Antimicrobial resistance in Gram-negative bacteria from Intensive Care Units and Urology Services. A nationwide study in The Netherlands 1995-2000.

A nationwide 6-year surveillance of resistance in Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis and Pseudomonas aeruginosa from clinical specimens of patients from ten Intensive Care Units and ten Urology Services was started in 1995. MICs of amoxycillin, amoxycillin/clavulanate, trimethoprim, cotrimoxazole, norfloxacin, ciprofloxacin, cefaclor, ceftazidime, imipenem and gentamicin were determined by broth microdilution. Intensive Care Units had higher resistance levels of amoxycillin/clavulanate, cefaclor and ceftazidime (P<0.005) and lower resistance levels of nitrofurantoin, trimethoprim, cotrimoxazole and quinolones (P<0.01) than Urology Services. Changes in MIC distributions in time and development of resistant clusters were observed for nitrofurantoin (E. coli), amoxycillin (E. coli, P. mirabilis), amoxycillin/clavulanate (E. coli) and for quinolones (E. coli). The overall resistance level of ceftazidime and gentamicin was <5%, but this fluctuated with the appearance and disappearance of resistant clones in some Intensive Care Units. Quinolone resistance among P. aeruginosa from Intensive Care Units fluctuated between 7 and 14%.