Antimicrobial susceptibility and empirical prescribing practices in treating urinary tract infections

Abstract

INTRODUCTION: Empiric antimicrobials are recommended for urinary tract infection (UTI). Knowledge of local antimicrobial susceptibility is essential for prudent empiric therapy. Aims: To describe antimicrobial susceptibility patterns and empirical prescribing practices in adult in¬ward patients with UTI. METHODS: Data for this descriptive study was collected prospectively from consecutive adult patients with positive urine culture admitted to Colombo North Teaching Hospital. Sensitivity testing was done using Joan Stokes method. RESULTS: Among 745 patients, 441 (59.2%] were females. Mean (SD) age of the study population was 48.2 (19) years. Coliforms were the commonest (85.6%) isolates followed by Streptococcus spp., Candida spp., Staphylococcus spp., and Pseudomonas spp.. Susceptibility of bacteria to antimicrobials was as follows; nitrofurantoin- 76.8%, gentamicin- 62.7%, cefuroxime- 46.3%, co-trimoxazole- 44.1%, norfloxacin-43.6%, cefalexin- 37.6%, ciprofloxacin- 37.3%, co-amoxiclav- 20.7%, ampiciUin- 17.6%. 381(51.1%) received empirical antimicrobial therapy. 75 received more than one antimicrobial. Ciprofloxacin was the most frequently prescribed empirical antimicrobial (208/381; 54.6%). Nitrofurantoin was prescribed in only 9.2%. Concordance between the empirical antimicrobial prescribed and the sensitivity of the isolated organism was seen only in 25.7%. In 29.6%, urinary isolate was resistant to the empirical antimicrobial and in 44.7% the prescribed empirical antimicrobial was not included in sensitivity testing. CONCLUSIONS: Susceptibility was low (<50%) to the first line antimicrobials other than nitrofurantoin and gentamicin. Ciprofloxacin was the most frequently prescribed empiric therapy even though susceptibility to it was low. Despite high susceptibility nitrofurantoin was underutilized. There was obvious discrepancy between empirical prescribing practices and susceptibility pattern of isolates.