Antimicrobial susceptibility of urinary isolates and prescribing practices of empirical antimicrobials in patients with urinary tract infection in a tertiary care hospital

Abstract

OBJECTIVE: Knowledge of local antimicrobial susceptibility is essential for prudent empiric therapy of urinary tract infection (DTI). We sought to describe antimicrobial susceptibility patterns in in-ward patients with UTI and compare it with prescribing practices. METHODS: A descriptive study was conducted at the Colombo North Teaching Hospital in consecutive patients with a positive urine culture between January 2007 and July 2008. Sensitivity testing was done using Joan Stokes method. RESULTS: Coliforms were the commonest (89.6%) isolates in 1206 specimens. The susceptibility was as follows; nitrofurantoin - 83.9% jgentamicin - 74.3%, coamoxiclav - 69.7%, cefalexin - 57.8%, norfloxacin - 57.7%, ciprofloxacin - 50%, cotrimoxazole-37.5%, ampicillin -23.3%. Clinical data analysed for 259 (females -67,95%,^12 years - 95.2%). 25.1% didn't receive empirical antimicrobials. Among the 194 who received an antimicrobial 52.1% received ciprofloxacin and 11.3% received nitrofurantoin. Concordance between the empirical antibiotic prescribed and the sensitivity of the isolated organism was seen only in 21.7%. In 16.5% urinary isolate was resistant to the empirical antibiotic and in 61.8% empirical antibiotic was not included in sensitivity testing. Overall, sensitivity of ciprofloxacin and nitrofurantoin was tested in 6.7% (susceptibility rate - 50%) and 94.3% (susceptibility rate - 83.9%), respectively. CONCLUSIONS: Coliforms were the commonest isolate irrespective of the origin, site and type of DTI. Resistance was high (£50%) to ampicillin, cotrimoxazole and ciprofloxacin. Ciprofloxacin was the most frequently prescribed empiric therapy but its sensitivity was tested in less than 10%. Despite high susceptibility rate nitrofurantoin was underutilised. There was obvious discrepancy between empirical prescribing practices and both the susceptibility pattern of isolates and sensitivity testing practices.