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BMC Infect Dis. 2018 Jun 11;18(1):270. doi: 10.1186/s12879-018-3182-x.

Screening swabs surpass traditional risk factors as predictors of MRSA bacteremia.

Author information

1
Division of Infectious Diseases, Department of Medicine, McGill University Health Centre, 1001 Boulevard Décarie, room E05. 1917, Montreal, Quebec, H4A 3J1, Canada. guillaume.butler-laporte@mail.mcgill.ca.
2
Division of Infectious Diseases, Department of Medicine, McGill University Health Centre, 1001 Boulevard Décarie, room E05. 1917, Montreal, Quebec, H4A 3J1, Canada.
3
Division of General Internal Medicine, Department of Medicine, McGill University Health Centre, Montreal, Quebec, Canada.
4
Clinical Practice Assessment Unit, McGill University Health Centre, Montreal, Quebec, Canada.

Abstract

BACKGROUND:

Consideration to add empiric MRSA therapy with vancomycin is a common clinical dilemma. However, vancomycin overuse has important adverse events. MRSA colonization screening is commonly performed for infection control. We hypothesized that in cases of S. aureus bacteremia, a score based on patient level factors and MRSA colonization could predict the risk of MRSA infection and inform the need for empiric coverage.

METHODS:

Using modern machine learning statistical methods (LASSO regression and random forests), we designed a predictive score for MRSA infection based on patient level characteristics, and MRSA colonization as measured by screening done 30 days before infection (30-Day criteria), or at any time before infection (Ever-Positive criteria). Patient factors (age, sex, number of previous admissions, and other medical comorbidities) were obtained through our electronic records.

RESULTS:

With random forests, MRSA colonization largely surpassed all other factors in terms of accuracy and discriminatory power. Using LASSO regression, MRSA colonization was the only factor with MRSA infection predictive power with odds ratio of 10.3 (min: 5.99, max: 16.1) and 8.14 (min: 6.01, max: 14.8) for the 30-Day and Ever-Positive criteria, respectively. Further, patient comorbidities were not adequate predictors of MRSA colonization.

CONCLUSIONS:

In an era of community acquired MRSA, colonization status appears to be the only independent and reliable predictor of MRSA infection in cases of S. aureus bacteremia. A clinical approach based on a patient's known MRSA colonization status and on local susceptibility patterns may be appropriate.

KEYWORDS:

Bacteremia; Colonization; MRSA; Statistics; Vancomycin

PMID:
29890954
PMCID:
PMC5996459
DOI:
10.1186/s12879-018-3182-x
[Indexed for MEDLINE]
Free PMC Article

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