Staphylococcus aureus colonization at ICU admission as a risk factor for developing S. aureus ICU pneumonia.
OBJECTIVE
To quantify the incidence of intensive care unit (ICU)-acquired pneumonia caused by Staphylococcus aureus (S. aureus) and its association with S. aureus colonization at ICU admission.


METHODS
This was a post-hoc analysis of two cohort studies in critically ill patients. The primary outcome was the incidence of microbiologically confirmed S. aureus ICU-acquired pneumonia. Incidences of S. aureus ICU pneumonia and associations with S. aureus colonization at ICU admission were determined using competing risks analyses. In all ICUs, patients were screened for respiratory tract S. aureus carriage on admission as part of infection control policies. Pooling of data was not deemed possible because of heterogeneity in baseline differences in patient population.


RESULTS
The two cohort studies contained data of 9156 ICU patients. The average carriage rate of S. aureus among screened patients was 12.7%. In total, 1185 (12.9%) patients developed ICU pneumonia. Incidences of S. aureus ICU pneumonia were 1.33% and 1.08% in cohorts 1 and 2, respectively. After accounting for competing events, the adjusted subdistribution hazard ratio (SHR) of S. aureus colonization at admission for developing S. aureus ICU pneumonia was 9.55 (95% CI 5.31-17.18) in cohort 1 and 14.54 (95% CI 7.24-29.21) in cohort 2.


CONCLUSIONS
The overall cumulative incidence of S. aureus ICU pneumonia in these ICUs was low. Patients colonized with S. aureus at ICU admission had an up to 15 times increased risk for developing this outcome compared with non-colonized patients.
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, Netherlands. Electronic address: f.p.paling@umcutrecht.nl.
F P
FP
Paling
Institute for Medical Biometry and Statistics, University Medical Center Freiburg, Freiburg, Germany.
M
M
Wolkewitz
Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, Netherlands.
L G M
LGM
Bode
Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, Netherlands; Department of Intensive Care Medicine, University Medical Center Utrecht, Utrecht, Netherlands.
P M C
PMC
Klein Klouwenberg
Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, Netherlands; Department of Intensive Care Medicine, University Medical Center Utrecht, Utrecht, Netherlands.
D S Y
DSY
Ong
Department of Intensive Care Medicine, University Hospital of Ghent, Ghent, Belgium.
P
P
Depuydt
Department of Intensive Care Medicine, University Hospital of Ghent, Ghent, Belgium.
L
L
de Bus
AstraZeneca LP, Gaithersburg, MD, USA.
F
F
Sifakis
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, Netherlands; Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, Netherlands.
M J M
MJM
Bonten
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, Netherlands.
J A J W
JAJW
Kluytmans
D000328:Adult; D000368:Aged; D002353:Carrier State; D003428:Cross Infection / Q000382:microbiology*; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011023:Pneumonia, Staphylococcal / Q000382:microbiology*; D012307:Risk Factors; D013211:Staphylococcus aureus / Q000302:isolation & purification*
Colonization; Intensive care; Pneumonia; S. aureus; VAP