Prevalence of Ciprofloxacin Resistance Among Gram-Negative Bacilli in a Tertiary Care Hospital

Background: Bacterial resistance to antibiotics is a growing therapeutic problem, both in the community and the hospitals, which involves all the antibiotics including fluoroquinolones. The decreased susceptibility to fluoroquinolones arises mainly due to single-step mutations in the gyrA and the parC genes, which encode the fluoroquinolones targets, the topoisomerase enzymes, thus conferring cross-resistance to the fluoroquinolones. In 1998, some mobile elements with a potential for the horizontal transfer of the quinolone resistance genes were described. The loci which are responsible for this plasmid-mediated quinolone resistance, which have been designated as qnr A, qnr B and qnr S, have been identified in the Enterobacteriaceae species. Aim: This study was undertaken to evaluate the susceptibility pattern of the isolates to various antibiotics and to know the prevalence rate of ciprofloxacin resistance in our hospital. Materials & Methods: A total of 734 gram-negative bacilli (GNB) which were isolated from various clinical samples over a period of six months, were subjected to antibiotic susceptibility testing. Isolates with resistance or with a decreased susceptibility to ciprofloxacin (<= 20 mm) were then screened for their minimum inhibitory concentration (MIC) by using the E-test. Results: Out of 734 GNB, 235 (32%) isolates were resistant to ciprofloxacin. The MIC of these isolates ranged from 4 to > 32 mu g/ml. Conclusion: The resistance rate to ciprofloxacin was 32% in our study. Most of the ciprofloxacin resistant isolates were from urinary tract infections (UTI). The ciprofloxacin resistance was also closely associated with multi-drug resistance, thus limiting the treatment options. Ciprofloxacin resistance can be used as a general surrogate marker of multidrug resistance, thus limiting the already restricted treatment options. The considerably high MIC values for ciprofloxacin in this study reflected the extent of the treatment problems for these resistant isolates and a need for the continuous evaluation of the commonly used antibiotics.