Carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter baumannii isolates in an Iranian 1,000-bed hospital

Abstract number: 1733_860

Rahbar M., Islami P., Molanaee S., Deldari M.

Objective: Carbapenems, including imipenem and meropenem, are b-lactam antibiotics which widely are used recently in our country. The aim of this study was to determine resistance of P. aeruginosa, A. baumannii and Klebsiella pneumoniae to carbapenems in our hospital.

Methods: From April 2006 to October 2006 one hundred nosocomial isolates including 29 strains of P. aeruginosa, 27 Acinetobacter baumannii and 44 isolates of Klebsiella pneumoniae were collected from specimens obtained from hospitalised patients. The MIC f of meropenem for all isolates was determined by E-test (AB/Bio disk Sweden). Susceptibility to other antibiotics including Pipracillin/Tazobactam, Cefepime Ciprofloxacin, Amikacin, Imipenem and Ceftazidim were performed by disk diffusion method as recommended by Clinical Laboratory Standards institute (CLSI).

Results: MIC for meropenem by E-test ranged from 0.25 mg/mL to 32 mg/mL. Of 29 isolates of P. aeruginosa, 7 (24%) were resistant to meropenem (MIC > 32 mg/mL). These isolates also were resistant to imipenem. In Acinetobacter baumannii, of 27 isolates 8 (27%) were resistant to meropenem. All isolates of K. pneumoniae were susceptible to meropenem and imipenem. Only one strain had intermediate resistance (MIC = 6 mg/mL). Resistance to other tested antibiotics was very high and more than 80% of organisms were resistant to Piperacillin/Tazobactam, Cefepime, Ciprofloxacin, Amikacin, and Ceftazidim. All isolates of Klebsiella pneumoniae were resistant to Ceftazidim.

Conclusion: These studies showed that nearly one fourth of non-fermenter tested organisms in our study were resistant to carbapenems. However resistance of K. pneumoniae to carbapenem is not a serious problem already in our hospital.