frequency of pathogens and antimicrobial susceptibility of bacteria isolated from bloodstream infections

background and objectives: blood stream infections cause significant morbidity and mortality in the world. in this study, we aimed at describing the organisms responsible for septicemia in 2006-2007 and their antimicrobial susceptibility that might lead to proper selection of antimicrobial agents in hospitalized patients with suspected sepsis. materials and methods: microbiology reports of 1753 blood specimens collected from inpatients of a referral hospital in iran were retrospectively reviewed. specimen culture, bacterial identification, and disk diffusion susceptibility testing were performed according to the clinical and laboratory standards institute guidelines. data were analyzed by spss, x² test and the fisher exact test. results: coagulase-negative staphylococci accounted for most isolated bacteria (24.61%), in both genders. the second and third most frequent isolated bacteria in adults were staphylococcus aureus and stenotrophomonas maltophilia, and in children were klebsiella pneumoniae and s. aureus. among the all gram – positive cocci, vancomycin was the most effective agent. the most effective antibiotic varied among the gram-negative isolates, for example 95.65% of s. maltophilia were susceptible to co-trimoxazole, and amikacin were suitable antibiotic in 85.29% of e. coli. conclusion: as the degree of antibiotic resistance rate for blood stream pathogens is alarming, it is mandatory to monitor the susceptibility of these isolates in order to avoid inappropriate use of antibiotics in hospital wards