Molecular Assessment, Drug-Resistant Profile, and Spacer Oligonucleotide Typing (Spoligotyping) of Mycobacterium tuberculosis Strains From Tamaulipas, México

Background: Tuberculosis remains a serious global health problem involving one-third of the world population. A wide diversity of Mycobacterium tuberculosis strains cause about 1.5 million deaths/year worldwide, but in developing countries, the genetic diversity of M. tuberculosis strains remains largely unknown. We conducted a first insight into the population diversity of M. tuberculosis strains from Tamaulipas, Mexico. Methods: Seventy-two M. tuberculosis strains were identified and genetic diversity determined by spoligotyping. Drug sensibility testing and punctual mutations in inhA, ahpC, rpoB, and katG genes were assessed. Results: Spoligotyping analysis showed a higher prevalence of LAM9 > T1 > Haarlem3 subfamilies among 53 spoligotype patterns. Unexpectedly, five Beijing strains conforming four unique spoligopatterns were recovered. The more frequently isolated strains (LAM9 and T1), but none of the Beijing strains, were found resistant to INH or RIF. Also, no drug resistance was found among Haarlem3 isolates. The katG³¹⁵ gene mutation was found in 83% of INH-resistant strains, whereas rpoB⁵²⁶ were associated in only 43% of RIF M. tuberculosis drug-resistant strains. Conclusions: This and other studies report a high rate of orphan spoligotypes, which highlights the need for genotyping implementation as a routine technique for better understanding of M. tuberculosis strains in developing countries such as Mexico.