Antibiotic coresistance among extended-spectrum beta lactamase-producing urinary isolates in a tertiary medical center: A prospective study

Aim: Urinary tract infections are among the most common infections encountered in clinical practice. Study was conducted to detect extended-spectrum beta lactamase (ESBL) type of resistance in urinary isolates in North Eastern Region of India. Materials and Methods: Midstream urine sample was collected from 200 patients clinically suspected to be suffering from urinary tract infections and attending Outpatients Departments and different wards in Assam Medical College and Hospital Dibrugarh, a tertiary teaching hospital from September 2007 to August 2008. The patients who did not have a course of antibiotic before 15 days of study were included, whereas patients with known history of diabetes, thyroid disorders, renal disease, and hypertension were excluded from the study group. Urine samples were cultured as per guidelines and ESBL detected by double disc diffusion tests. Statistical Analysis: Test of proportion and two-tailed Z test were used for data analysis. Results: In all, 171 isolates of Gram-negative bacilli were detected of which 42 isolates produced ESBL. So the detection rate of ESBL in the study was 24.56%. The ESBL-producing isolates were 19 (28.78%) in males and 23 (21.9%) in females, and this difference was not found to be significant ( P > 0.05). In 97.61% of isolates, associated resistance was observed for ampicillin and cotrimoxazole. Ciprofloxacin and gatifloxacin showed coresistance of 69.04% and 71.42%, respectively. Associated resistance for amoxycillin/clavulanic acid and piperacillin/tazobactum was 38.09% and 35.71%. All the isolates of Enterobacteriaceae producing ESBL were 100% sensitive to imipenem. Conclusion: These data provided the much needed information on the prevalence of antimicrobial resistance among pathogens causing urinary tract infections. Results seem helpful in providing useful guidelines in choosing an effective antibiotic in cases with urinary tract infection and also initiating therapy in antimicrobial-resistant strains.