Adverse Clinical Outcomes and Resource Utilization Associated with Methicillin-Resistant and Methicillin-SensitiveStaphylococcus aureusInfections after Elective Surgery

Abstract

Background: Current studies of post-operative Staphylococcus aureus disease focus primarily on surgical site infections and are often limited to infections caused by methicillin-resistant Staphylococcus aureus (MRSA). The objective of this retrospective cohort analysis was to describe the occurrence of and outcomes associated with post-operative MRSA and methicillin-sensitive S. aureus (MSSA) infections in patients undergoing elective surgical procedures. Methods: Data were extracted from Health Facts for inpatients aged 18 years or older with pre-defined International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) procedure codes, meeting additional criteria indicating that the procedure was elective. Post-operative S. aureus infection was identified by one or more qualifying culture positive for MRSA or MSSA. Multivariable regression models compared patients with MRSA, MSSA, and no S. aureus infection. Results: Among 34,866 qualifying patients, the incidence of S. aureus infections was 0.9% during the index admission and 1.7% within 90 d after elective surgery, of which 36.6% and 38.4% were MRSA, respectively. The highest rates were observed among patients undergoing general surgery (2.2% during index admission, 3.2% within 90 d) and plastic surgery (1.8% during index admission, 3.1% within 90 d). Patients with MRSA and MSSA experienced poorer outcomes than uninfected patients, based on index admission length of stay (LOS; mean, 30.2, 22.7, and 5.7 d, respectively), hospital charges ($165,651, $134,313, and $52,077), and hospital mortality (odds ratios, 6.4 for MRSA, 4.8 for MSSA versus uninfected patients). Relative to MSSA infection, MRSA infection was associated with greater total hospital LOS and hospital charges but not with increased re-admission or mortality. Conclusions: The burden of post-operative S. aureus infection is shared among elective surgical procedures, however, rates and types of infections vary. Whereas MRSA infection results in substantially greater health care cost and LOS, mortality and re-admission rates are similar among patients with MRSA and MSSA. In elective surgery, infection control and surveillance for both MRSA and MSSA are warranted.