Multi-drug resistant Mycobacterium tuberculosis complex genetic diversity and clues on recent transmission in Punjab, Pakistan

• Published in: Infection, genetics and evolution genetics and evolution, 2014-10, Vol.27, p.6-14
• Main Authors: Yasmin, Memona, Gomgnimbou, Michel K, Siddiqui, Rubina T, Refrégier, Guislaine, Sola, Christophe
• Format: Article
• Language: English
• Subjects: Antitubercular Agents - pharmacology; Cluster Analysis; Drug Resistance, Multiple, Bacterial - genetics; Genetic Variation; Genotype; Geography; Humans; Microbial Sensitivity Tests; Minisatellite Repeats; Multilocus Sequence Typing; Mutation; Mycobacterium tuberculosis - classification; Mycobacterium tuberculosis - genetics; Pakistan - epidemiology; Tuberculosis, Multidrug-Resistant - epidemiology; Tuberculosis, Multidrug-Resistant - microbiology; Tuberculosis, Multidrug-Resistant - transmission
• ISSN: 1567-1348; 1567-7257
• DOI: 10.1016/j.meegid.2014.06.017

Multi-Drug Resistant Tuberculosis (MDR-TB), i.e. bacilli resistant to rifampicin (RIF) and isoniazid (INH), is a major Public Health concern in Pakistan according to WHO estimates (3.5% and 32% of new and retreated cases, respectively). Previous Pakistanis reports identified a correlation between being MDR and belonging to Beijing or EAI lineages in one study, and belonging to "H4"-Ural Euro-American sublineage in another study. In addition, MDR-TB transmission was suspected in Karachi. We tested MDR characteristics on a Punjab sample of 278 clinical isolates (without selection for Multi-Drug Resistance) including new and retreated cases collected from 2008 to 2012. All samples were characterized by a new, microbead-based method named "TB-SPRINT" (molecular diagnostic including spoligotype identification, and genetic resistance determinants to first-line anti-TB drugs RIF and INH). Isolates from 2011 to 2012 (n=100) were further analyzed using 24-loci MIRU-VNTR. We detected 8.7% MDR isolates (CI95%=[5.0; 12.5]), mainly among CAS lineage that predominates in this central-East region of Pakistan. Out of 20 MDR-TB cases, 12 different TB-SPRINT profiles were identified, limiting the suspicion of MDR-TB transmission. 24 MIRU-VNTR confirmed the unrelatedness of isolates with different TB-SPRINT profiles and discriminated 3 isolates with identical TB-SPRINT profiles. In conclusion, our study did not confirm any of the correlations between Multi-Drug Resistance and lineage or sublineage in Punjab, Pakistan. MDR-TB isolates were diverse indicating that transmission is not pervasive. TB-SPRINT proved useful as a first step for detecting MDR-TB likely transmission events, before more extensive genotyping such as 15 or 24 MIRU-VNTR and thorough epidemiological investigation.