Evaluation of antimicrobial resistance pattern of nosocomial and community bacterial pathogens at a teaching hospital in Tehran,Iran.

Antimicrobial resistance in pathogens not only in hospitals but also in the community has become an important public health problem. The aim of this study was to determine the antimicrobial resistance patterns of predominant pathogens from hospitalized and outpatients in a university hospital in Tehran, Iran. A total of 820 samples of common Gram-negative and Gram-positive bacteria were collected from a major referral and teaching hospital affiliated to Tehran University of Medical Sciences in Iran during April 2010 to February 2011. The pattern of antibiotic resistance was determined by disk diffusion test as recommended by the Clinical Laboratory and Standards Institute (CLSI). Gram-negative bacilli were the most isolated pathogens. Acinetobacter spp. and Pseudomonas aeruginosa (P. aeruginosa) was the most antibiotic-resistant pathogens. Imipenem and piperacillin/tazobactam were the most active antimicrobials against gram-negative bacilli whereas vancomycin was the antimicrobial agent most consistently active against the Gram-positive cocci. Community-acquired organisms were more susceptible to antimicrobial drugs tested than nosocomial isolates. The rates of antibiotic resistance among isolated pathogens in this study were approximately similar to other studies. However, high rates of antibiotic resistance among Acinetobacter spp and P. aeruginosa, the most isolated pathogens, indicating that antibiotic policy is urgently needed to prevent the resistance development ago.