Multicentre surveillance of Pseudomonas aeruginosa susceptibility patterns in nosocomial infections

Objectives: To determine susceptibility rates and patterns in Pseudomonas aeruginosa strains isolated from nosocomial infections. Methods: Seven hundred and sixteen P. aeruginosa isolates from 40 different hospitals in Belgium and the Grand Duchy of Luxembourg were collected in 1999. Results: Resistance rates varied significantly between hospitals. Of the fluoroquinolones, ciprofloxacin showed least resistance (24%), levofloxacin showed 27.5% resistance and ofloxacin 37.5%. Of the aminoglycosides, amikacin was the most potent antibiotic (10.5% resistance), followed by isepamicin (12%), tobramycin (19.5%) and gentamicin (23.5%). Of the beta-lactam antibiotics, meropenem was the most active (9.5% resistance); piperacillin and piperacillin/tazobactam had, respectively, 24% and 17.5% resistance, ceftazidime 28.5%, cefepime 29.5%, ticarcillin/clavulanic acid 37% and aztreonam 55.5%. MIC distribution curves show the presence of significant subpopulations, with MICs just below breakpoint for many antibiotics. Conclusion: Resistance of P. aeruginosa to penicillins, cephalosporins, fluoroquinolones and aminoglycosides varies between hospitals, but is increasing.