Staphylococcus aureus colonization and surgical site infections among patients undergoing surgical fixation for acute fractures.

Objectives: To identify risk factors for methicillin-susceptible (MSSA) and methicillin-resistant S. aureus (MRSA) nasal carriage and surgical site infection (SSI) among patients undergoing fracture fixation procedures who were included in a quality improvement protocol involving screening patients for S. aureus nasal carriage and treating carriers with intranasal mupirocin and chlorhexidine bathing.

Design: Retrospective cohort study.

Setting: Level 1 trauma center.

Participants: 1,254 adults who underwent operative fixation of 1,298 extremity or pelvis fractures between 8/1/2014 - 7/31/2017.

Methods: We calculated rates of S. aureus nasal carriage and SSI. We used multivariable stepwise logistic regression and selected the final models based on Akaike information criterion.

Results: Of the 1,040 screened first procedures, 262 (25.19%) were performed on S. aureus nasal carriers: 211 (20.29%) on MSSA carriers and 51 (4.90%) on MRSA carriers. Long-term care facility residence (odds ratio [OR] 3.38; 95% confidence interval [CI] 1.17-9.76) was associated with MRSA nasal carriage. After adjusting for statistically and clinically significant variables, MRSA carriage was significantly associated with any SSI (OR 4.58; 95% CI 1.63-12.88), S. aureus SSI (OR 10.11; 95% CI 3.25-31.42), and MRSA SSI (OR 27.25; 95% CI 5.33-139.24), whereas MSSA carriage was not. Among S. aureus carriers, any chlorhexidine use was documented for 232 (88.55%), and any intranasal mupirocin was documented for 85 (40.28%) MSSA carriers and 33 (64.71%) MRSA carriers.

Conclusions: MRSA carriage was associated with a significant risk of SSI after operative fracture fixation. Many carriers did not undergo decolonization, suggesting that a simplified decolonization protocol is needed.