Indagine epidemiologica locale dell’eziologia delle infezioni delle vie urinarie (IVU) nosocomiali e comunitarie e dell’antibiotico-sensibilità degli uropatogeni.

Background: Urinary tract infections (UTIs) are common infectious diseases that can be associated with substantial morbidity. During the last decade, resistance to ampicillin and co-trimoxazole has increased in Escherichia coli, the most common uropathogen, and recent reports have shown increasing resistance even to fluoroquinolones. The aim of this local surveillance study was to determine the distribution of bacterial strains isolated from outpatients and inpatients with UTIs and antibiotic susceptibility patterns to antimicrobial agents currently used in the treatment of pathogens causing these infections. Materials and methods: Between January and March 2006 a total of 1596 urine specimens, 968 from outpatients and 628 from inpatients, respectively, were recovered. Urinary pathogens isolated were 235, identification and antimicrobial susceptibility testing were performed by Vitek II.The following antimicrobial agents were tested: ampicillin, amoxicillin-clavulanic acid, ceftazidime, imipenem, co-trimoxazole, ciprofloxacin, gentamicin and nitrofurantoin. E test® method were used to study the production of extended spectrum beta-lactamases (ESBL). Results:The most frequent pathogen found was Escherichia coli (68.5%), followed by Klebsiella spp. (8.5%), Proteus mirabilis (7.6%), and Enterococcus spp. (6%). E. coli resistance rates less than 10% was observed for ceftazidime, imipenem and nitrofurantoin. In strains isolated from outpatients resistance to ampicillin and trimethoprim-sulfamethoxazole was 37% and 19%, respectively, and resistance to fluoroquinolones was about 20%. Resistance rates of E. coli was significantly higher in complicated nosocomial-acquired infection: ampicillin 53.6%, cotrimossazole 35.7% and ciprofloxacin 33.9%. ESBL producer strains were 7 E.coli (4.3%) and 6 Proteus spp. (33%). Conclusions: This study confirmed that E. coli and other Enterobacteriaceae are the predominant bacterial pathogens envolved in UTIs. Currently, the empirical use of co-trimoxazole and ampicillin is not recommended. Because of the increase in fluoroquinolones resistance among uropathogens patients who can benefit from these antimicrobial agents must be selected. Third-generation cephalosporins still have high sensitivity rates (although the the emergence of extended-spectrum beta-lactamase-producing enterobacterial should be taken into account). Urine culture and antimicrobial susceptibility testing is the “gold standard” for diagnosis of UTI and selection of appropriate treatment.