Active surveillance to determine the impact of methicillin-resistant Staphylococcus aureus colonization on patients in intensive care units of a Veterans Affairs Medical Center.
OBJECTIVE
The impact of methicillin-resistant Staphylococcus aureus (MRSA) colonization on mortality has not been well characterized. We sought to describe the impact of MRSA colonization on patients admitted to intensive care units (ICUs) in the Birmingham Veterans Affairs Medical Center (VAMC).


METHODS
We conducted a retrospective cohort study of ICU patients at the Birmingham VAMC during 2005 to evaluate the predictors of MRSA colonization and determine its effect on clinical outcomes. Surveillance cultures for MRSA were performed on admission to the ICU and weekly thereafter. Clinical findings, the incidence of MRSA infection, and mortality within 3 months after ICU admission were recorded. Predictors of mortality and S. aureus colonization were determined using multivariable models.


RESULTS
S. aureus colonization was present in 97 (23.3%) of 416 patients screened, of whom 67 (16.1%) were colonized with methicillin-susceptible S. aureus (MSSA) and 30 (7.2%) with MRSA. All-cause mortality at 3 months among MRSA-colonized patients was significantly greater than that among MSSA-colonized patients (46.7% vs 19.4%; P = .009). MRSA colonization was an independent predictor of death (adjusted odds ratio [OR], 3.7 [95% confidence interval [CI], 1.5-8.9]; P = .003) and onset of MRSA infection after hospital discharge (adjusted OR, 7.6 [95% CI, 2.48-23.2]; P < .001). Risk factors for MRSA colonization included recent antibiotic use (adjusted OR, 4.8 [95% CI, 1.9-12.2]; P = .001) and dialysis (adjusted OR, 18.9 [95% CI, 2.1-167.8]; P = .008).


CONCLUSIONS
Among ICU patients, MRSA colonization is associated with subsequent MRSA infection and an all-cause mortality that is greater than that for MSSA colonization. Active surveillance for MRSA colonization may identify individuals at risk for these adverse outcomes. Prospective studies of outcomes in MRSA-colonized patients may better define the role of programs for active MRSA surveillance.
Patel
Mukesh
M
Birmingham Veterans Affairs Medical Center, Birmingham, Alabama, USA. mukesh@uab.edu
Weinheimer
Jeffrey D
JD
Waites
Ken B
KB
Baddley
John W
JW
D000368:Aged; D000407:Alabama / Q000453:epidemiology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D015331:Cohort Studies; D005260:Female; D017052:Hospital Mortality; D006787:Hospitals, Veterans / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D008297:Male; D008712:Methicillin / Q000494:pharmacology; D016106:Methicillin Resistance; D008875:Middle Aged; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000401:mortality*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification*
D000900:Anti-Bacterial Agents; D008712:Methicillin