INTRODUCTION: Urinary tract infections (UTIs) are more common in people presenting predisposing factors (urinary stones, malformations, diabetes, pregnancy). Choosing the proper medication is very important for an efficient treatment and to prevent recurrencies.

MATERIAL AND METHODS: We selected 566 hospitalized and outpatients in the high risk group and 1265 patients in the control group. Urine samples were collected in sterile recipients and cultivated on proper culture media. Antibiotic susceptibility testing (AST) was performed for all significant isolates.

RESULTS: Amongst the patients with predisposing factors we found the following proportions of UTI: diabetic patients - 38.5%, urolithiasis - 25.2%, urinary tract malformations - 23.85%, and pregnancy - 18.5% of the cases. The most frequent isolated strain was Escherichia coli in each group. Positive cultivation results were more frequent in women. We found multidrug resistant bacteria in every patient group (except the pregnant women), especially ESBL-producing E. coli. In the majority of cases enterobacteria presented good susceptibility to fluoroquinolones, cephalosporins and

gentamycin.

CONCLUSIONS: In high-risk group patients the UTI are common and resistant strains are often present. Positive results were more frequent in women. The optimal treatment requires the antibiotic susceptibility testing for all isolates.

Keywords: antibiotics, bacteria, urinary tract infection