Background: Patients who present to VA hospitals are screened for methicillin resistant Staphylococcus aureus (MRSA) colonization. Those who test positive are isolated during their hospital stay. However, it is unknown which of these patients are most likely to subsequently develop active MRSA infections.
Methods: Our retrospective-case-control study characterized risk factors for active MRSA infection among patients colonized with MRSA during acute care hospital admission. Potential demographic and clinical risk factors were identified using electronic queries and manual chart abstraction; data were compared by standard statistical tests and variables with P values < 0.05 in bivariable analysis were entered into a multivariable logistic regression model.
Results: There were 71 cases and 213 controls. Risk factors associated with MRSA infection included diabetes mellitus with or without end organ damage (26% vs. 14%, p=0.02), hemiplegia (9% vs. 2%, p=0.01), chronic kidney disease (33% vs. 20%, p=0.03), post-colonization inpatient admission within 90 days (44% vs 29%, p=0.03), surgery (41% vs. 9%, p<0.01), and dialysis (10% vs. 3%, p=0.02). On multivariable analysis, surgery during follow-up, dialysis during follow-up, and hemiplegia remained significant.
Conclusion: Among patients with MRSA colonization, surgery or dialysis during follow-up, and history of hemiplegia, were associated with subsequent MRSA infection. Knowledge of these risk factors might enable future targeted interventions to prevent MRSA infections among colonized patients.