Original Article CARBAPENEM RESISTANCE IN GRAM-NEGATIVE BACILLI ISOLATES IN AN IRANIAN 1000-BED TERTIARY HOSPITAL

Objective: Carbapenems are beta-lactamase antibiotics, presently considered as most potent agents for treatment of infections caused by Gram-negative bacilli. The aim of this study was to determine resistance of Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumonniae as prevalent nosocomial agents to commonly used antibiotics including carbapenems such as imipenem and meropenem. Methodology: A total of 202 gram-negative bacilli including K.pneumoniae, P aeruginosa and A.baumannii isolated from hospitalized patients in Milad hospital of Tehran were subject for susceptibility testing. Susceptibility testing was performed by disk diffusion and MIC methods as recommended by Clinical Laboratory Standards Institute (CLSI) Results: All isolates of K. pneumonia were susceptible to imipenem and meropenem. Resistance in non-fermenting gram-negative bacilli (NFGB) was prevalent. P.aeruginosa isolates exhibited 7.5 % and 40.2 % resistance to imipenem and meropenem respectively. The majority isolates of Acinetobacter baumannii were multi-drug resistant and resistance of this organism to imipenem and meropenem was 27.7 % and 38.5 % respectively. Conclusions: Our study revealed that in spite of resistance of K.pneumoniae to commonly used antibiotics, all isolates were susceptible to imipenem and meropeem. More than 80 % isolates of A.bammanni were resistant to commonly used antibiotics. About 40.2 % isolates of P.aeruginosa and (38.5%) isolates of A.baumannii were resistant to meropenem respectively