GyrA gene mutations of M. tuberculosis and previous use of ciprofloxacin and ofloxacin in quinolone resistance

This study assesed quinolone resistance in MDR and non-MDR cases. It also analyzed the duration of ciprofloxacin (Cfx) and ofloxacin (Ofx) use in resistance and sensitive isolates. The position and type of gyrA gene mutations in quinolone resistant isolates were also evaluated. Methods: This was a combined analytic observation with cross-sectional timed and biomolecular qualitative study using a total of 35 M. tuberculosis clinical isolates between 2007 and 2009. The susceptibilities of isolates to Cfx and Ofx were determined by using MIC methode on LJ medium. Amplification of gyrA gene was done using PCR with touch-down program to all resistant-isolates. PCR product was then futher used as a template for DNA sequencing. Results: Quinolone resistance among the MDR isolates was significantly higher than non-MDR (p=0,008). Compared to sensitive isolates, the duration of previously used Cfx was 10,46 weeks longer in resistant isolates (p=0,021). There was no significant difference in the duration of Ofx between resistant and sensitive isolates with 22,75 weeks and 17,02 weeks of mean rank respectively (p=0,218). Quinolone resistance exihibited point mutations at Asp89Val (16.7%), Asp94Gly (50%), Asp94Ala (16.7%), Asp94Asn (16.7%), Ser95Thr (83.3%), Ser95Asn (16.7%). Conclusion: Quinolone resistance among MDR isolates is high in rate. All of quinolone-resistant isolates shows missense mutations on gyrA gene with high-level resistance. Cfx has been used more frequently and longer than Ofx in MDR and non-MDR cases