Mycobacterium tuberculosis isolate with a distinct genomic identity overexpresses a tap-like efflux pump

Background: One mechanism proposed for drug resistance in Mycobacterium tuberculosis (MTB) is by efflux of the drugs by membrane located pumps. We report a novel and definite association between drug resistance and transcription levels of a tap-like pump (Rv1258c) in a multi-drug resistant MTB patient isolate (ICC154) which possesses a unique genotypic signature. Materials and Methods: The isolate ICC154 was tested for drug sensitivity. Over-expression of Rv1258c as a function of drug pressure was analyzed by RT-PCR and the strain was typed using fluorescent amplified fragment length polymorphism (FAFLP). Result: In the presence of rifampicin and ofloxacin, this isolate shows increased transcription of the gene Rv1258c. Genotypic fingerprinting revealed the presence of unique FAFLP markers. Conclusion: A clear association between drug resistance and overexpression of an efflux protein is evident from our studies. The presence of specific markers has implications in rapid identification of MDR clinical isolates and consequent disease management.