1365. Antibiotic prophylaxis type is a predictor of surgical site infections in neurosurgical patients with a history of MRSA or VRE colonization

Authors: Arjun Adapa; Joseph Linzey, BS; Aditya Pandey, MD (Ann Arbor, MI)

Introduction
Surgical site infections (SSIs) in neurosurgery are a significant cause of postoperative morbidity. The choice of antibiotic prophylaxis and the relationships between SSIs and patient preoperative characteristics are not fully understood for patients with methicillin-resistant staphylococcus aureus (MRSA) or vancomycin-resistant enterococcus (VRE) colonization. Thus, our aim was to understand the relationship between antibiotic prophylaxis type and the occurrence of SSI in neurosurgical patients with a documented history of MRSA or VRE colonization.

Methods
Data on all neurosurgical procedures between 2013 and 2018 was obtained from the University of Michigan Clinical Data Office. A retrospective analysis was conducted on a total of 9,739 unique surgical procedures. Among the data, important variables included MRSA or VRE status prior to surgery, demographic variables, antibiotics administered peri-operatively, SSI during admission, and SSI within 30 days after discharge. Ineffective prophylaxis was defined as those antibiotics that do not cover against MRSA or VRE. Standard statistical analyses were conducted.

Results
Of the patients screened for MRSA or VRE at any time prior to surgery, there were 744 unique surgical procedures (7.6% of all procedures in the data). Within the positive patients, there were 107 unique procedures, and within the negative patients, there were 637 unique procedures. In the 107 procedures in patients with a history of MRSA+ or VRE+, ineffective prophylaxis was given in 68.2% of procedures. Of these 107 procedures, those with ineffective antibiotic prophylaxis experienced a 13.4% rate of surgical site infections within 30 days of discharge, compared to 0% in those with effective antibiotic prophylaxis (p<0.005). Antibiotic prophylaxis type in patients with a known negative history of MRSA or VRE did not significantly affect rates of SSIs.

Conclusion
Ineffective antibiotic prophylaxis in neurosurgical patients with a history of MRSA or VRE led to significantly more SSIs.