Which Antibiotics Should be the First Choice for Empiric Therapy of Urinary Tract Infections

Objectives : The aims of the study were to investigate the distribution and the antibiotic resistance profiles of the microorganisms isolated from outpatients with lower urinary tract infection (UTI) during 2011-2012 period and to determine the most appropriate empirical therapy choices. Materials and Methods : Culture and susceptibility test results of 14.096 urine samples sent from outpatient clinics with presumptive lower UTI diagnosis in the last year (2011-2012) were reviewed. Excluding the duplications, totally 2005 isolates were evaluated. Culture and identification tests were done by conventional/semi-automatic and automatic methods. Antibiotic susceptibility tests were performed by Kirby-Bauer disc diffusion method according to the recommendations of CLSI (Clinical Laboratory Standarts Institute). Results : Enterobacteriaceae spp. were isolated from 82.3% of the urine samples; 1287 (64.2%) Escherichia coli and 238 (11.9%) Klebsiella pneumonia, 67 (3.3%) Pseudomonas aeruginosa was cultivated. Totally 12.9% of the samples yielded Gram-positive bacteria including 55 (2.8%) meticillin resistant coagulase negative staphylococci , 55 (2.8%) Enterococcus faecalis and 49 (2.4%) Streptococcus agalactiae . The extended spectrum beta-lactamase (ESBL) prevalence was 23.2% in E.coli and 25.4% in K.pneumoniae. Among oral antibiotics tested, nitrofurantoin (NF) had the lowest resistance rates for both Gram-positive and Gram-negative isolates with 2.7% and 12.1%, respectively.  Ampicillin for Gram-positives and Cefuroxim for Gram-negatives were other oral drugs with the lowest resistance rates with 6.3% and 25.9%, respectively. Conclusion : NF appears as the most effective oral drug for adult outpatients with UTI. Cefuroxim can be considered as the second effective choice because ampicillin-sensitive Gram-positive isolates (except Enterococcus spp ) would also be sensitive to it. NF and trimethoprim- sulfamethoxazole (TMP-SMX) is suggested as first or second choice in UTI treatment in antimicrobial therapy guidelines like Sanford and IDSA. However, TMP-SMX resistance was found 35% in our population; consequently it is not a suitable option for our patients.