title: Colonization of patients and contamination of the patients' environment by MRSA under conditions of single-room isolation.
abstract: Meticillin-resistant Staphylococcus aureus (MRSA) are endemic in hospitals worldwide and present a major concern in hospital hygiene. The aim of the present study was to investigate the relationship between patients' MRSA colonization of the body and the frequency of environmental contamination. Twenty-five MRSA-positive hospitalized surgical patients and their environment in isolation rooms were screened on four occasions over a 14-day period. Out of 1099 samples from patients, 330 (30.0%) were MRSA-positive. The median number of MRSA-positive body sites per screening decreased significantly from the 1st (3, range 1-9) to the 14th (2, range 0-9, p=0.011) day of isolation. Contamination was found in 45% of the 100 environmental sampling dates and MRSA was detected in a low proportion of the 1000 environmental surface samples: 105/1000 (10.5%). The number of positive results for each sampling date decreased from the 1st (median 1, range 0-8) to the 14th (median 0, range 0-3, p=0.21) day of isolation. The results show a very strong correlation between the number of MRSA-positive body sites of individual patients and the MRSA contamination of the patient's hospital room (r=0.700, p<0.001). Pulsed-field gel electrophoresis (PFGE) analysis demonstrated a 98% agreement between patient and environmental samples. MRSA colonization of the groin area correlates most strongly with colonization of the body and environment. Seventy-five of 240 (31%) samples taken in rooms of patients with colonization of the groin were MRSA-positive, whereas only 27 of 760 (3.6%) samples taken in rooms of patients without colonization of the groin produced positive results (odds ratio 12.3; 95% confidence interval, 7.7-20). It is concluded that MRSA patients without colonization of the groin have a relatively low risk of environmental spread of MRSA and thus a reduced risk of transmission.
authors.affiliation: Department of Hygiene, Social- and Environmental Medicine, Universitätsstr. 150, Ruhr-University Bochum, 44801 Bochum, Germany. rohr@hygiene.rub.de
authors.forename: Ute
authors.initials: U
authors.lastname: Rohr
authors.forename: Andrzej
authors.initials: A
authors.lastname: Kaminski
authors.forename: Michael
authors.initials: M
authors.lastname: Wilhelm
authors.forename: Lars
authors.initials: L
authors.lastname: Jurzik
authors.forename: Sören
authors.initials: S
authors.lastname: Gatermann
authors.forename: Gert
authors.initials: G
authors.lastname: Muhr
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002353:Carrier State / Q000382:microbiology; D003428:Cross Infection / Q000382:microbiology / Q000635:transmission*; D004197:Disease Reservoirs / Q000382:microbiology*; D004784:Environmental Monitoring; D004866:Equipment Contamination; D005260:Female; D006119:Groin / Q000382:microbiology; D006801:Humans; D017053:Infection Control; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus; D008875:Middle Aged; D016017:Odds Ratio; D010356:Patient Isolation; D013203:Staphylococcal Infections / Q000382:microbiology / Q000635:transmission*