Detection of fluoroquinolone resistance in Mycobacterium tuberculosis clinical isolates as determined by gyrA/B gene mutation by using PCR technique

Fluoroquinolones are broad-spectrum antimicrobial agents that have been used with increasing frequency over the past decade.Fluoroquinolones have in vitro and in vivo activity against Mycobacterium tuberculosis.However, resistance to fluoroquinolones in cases of tuberculosis is not routinely assessed.Mutations in a small region of gyrA, called quinolone resistance-determining region (QRDR) and, less frequently, in gyrB are the primary mechanism of FQ resistance in M. tuberculosis.PCR-based techniques provide new possibilities for the rapid diagnosis of first- and second-line drug resistance.ResultsThere were 40 consecutive adults, who had culture confirmed pulmonary tuberculosis during the study period.Mutations were observed in the QRDRs of both gyrA and gyrB in 22 isolates (55%). Only gyrA +ve in 7(17.5%) isolates. Only gyrB +ve in 5(12.5%) isolates. Total gyrA +ve in 29(72.5%) and total gyrB +ve in 28(70%) isolates. Both gyrA and gyrB −ve in 6 (15%).ConclusionThe incidence of FO-resistant M. tuberculosis is gradually increasing to alarming levels this may be due to wide spread use of this vital groups of drugs in community-acquired pneumonia and urinary tract infections.