes and MIRU-VNTR patterns as well as a novel mutation associated to RIF-resistance were found. This information will facilitate the tracking of different mycobacterial species in HIV-infected individuals, and monitoring the spread of these microorganisms, leading to more appropriate measures for tuberculosis control.

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Available from: Jorge A Gonzalez-Y-Merchand, Mar 20, 2015
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    • "Some of the NTM identified in our study included species that have been frequently associated with human illness in other countries, such as: M. avium, M. fortuitum, and M. mucogenicum[31]. In Mexico City, the prevalence of NTM infections is poorly known and few studies have been published, among them, Lopez-Alvarez et al.[32] reported in 2010 that 15% of mycobacterial strains isolated from 67 HIV patients belonged to NTM (10 strains were identified as M. avium and 1 as M. intracellulare). In another recent study, Cortes-Torres et al.[33] in 2013 reported that 37% of 96 patients in a Mexico City Hospital, with various immunodeficiencies, presented various strains of NTM, of which 23 were M. avium, 9 M. "
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    ABSTRACT: Slovenia is one of the few countries where IS6110 RFLP is applied for genotyping M. tuberculosis at a nationwide level, which has been in effect since 2000. Based on S6110 RFLP clustering, typical risk factors and routes of M. tuberculosis transmission were identified, such as alcohol abuse, homelessness, and bars. However, IS6110 RFLP typing suffers from important limitations including a long wait for results, which reduces the potential benefit of molecular-guided tuberculosis (TB) control. PCR-based 24-locus MIRU-VNTR typing combined with spoligotyping has recently emerged as a potential alternative for faster, large-scale genotyping of M. tuberculosis. We compared these genotyping methods for analyzing 196 Slovenian Mycobacterium tuberculosis isolates representing 97.5% of all culture-positive cases included in the Slovenian TB Registry in 2008. IS6110 RFLP and 24-locus MIRU-VNTR typing combined with spoligotyping identified 157 and 155 distinct profiles, 135 and 125 unique isolates, and 61 and 71 clustered isolates grouped into 22 and 29 clusters, respectively. The discriminatory indexes were very close, at 0.9963 and 0.9965, respectively. The majority of the molecular clusters defined by either of the two methods were identical, including in the few cases for which epidemiological links were available. The differences frequently consisted of single-band changes in IS6170-RFLP profiles subdividing a MIRU-VNTR/spoligotype-based cluster. Our one-year nationwide study showed that the results of 24-locus MIRU-VNTR typing combined with spoligotyping reached a high level of concordance with those obtained from IS6110 RFLP typing.
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