Genetic diversity of the Mycobacterium tuberculosis Complex in San Luis Potosí, México

Estela López-Rocha,José A Enciso-Moreno,Rubén López-Revilla,Lina Riego-Ruiz,Julio Juárez-Álvarez,Julián Hernández-Nieto,Leonor Enciso-Moreno,Francisco Ortega-Aguilar

doi:10.1186/1756-0500-6-172

Abstract

BackgroundAlthough epidemiologic and socioeconomic criteria and biomedical risk factors indicate high-priority for tuberculosis (TB) control in Mexico, molecular epidemiology studies of the disease in the country are scarce.MethodsComplete sociodemographic and clinical data were obtained from 248 of the 432 pulmonary TB (PTB) cases confirmed from 2006 to 2010 on the population under epidemiological surveillance in the state of San Luis Potosí, México. From most PTB cases with complete data Mycobacterium tuberculosis complex (MTC) isolates were recovered and their spoligotypes, lineages and families, geographic distribution and drug resistance determined.ResultsPulmonary tuberculosis incidence ranged from 2.4 to 33.4 (cases per 100,000 inhabitants) in the six state sanitary jurisdictions that were grouped in regions of low (jurisdictions I-II-III), intermediate (jurisdictions IV-V) and high incidence (jurisdiction VI) with 6.2, 17.3 and 33.4 rates, respectively. Most patients were poor, 50-years-median-age males and housewives. Among the 237 MTC spoligotyped isolates, 232 corresponded to M. tuberculosis (104 spoligotypes in 24 clusters) and five to M. bovis. The predominant Euro-American lineage was distributed all over the state, the East-Asian lineage (Beijing family) in the capital city, the Indo-Oceanic (Manila family) in eastern localities, and M. bovis in rural localities.ConclusionsIn San Luis Potosí TB affects mainly poor male adults and is caused by M. tuberculosis and to a minor extent by M. bovis. There is great genotypic diversity among M. tuberculosis strains, the Euro-American lineage being much more prevalent than the Indo-Oceanic and East-Asian lineages. The frequency of resistant strains is relatively low and not associated to any particular lineage.

Highlights

Epidemiologic and socioeconomic criteria and biomedical risk factors indicate high-priority for tuberculosis (TB) control in Mexico, molecular epidemiology studies of the disease in the country are scarce
We confirmed that in San Luis Potosí pulmonary TB (PTB) incidence correlates with low socioeconomic status since nearly two thirds of the patients resided in rural communities and more than half of them lived in highly marginalized municipalities
The same lineage has been shown to be prevalent in the Mexican cities of Orizaba [5] and Monterrey [11], and we found it to be the most prevalent in San Luis Potosí (95.3%) with SIT53, SIT42, SIT20, SIT221, SIT239, SIT50, SIT787, SIT17 and SIT258 as its main genotypes

Summary

Introduction

Epidemiologic and socioeconomic criteria and biomedical risk factors indicate high-priority for tuberculosis (TB) control in Mexico, molecular epidemiology studies of the disease in the country are scarce. The national TB incidence is relatively low, the weight of epidemiologic and socioeconomic criteria and biomedical. TB reemergence, its association with the HIV-AIDS and diabetes epidemics [4,5] and the emergence and spread of MDR strains demand that epidemiological and genotyping data of Mycobacterium tuberculosis Complex (MTC) isolates be used to identify chains of transmission [6] and to differentiate TB cases due to endogenous reactivation [7]. Spoligotyping, based on the polymorphism of spacer sequences of the direct repeat region (DR) is used to differentiate MTC isolates [8]. Spoligotyping identifies M. bovis strains, which usually carry few IS6110 copies [10]

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