Changing pattern of antibiotic resistance of bacterias isolated from urine cultures in the last four years

Objective: The aim of this study is to evaluate the changing pattern of antibiotic resistance of gram negative rods isolated from urine samples of patients with urinary tract infection (UTI) according to years.

Materials and methods: Between January 2005 and April 2008, we evaluated a total of 3.739 urine samples which bacterial isolates from outpatients (n: 2.850, 75.3%) and inpatient clinics (n: 924, 24.7%), retrospectively. Resistance of amoxicillin-clavulanate, cefozoline, cefotaxime, cefoperazone-sulbactam, ceftazidime, aztreonam, amikacin, imipenem-cilastatin, trimethoprim-sulfamethoxazole, ciprofloxacin, meropenem and piperaciline-tazobactam to gram negative rods were analyzed by using the chi-square test.

Results: Our results indicate that E. coli (n: 1892, 67.2%; n: 458, 49.6%), P. mirabilis (n: 212, 7.5%; n: 40, 4.3%) K. pneumoniae (n: 109, 3.9%; n: 49, 5.3%) and P. aeruginosa (n: 90, 3.2%; n: 97, 10.5%) are the most common organisms causing UTI in outpatient and inpatient groups, respectively. Although, the resistance of E. coli to amoxicillin-clavulanic acid and trimethoprim-sulfamethoxazole in outpatients is decreasing with respect to years (p<0.05), the resistance of E. coli to ciprofloxacin in inpatients is not significantly changed (mean, 15.4%). The lowest resistance was observed in imipenem-cilastatin and amikacin with 1.2% and 3.6% among inpatients, respectively. Ciprofloxacin resistance in inpatients was significantly high with a rate of 40.2% in four years. Amikacin and piperaciline-tazobactam have the most anti-pseudomonal efficiency with 89.1% and 87.6%, respectively.

Conclusion: The resistance of antibiotics to gram negative rods is a dynamic process. The major factor in the development of antibiotic resistance may be the extensive use of antibiotics. Antibiotic usage and resistance should be followed up and antibiotic usage policy should be determined nationally and locally for each hospital.