Trends in Antibiotic Resistance Pattern among Escherichia coli Isolates from Patients with Urinary Tract Infection in Tertiary Care Hospital, Bellary

To study the prevalence rate and to determine the resistance pattern among Escherichia coli isolates to commonly used antibiotics from patients having Urinary tract infections (UTI) and to determine Extended spectrum beta lactamase (ESBL) producers among them and their sensitivity pattern. Out of 580 urine samples processed from patients with urinary tract infection during a study period of six months, 303 samples yielded growth on culture out of which Escherichia coli (E. coli) was found to be the commonest isolate accounting for 39.6% (n=120), whereas 183 samples yielded bacteria and fungi other than E. coli. All the E. coli isolates were subjected for antibiotic sensitivity testing by Kirby Bauer disk diffusion method on Muller Hinton Agar in accordance with CLSI guidelines. Out of the 12 antibiotics tested against E. coli isolates, amoxycillin (100%) , fluoroquinolones [ciprofloxacin (95.8%), norfloxacin (91.7%), ofloxacin (96.7%)], third generation cephalosporins [ceftazidime (91.7%), ceftriaxone (94.2%), cefotaxime (97.5%)], showed the highest resistance, followed by cotrimoxazole (66.7%), piperacillin-tazobactum (55.8%) and amikacin (39.2%), while least resistance was shown by imipenem (5.9%) and nitrofurantoin (21.7%). Moreover our study identified 26 E. coli isolates (21.6%) to be extended spectrum beta lactamases (ESBL) producers by Double disc diffusion synergy test (DDST). All ESBL E. coli were resistant to ceftazidime, cotrimoxazole and amoxicillin whereas sensitive to imipenem. Highest number of ESBL producers was detected by ceftazidime. E. coli were found to be the commonest causative agent of UTI in our study showing co-resistance to many classes of antibiotics. The study concluded that nitrofurantoin could be recommended for empirical therapy in UTI patients in our region.