223. The risk factors for blood culture contamination in Emergency department
Session: Poster Abstract Session: Diagnostic Microbiology
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C

Blood culture is irreplaceable for the detection of life threatening bloodstream infection. Blood culture contamination waste medical resources unnecessarily. In an emergency department (ED) setting in Japan, we aimed to identify risk factors for blood culture contamination with a focus on clinical characteristics of the patient(pt), and hospital-and physician-related factors.


A case-control study was conducted among adult patients visiting the ED at a community hospital in Tokyo, Japan. Subjects were selected among 13,582 pts that underwent 2 sets of blood cultures between 2003 and 2012. In total, 292 (2.1%) pts had a contaminated blood culture. Among the 11,968 blood culture negative pts, we randomly selected 300 pts to serve as the control group. The electronic medical records were accessed to obtain on clinical characteristics of the patient and hospital/physician-related characteristics. Multivariate logistic regression was used to evaluate the indeoendent contribution of these variables on risk of contamination.


Of the 592 cases and controls, 298 (50.3%) were male and the mean age was 66.9 years (range 17-106, SD 20.6). In the bivariate analysis of patient characteristics, several factors appeared associated with contamination, but the adjusted analysis showed statistically significant independent effects only for age, and lactate dehydrogenase, and results were suggestive for glucose level. In a multivariate analysis focused on hospital/physician-related factors, arrival time, time from ED arrival to taking blood culture and season appeared to be associated with contamination. The final logistic regression analysis considering both patient and hospital/physician-related characteristics in a single multivariate model showed contamination to be independently associated with age (OR = 1.03, 95%CI 1.02-1.04, p<0.001), time to taking blood culture (OR = 0.964, 95% CI 0.93-0.95, p=0.025), and summer season (versus winter: OR = 2.00, 95%CI 1.20-3.31).


Our study found older age, shouter time from ED arrival to taking blood culture, and the summer season to be independent risk factors for contamination. Careful consideration of these identified factors when taking blood cultures may help to reduce the frequency of contamination and its associated costs in the future.

Akira Mikami, MD1, Yoichiro Natori, MD2, Yu Kurata, MD3, Sachiko Ohde, Ed.M4, Gautam. A Deshpande, MD4,5, Kevin Urayama, PhD4, Toshiaki Mochizuki, MD1, Norio Otani, MD1 and Shinichi Ishimatsu, PhD1, (1)Department of Emergency & Critical Care Medicine, St. Luke’s International Hospital, Tokyo, Japan, (2)Division of Infectious Diseases, St. Luke's International Hospital, Tokyo, Japan, (3)Department of Educational Training, St. Luke’s International Hospital, Tokyo, Japan, (4)Center for Clinical Epidemiology, St. Luke's Life Science Institute, Tokyo, Japan, (5)Department of Internal Medicine, University of Hawaii, Honolulu, HI


A. Mikami, None

Y. Natori, None

Y. Kurata, None

S. Ohde, None

G. A. Deshpande, None

K. Urayama, None

T. Mochizuki, None

N. Otani, None

S. Ishimatsu, None

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