[Profile of bacterial isolates and antimicrobial susceptibility: Multicenter study using a one-day cut-off]

The frequency and antimicrobial susceptibility of bacterial isolates from the largest clinical samples collected in 19 Spanish hospitals were studied. A total of 523 strains were identified and grouped by sample. Blood stream: Staphylococcus coagulase-negative (41%) and Escherichia coli (19.7%); oxacillin resistance occurred in 44% of coagulase-negative strains, strains which were also resistant to nonbetalactam agents. All antimicrobial agents tested had good activity against E. coli, with the exception of penicillins (25 to 33% susceptible). Urine: E. coli (59.1%) and Enterococcus faecalis (15%); aminoglycosides and third generation cephalosporins were the most active compounds against E. coli, whereas penicillins and cotrimoxazole were the least active. E. faecalis isolates showed low rates of resistance to the antibiotics tested and no glycopeptide-resistant strains were detected. Skin and soft tissues: Staphylococcus aureus (24.1%), Pseudomonas aeruginosa (17.7.%); oxacillin resistance occurred in 15.8% of S. aureus strains and co-resistance to nonbetalactam agents was frequently observed among these strains. Ceftazidime susceptibility was elevated among P. aeruginosa (76.9%) and the most active agents were aminoglycosides (100% susceptibility). Lower respiratory tract: P. aeruginosa (21.4%) and Haemophilus influenzae (15.5%). Aminoglycosides (88.8 to 94.4%) and ceftazidime (72%) presented the highest susceptibility rates in P. aeruginosa. All the agents tested were very active against H. influenzae (89% susceptibility). Among Gram-positive cocci, no vancomycin and/or teicoplanin-resistant strains were detected.