Bacteriological Profile and Antimicrobial Resistance of Blood Culture Isolates

Abstract

Background: Bloodstream infection (BSI) is an important cause of mortality and morbidity and among the most common health-care associated infections. In this study we described the frequency of occurrence and antimicrobial susceptibility patterns of nosocomial and community-acquired BSI isolates from a teaching hospital in Tehran, Iran. Patients and methods: This cross-sectional study was conducted in 850-bed Rasul Akram university hospital from April 2006 to April 2007. All patients with a positive blood culture were enrolled. Antimicrobial susceptibility testing was performed with disk diffusion and E-test MIC. Results: During the study period, 456 isolates were obtained from blood cultures, from a total of 8818 collected sets, among which 291were felt to represent true bacteremia and 98 were nosocomial. Acinetobacter spp. were the most : frequently isolated agents in the hospital and community acquired BSIs (32%), followed by Escherichia coli (13.7%) and Klebsiella spp. (12%). The most effective antibiotics for gram-negative and gram-positive bacteria were ciprofloxacin (13% resistance rate) and vancomycin and oxacillin (with 13% resistance rate), respectively. Analysis of antibiotic resistance pattern showed that 20.43% of Acinetobacter spp. and 15.4% of Pseudomonas aeruginosa were multi drug resistant (MDR), while 48.7% of Klebsiella spp were ESBL-producing isolates and 15% of Staphylococcus aureus were oxacillin-resistant. Conclusion: We did not observe any vancomycin-resistant strains among isolates of S. aureus. Rifampin and ciprofloxacin showed good activity against most of gram-positive and gram-negative organisms, respectively. Carbapenems (imipenem and meropenem) were highly active against strains of Enterobacteriaceae (E. coli, Klebsiella) that showed resistance to third generation of cephalosporines.