Publications by authors named "Carlos A Vazquez Chacon"

6 Publications

  • Page 1 of 1

Molecular epidemiology of Mycobacterium tuberculosis in Baja California, Mexico: A result of human migration?

Infect Genet Evol 2017 11 11;55:378-383. Epub 2016 Jul 11.

Laboratorio de Epidemiología y Ecología Molecular, Escuela de Ciencias de la Salud, Universidad Autónoma de Baja California, Ensenada, Baja California, Mexico; Red Multidisciplinaria de Investigación en Tuberculosis, Mexico. Electronic address:

The State of Baja California (BC) exhibits the highest incidence and prevalence rates of tuberculosis (TB), and multidrug-resistant TB (MDR-TB) in Mexico. However information about the circulation of M. tuberculosis lineages in BC and Mexico as a whole is limited. Here, we describe the genetic relationship and genetic diversity among M. tuberculosis clinical isolates (n=140) collected in BC between October 2009 and April 2011 with other regions of Mexico, the United States, and Latin America. All specimens were genotyped based on 24 mycobacterial interspersed repetitive units (MIRU)-variable number of tandem repeats (VNTR) loci. Population structure and minimum spanning tree (MST) analyses were used to assess the genetic diversity and distribution of BC isolates in comparison to USA and South America strains. Among the nine lineages observed, LAM, Haarlem and S were the most frequent identified in BC. Population structure analysis clustered most BC isolates (41%) into three distinctive groups that included strains from San Diego and South America, whereas other BC strains (22%) clustered with other Mexican strains. A subset of isolates (12%) seemed to be autochthonous of BC, while 25% were cosmopolitan and grouped into multiple clusters. It is highly likely that the TB genetic structure observed in BC is due to human migration. Additional studies are required to determine the mechanism involved in the phylogeographic distribution of M. tuberculosis in Mexico. Implementation of domestic molecular TB surveillance programs is required to better understand the molecular epidemiology of TB not only in the region but at the national level.
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http://dx.doi.org/10.1016/j.meegid.2016.07.001DOI Listing
November 2017

Human multidrug-resistant Mycobacterium bovis infection in Mexico.

Tuberculosis (Edinb) 2015 Dec 13;95(6):802-809. Epub 2015 Aug 13.

Instituto de Diagnóstico y Referencia Epidemiológicos, Secretaría de Salud, Mexico City, Mexico.

Here, we describe the molecular characterization of six human Mycobacterium bovis clinical isolates, including three multidrug resistant (MDR) strains, collected in Mexico through the National Survey on Tuberculosis Drug Resistance (ENTB-2008), a nationally representative survey conducted during 2008-2009 in nine states with a stratified cluster sampling design. The genetic background of bovine M. bovis strains identified in three different states of Mexico was studied in parallel to assess molecular relatedness of bovine and human strains. Additionally, resistance to first and second line anti-tuberculosis (TB) drugs and molecular identification of mutations conferring drug resistance was also performed. All strains were characterized by spoligotyping and 24-loci MIRU-VNTRs, and analyzed using the SITVIT2 (n = 112,000 strains) and SITVITBovis (n = 25,000 strains) proprietary databases of Institut Pasteur de la Guadeloupe. Furthermore, data from this study (n = 55 isolates), were also compared with genotypes recorded for M. bovis from USA (n = 203), Argentina (n = 726), as well as other isolates from Mexico (independent from the present study; n = 147), to determine any evidence for genetic relatedness between circulating M. bovis strains. The results showed that all human M. bovis cases were not genetically related between them or to any bovine strain. Interestingly, a high degree of genetic variability was observed among bovine strains. Several autochthonous and presumably imported strains were identified. The emergence of drug-resistant M. bovis is an important public health problem that jeopardizes the success of TB control programs in the region.
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http://dx.doi.org/10.1016/j.tube.2015.07.010DOI Listing
December 2015

Vertical transmission of hepatitis C virus: a tale of multiple outcomes.

Infect Genet Evol 2013 Dec 18;20:465-70. Epub 2013 Oct 18.

Instituto de Diagnóstico y Referencia Epidemiológicos, Mexico City, Mexico.

Globally, hepatitis C virus (HCV) infection affects approximately 130 million people and 3 million new infections occur annually. HCV is also recognized as an important cause of chronic liver disease in children. The absence of proofreading properties of the HCV RNA polymerase leads to a highly error prone replication process, allowing HCV to escape host immune response. The adaptive nature of HCV evolution dictates the outcome of the disease in many ways. Here, we investigated the molecular evolution of HCV in three unrelated children who acquired chronic HCV infection as a result of mother-to-child transmission, two of whom were also coinfected with HIV-1. The persistence of discrete HCV variants and their population structure were assessed using median joining network and Bayesian approaches. While patterns of viral evolution clearly differed between subjects, immune system dysfunction related to HIV coinfection or persistent HCV seronegativity stand as potential mechanisms to explain the lack of molecular evolution observed in these three cases. In contrast, treatment of HCV infection with PegIFN, which did not lead to sustained virologic responses in all 3 cases, was not associated with commensurate variations in the complexity of the variant spectrum. Finally, the differences in the degree of divergence suggest that the mode of transmission of the virus was not the main factor driving viral evolution.
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http://dx.doi.org/10.1016/j.meegid.2013.10.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5042690PMC
December 2013

Genetic diversity among multidrug-resistant Mycobacterium tuberculosis strains in Mexico.

Infect Genet Evol 2013 Mar 16;14:434-43. Epub 2013 Jan 16.

Instituto de Diagnóstico y Referencia Epidemiológicos, Secretaría de Salud, Mexico City, Mexico.

Tuberculosis is an important public health problem in Mexico. However, limited information about the genetic diversity of Mycobacterium tuberculosis strains circulating in the country is available. In this work, 109 multidrug-resistant (MDR) M. tuberculosis isolates collected in 23 different states of Mexico in 2003 were retrospectively characterized by spoligotyping and MIRU-VNTRs. All isolates, except for a single cluster containing two strains (subcluster E1), were split when information from the 12-loci MIRUs and spoligo-pattern was simultaneously analyzed. The discriminative power of 12-loci MIRU-VNTR and spoligotyping, by the Hunter-Gaston index, were 0.9998 and 0.9011, respectively. These findings suggest that almost all cases were epidemiologically unrelated. Instead, the genetic variations observed among these strains are suggestive of emergence of acquired drug-resistance during the course of treatment. The results suggest a high degree of genetic variability and a high frequency of SIT53 (T1 family) spoligotype among the MDR M. tuberculosis isolates included in the study.
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http://dx.doi.org/10.1016/j.meegid.2012.12.024DOI Listing
March 2013

Rapid hepatitis C virus divergence among chronically infected individuals.

J Clin Microbiol 2013 Feb 5;51(2):629-32. Epub 2012 Dec 5.

Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico.

Here, we analyze the viral divergence among hepatitis C virus (HCV) chronic cases infected with genotype 1. The intrahost viral evolution was assessed by deep sequencing using the 454 Genome Sequencer platform. The results showed a rapid nucleotide sequence divergence. This notorious short-term viral evolution is of the utmost importance for the study of HCV transmission, because direct links between related samples were virtually lost. Thus, rapid divergence of HCV significantly affects genetic relatedness studies and outbreak investigations.
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http://dx.doi.org/10.1128/JCM.03042-12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3553878PMC
February 2013
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