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

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.

Description of the population structure and genetic diversity of tuberculosis in Estado de México, a low prevalence setting from Mexico

“…The geographical location of these lineages in the state did not show a predominance or specific pattern of any lineage within a specific region. All of the four major lineages identified in this study have been described worldwide , including other locations in Mexico, such as Monterrey and San Luis Potosí in the North , Guerrero in the Southwest , Distrito Federal in the center , Veracruz in the Southeast , and a set of multidrug resistant isolates from across the country .…”

“…It is notable that only seven isolates showed an East‐Asian, Indo‐Oceanic or East‐African‐Indian lineage, particularly when we consider the close proximity of Estado de México with the two most important contributors of these lineages in Mexico: Guerrero and San Luis Potosí . These lineages, especially Beijing, are traditionally considered to be highly virulent, with a strong tendency toward drug resistance and dominance in Asian populations; however, distribution in Latin America seems to be discrete and rarely associated with significant outbreaks .The low occurrence of these lineages in the region could have two possible explanations: The first is related to the recent incorporation of these lineages in Estado de México and the second is the containment of their dispersion by the dominant circulating lineages that can rapidly infect the susceptible population.…”

“…Only 57 (31%) isolates were associated in nine clusters, the three most important of which were SIT119 (X1), SIT53 (T1) and SIT50 (Haarlem3). These SITs are frequently described worldwide, including Mexico . Of the main cluster, SIT119 (X1), only two isolates shared the MIT116.…”

“…Despite the fact that Mexico is one of the most important contributors of TB cases in the Americas, reports describing the genetic characteristics of the circulating isolates remain scarce .…”

Comparative Mycobacterium tuberculosis Spoligotype Distribution in Mexico

“…In this study, we observed that the most predominant tuberculosis subtype is SIT53; this SIT has also been found to be the most common in the nearby regions of San Luis Potosi (600 km from Monterrey [7]) and Guadalajara (near the Pacific side of the country [8]) (Fig. 2).…”