Characteristics of pathogens causing urinary tract infections in hospitalsin North America: Results from the SENTRY Antimicrobial Surveillance Program, 1997

Urinary tract infection (UTI) is common and involves pathogens with changin g susceptibility patterns. The SENTRY Antimicrobial Surveillance Program ev aluates international pathogen incidence patterns to defect and manage the emergence of resistant strains. We describe the antimicrobial resistance pa tterns among 1617 pathogens recovered from UTIs during the third-quarter of 1997 in North America (United States and Canada), as part of this worldwid e program. The isolates were tested against move than 50 antimicrobial agen ts (20 reported) by reference broth microdilution methods, and selected iso lates were characterized by pulsed-field gel electrophoresis (PFGE) and aut omated ribotyping. The Jive most frequently isolated species were Escherich ia coli (48.6%), Enterococcus spp. (13.7%), Klebsiella spp. (12.0%), Pseudo monas aeruginosa (6.2%), and Enterobacter spp, or Proteus mirabilis (3.8% e ach). For each nation, imipenem and cefepime produced the widest spectrum o f coverage among the beta-lactams and amikacin was best among the aminoglyc osides. For Gram-negative species, high resistance among beta-lactam antimi crobial agents was noted especially for various penicillins against E. coli (37.9% to 42.8%) and for the cephalosporins tested against enterococci (99 .4% and 100%). Approximately 7.0% of enterococci in the LISA were vancomyci n-resistant (88% with Van A). P. aeruginosa provided the most consistent le vels of resistance, but the following agents were most active against these organisms: amikacin (96.6 to 97.4% susceptible), tobramycin (89.5 to 100.0 %), piperacillin/tazobactam (89.5 to 100.0%), piperacillin (89.5 to 96.6%), imipenem (89.7 to 92.1%), cefepime (77.6 to 89.7%), and ceftazidime (82.9 to 86.2%). E. coli (2.2 to 2.7%), K. pneumoniae (6.2 to 6.4%), and a single Enterobacter cloacae strain produced extended-spectrum p-lactamases; and f ive other Enterobacter spp. were likely to have expressed chromosomally med iated (Amp C) stably derepressed cephalosporinases with associated resistan ce to ceftazidime (16.7 to 21.2% resistance). These data demonstrated that several UTI isolates in SENTRY hospitals have high levels of resistance to various classes of antimicrobial agents with little evidence of clonal diss emination. (C) 1999 Elsevier Science Inc.