Genetic variability of Mycobacterium tuberculosis complex in patients with no known risk factors for MDR-TB in the North-eastern part of Lima, Peru

BACKGROUND The aim of this study was to investigate the genetic diversity among Mycobacterium tuberculosis complex circulating in patients with no known risk factors for multi-drug resistant (MDR) tuberculosis (TB) living in a high MDR burden area and analyze the relationship between genotypes, primary drug resistance and age. METHODS Samples were collected during January-July 2009. Isolates were tested for drug susceptibility to first-line drugs and were genotyped by spoligotyping and the 15-loci Mycobacterial Interspersed Repetitive Unit (MIRU15). RESULTS Among the 199 isolates analyzed, 169 (84.9%) were identified in the SpolDB4.0 and 30 (15.1%) could not be matched to any lineage. The most prevalent lineage was Haarlem (29.6%), followed by T (15.6%), Beijing (14.1%), Latin American Mediterranean (12.6%) and U (8.5%). A few isolates belonged to the X and S clades (4.5%). Spoligotype analysis identified clustering among 148 of 169 isolates, whereas with MIRU15 all isolates were unique. Out of 197 strains; 31.5% were resistant to at least one drug, 7.5% were MDR and 22.3% showed any resistance to isoniazid. CONCLUSION In contrast with other Latin-American countries where LAM lineage is the most predominant, we found the spoligotype 50 from the Haarlem lineage as the most common. None of the prevailing lineages showed a significant association with age or resistance to isoniazid and/or rifampicin.