Nosocomial Infections Caused by Drug-Resistant Bacteria in a Referral University Hospital, Tehran, Iran

Background: The emergence of antimicrobial-resistant pathogens associated with hospital-acquired infections (HAIs) is a major public health problem worldwide. Although being drug resistance is common in some countries and rare in others, the extent of this condition is not precisely known in most parts of Iran. Materials and Methods: Clinical specimens from patients who had been in the hospital for at least 48 hours were included in this study. The pattern of antibiotic resistance was determined by disk diffusion method as recommended by the Clinical Laboratory and Standards Institute (CLSI). Results: Of 11164 patients that were investigated, 369 (3.3%) had nosocomial infections. The most frequently isolated organisms from all sites of infections were Acinetobacter species (14.2%), Escherichia coli (13.7%) and Pseudomonas aeruginosa (9.9%). Among the Gram-negative bacilli, Acinetobacter spp was mostly resistant to ciprofloxacin, ceftriaxon, co-trimoxazole and centamicin, while P. aeruginosa was frequently resistant to ampicillin/sulbactam (87%). Imipenem and piperacillin/tazobactam were the most active antimicrobials against gram-negative microorganisms whereas vancomycin was the antimicrobial agent most consistently active against the Gram-positive cocci. Conclusions: This study highlights the importance of antimicrobial-resistant pathogens associated with nosocomial infection in Tehran, Iran. Using proper diagnostic criteria as well as administering more effective treatment may limit the frequency of drug-resistant bacteria associated with HAIs.