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.