OBJECTIVES: To obtain information on the microbiology workload, etiology and antimicrobial susceptibility of urinary tract infection (UTI) pathogens isolated in European hospitals. MATERIALS AND METHODS: We collected data available in the microbiology units of a large sample of European hospitals regarding the laboratory workload, diagnostic criteria, and etiology and antimicrobial resistance of the urinary isolates collected on one day (the study day). RESULTS: Data were received from a total of 228 hospitals from 29 European countries. The average rate of urine samples cultured per 1000 admissions in 1999 was 324. The criteria to consider a positive urine culture as significant were quite variable; > or =10(4) colony-forming units (CFU)/mL for bacteria or > or =10(3) CFU/mL in the case of yeasts were the most used cut-off points. On the study day, a total of 607 micro-organisms from 522 patients with nosocomial UTI were isolated. The six most commonly isolated micro-organisms were, in decreasing order: Escherichia coli (35.6%), Enterococci (15.8%), Candida (9.4%), Klebsiella (8.3%), Proteus (7.9%) and Pseudomonas aeruginosa (6.9%). Pseudomonas was isolated more frequently in non-EU countries. The study data reveal high rates of antimicrobial resistance in UTI pathogens, especially in non-EU countries, where Pseudomonas aeruginosa presented rates of aminoglycoside resistance as high as 72% to gentamicin, 69.2% to tobramycin and 40% to amikacin. CONCLUSIONS: Nosocomial UTI accounts for an important proportion of the workload in microbiology laboratories. A consensus on the practice and interpretation of urine cultures in Europe is needed. The levels and patterns of resistance of UTI pathogens must be a serious cause for concern and a clear reason for stricter guidelines and regulations in antimicrobial policy.