Molecular characterisation of <it>Mycobacterium tuberculosis </it>isolates in the First National Survey of Anti-tuberculosis Drug Resistance from Venezuela

• Main Authors: Rastogi Nalin, Ramírez Carmen, Martín Carlos, Revillo María J, Lezcano María A, Lafoz Carmen, Guilarte Alexis, España Mercedes, Armengol Raimond, Cebollada Alberto, Aristimuño Liselotte, Rojas Janet, de Salas Albina, Sola Christophe, Samper Sofía
• Format: Article
• Language: English
• Published: BMC 2006-10-01
• Series: BMC Microbiology
• Online Access: http://www.biomedcentral.com/1471-2180/6/90

<p>Abstract</p> <p>Background</p> <p>Molecular typing of <it>Mycobacterium tuberculosis </it>strains has become a valuable tool in the epidemiology of tuberculosis (TB) by allowing detection of outbreaks, tracking of epidemics, identification of genotypes and transmission events among patients who would have remained undetected by conventional contact investigation. This is the first genetic biodiversity study of <it>M. tuberculosis </it>in Venezuela. Thus, we investigated the genetic patterns of strains isolated in the first survey of anti-tuberculosis drug-resistance realised as part of the Global Project of Anti-tuberculosis Drug Resistance Surveillance (WHO/IUATLD).</p> <p>Results</p> <p>Clinical isolates (670/873) were genotyped by spoligotyping. The results were compared with the international spoligotyping database (SpolDB4). Multidrug resistant (MDR) strains (14/18) were also analysed by IS<it>6110</it>-RFLP assays, and resistance to isoniazid and rifampicin was characterised.</p> <p>Spoligotyping grouped 82% (548/670) of the strains into 59 clusters. Twenty new spoligotypes (SITs) specific to Venezuela were identified. Eight new inter-regional clusters were created. The Beijing genotype was not found. The genetic network shows that the Latin American and Mediterranean family constitutes the backbone of the genetic TB population-structure in Venezuela, responsible of >60% of total TB cases studied. MDR was 0.5% in never treated patients and 13.5% in previously treated patients. Mutations in <it>rpoB </it>gene and <it>katG </it>genes were detected in 64% and 43% of the MDR strains, respectively.</p> <p>Two clusters were found to be identical by the four different analysis methods, presumably representing cases of recent transmission of MDR tuberculosis.</p> <p>Conclusion</p> <p>This study gives a first overview of the <it>M. tuberculosis </it>strains circulating in Venezuela during the first survey of anti-tuberculosis drug-resistance. It may aid in the creation of a national database that will be a valuable support for further studies.</p>