Antimicrobial susceptibility of imipenem-resistant Pseudomonas aeruginosa

1Institute for Medical Microbiology and Virology, Universitätsklinikum Düsseldorf, Universitätsstraße 1, Geb. 22.21, 40225 Düsseldorf, Germany; 2Eijkman-Winkler Institute for Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands Sir, In a recent leading article by Giamarellou,1 the prescribing guidelines for Pseudomonas aeruginosa infections were discussed. It was stated that the anti-pseudomonal drugs available for the clinician include the aminoglycosides, ureidopenicillins, ceftazidime, the carbapenems and ciprofloxacin. Given the propensity for this organism to become drug resistant, a worrying question for the clinician arises: what alternatives exist if one of these major anti-pseudomonal drugs fails? Recent surveillance studies with P. aeruginosa have not differentiated between imipenem-susceptible and -resistant isolates.2,3 In the present study, we investigated the antibiotic susceptibility of 86 unrelated imipenem-resistant P. aeruginosa strains, by broth microdilution using NCCLS recommendations.4 These organisms were isolated in 1998–1999 from European hospitals as part of the SENTRY antimicrobial surveillance programme. We also tested these isolates against some of the new fluoroquinolones. The MIC data are summarized in Table 1.