Background: Blood culture is the definitive method for the diagnosis and treatment of bacteremia and fungemia. Analysis of blood cultures positive for pathogenic species and trends in antimicrobial susceptibility can help delineate appropriate and experimental treatment strategies. In this study, we investigated the incidence of pathogenic species and trends in antimicrobial susceptibility in blood cultures collected from 2003 to 2007 to help clinicians to determine the best methods of diagnosis and treatment. Changes between previously published analyses and this study were also investigated.

Methods: Five-year blood culture results obtained at Kyung Hee University Hospital between 2003 and 2007 were analyzed to determine the bacterial and fungal species present and the antimicrobial susceptibility of the isolates. Antimicrobial susceptibility was tested by the broth microdilution method and the CLSI disk diffusion method.

Results: Among the 66,437 blood cultures, 5,645 were positive. Of the positive blood cultures, 59.8% were positive for aerobic and facultative anaerobic gram-positive cocci. Coagulase-negative staphylococci (CoNS) were frequently isolated. The numbers of anaerobic species and fungi decreased over the years.

Conclusion: CoNS were the microorganisms most commonly isolated from blood cultures at Kyung Hee University Hospital. The number of cultures positive for fungi was higher than that reported in previous studies, but the absolute isolation rate over five years decreased. Anaerobic species were much less frequently isolated than reported for other hospitals. (Korean J Clin Microbiol 2009;12:163-168)