Risk Factors for Methicillin Resistant Staphylococcus aureus Skin and Soft Tissue Infections in Patients Found to be Colonized When Admitted to an Acute Care Hospital
MRSA infections are common in patients admitted to US hospitals. Little is known about the impact of asymptomatic MRSA colonization post-discharge in the setting of active MRSA surveillance. This study aimed to determine the risk factors for MRSA SSTI among patient with MRSA nasal colonization detected during an acute care hospital admission
Retrospective, case-control study of patients admitted to the Audie L. Murphy VA Hospital in San Antonio, Texas. Patients included were ≥18 years old and colonized with MRSA during an acute care hospital admission. Patients on hospice, bone marrow transplants and with MRSA infections upon admission were excluded. We matched 28 patients who developed a MRSA SSTI to 84 controls by length of follow-up (±10 days, up to 18 months), and collected demographics, known clinical risk factors for MRSA infection and comorbidities. Chi-square and t test were used for bivariate analysis. A multivariable logistic regression model was used to identify risk factors for MRSA SSTIs post-discharge. P-values <0.05 were considered significant.
Mean age (60.8 years -cases- vs.66.6 years- controls-) and mean Charlson comorbidity score (6.9 vs.6.6) were similar among cases and controls. Factors associated with MRSA SSTIs post-discharge were prior hospital admission within 12 months (19 cases,67.9% vs. 33 controls,39.3%), MRSA infection prior to hospital admission (8 cases,28.6% vs. 7 controls,8.3%),history of myocardial infarction (8 cases ,28.6%vs. 4 controls ,4.8%), and peripheral vascular disease (8 cases,28.6% vs. 7 controls ,8.3%). Prior antibiotic use was inversely associated with MRSA SSTI (11 cases,39.3% vs. 62 controls ,73.8%). In multivariable analysis, prior hospital admission within 12 months (p=.006) and a history of myocardial infarction (p = .003) were independently predictive of a MRSA SSTI. Antibiotics three months prior to infection/end of follow up were protective (p =0.001).
Prior hospital admission within 12 months and a history of myocardial infarction are independent risk factors for MRSA SSTIs. Antibiotic use was protective for MRSA infection. Future studies should evaluate these findings as they may be used to design novel preventive interventions.
J. Cadena, Cubist Pharmaceuticals: Grant Investigator, Research grant