Are anaerobic bacteremias decreasing? Analysis of 114,000 blood cultures over a 10-year period

Microbiology Laboratory, and Division of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Petersgraben 4, CH – 4031 Basel, Switzerland

^* To whom correspondence should be addressed. Email: rfrei{at}uhbs.ch.

	Abstract

The number of positive anaerobic blood culture results per 1,000 blood cultures performed was decreasing from 12.6 in the period of 1997-2001 to 7.0 during 2002-2006 (p <0.001) as well as the proportion of isolated anaerobic organisms compared to the number of all organisms isolated from blood cultures (7.6% to 4.3%, p <0.001) while aerobic positive cultures remained stable. In contrast, the proportion of Bacteroides fragilis group members and gram-positive cocci within the anaerobic group was increasing (26.8% to 36.7%, p=0.004 and 5.4% to 12%, p<0.001, respectively). The number of patients with anaerobic bacteremia decreased from 122 patients in 1997 to 69 in 2006.