title: Bacteraemia caused by hospital-type micro-organisms during hospital stay.
abstract: A sharp transition between community-type and hospital-type pathogens at the second or third day of hospital stay is often assumed. This study aimed to test whether such a threshold phenomenon exists for bloodstream infections and to examine the relationship between the proportion of infections caused by hospital-type pathogens and length of stay in the hospital. Blood stream infections were studied in a referral and a university hospital in west Denmark, and a university hospital in central Israel during three study periods (1994-1996, 1992-1995, 1989-1995 in the three hospitals respectively). No threshold effect at 2-3 days stay in the hospital could be demonstrated. However the percentage of Pseudomonas aeruginosa bloodstream infections increased constantly in the three hospitals from 1%, 1% and 7% during the first 2 days to 7%, 4%, and 14% during the third week of hospital stay (P<0.01 for all three comparisons-chi(2)for linear trends). For Candida sp. the increase was from 0%, 2%, 1% during the first 2 days to 3%, 4%, and 9% during the third week, P<0.05. Methicillin-resistant Staphylococcus aureus in Israel increased from 26% of the total number of S. aureus during the first 2 days to 69% during the third week, P<0.0001. For penicillin-resistant S. aureus in Denmark, the percentages were 84% and 100%, P<0.05.The percentage of infections caused by hospital-type pathogens increased almost linearly during the first 3 weeks of hospital stay, with no threshold effect. This trend should be taken into account when prescribing empirical therapy for nosocomial infections.
authors.affiliation: Department of Medicine, Infectious Diseases Unit, Microbiology Laboratory, Rabin Medical Center, Beilinson Campus, Petah-Tiqva, Israel.
authors.forename: L
authors.initials: L
authors.lastname: Leibovici
authors.forename: H
authors.initials: H
authors.lastname: Schønheyder
authors.forename: S D
authors.initials: SD
authors.lastname: Pitlik
authors.forename: Z
authors.initials: Z
authors.lastname: Samra
authors.forename: J K
authors.initials: JK
authors.lastname: Møller
mesh_terms: D016470:Bacteremia / Q000209:etiology / Q000382:microbiology*; D002175:Candida / Q000302:isolation & purification*; D003428:Cross Infection / Q000209:etiology / Q000382:microbiology*; D003718:Denmark; D004352:Drug Resistance, Microbial; D006801:Humans; D007557:Israel; D007709:Klebsiella / Q000302:isolation & purification*; D007902:Length of Stay; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification*; D013211:Staphylococcus aureus / Q000302:isolation & purification*; D013997:Time Factors