The Impact of Oral Antibiotics on Culture Data for Post Operative Wound Infection Following Craniotomy

Introduction: Surgical site infections (SSI) following craniotomy for tumor are a significant cause of morbidity. Surgeons often prescribe oral antibiotics in the post-operative setting for infected-appearing wounds in order to prevent reoperation for infection, however, the effects of this practice on intraoperative culture data are not well-characterized.

Methods: Patients requiring reoperation for infection following craniotomy for tumor were retrospectively reviewed at the University of Pennsylvania from 2014 to 2018 and grouped based on prescription of an oral antibiotic for superficial SSI. Demographic and clinical variables collected are detailed in Table 1. T-tests were used to compare continuous variables and chi square analysis was used for categorical variables.

Results: 32 patients required reoperation for infection following craniotomy for tumor. 13 patients received a course of oral antibiotics prior to reoperation for infection. 19 patients proceeded to reoperation without a trial of oral antibiotics. There were no differences in clinical and demographic data. Prescription of an oral antibiotic did not affect the odds of obtaining a positive culture result (OR 2.25, CI 0.21-24.4, p 0.51). Intraoperative vancomycin did not significantly affect the odds of obtaining a gram-negative organism (OR 2.4, 95% CI 0.31-18.6, p 0.4). Prescription of an oral antibiotic resulted in a later date for reoperation – post operative day 51.9 versus 30.8 (p 0.005). The three most commonly isolated organisms were MSSA, p.acnes, and CONS (Figure 1). The most commonly prescribed antibiotics were Keflex (30.8%), Levaquin (30.8%), and Bactrim (23.1%). Sensitivity data was available for 11 patients within the oral antibiotic group. 7 of 11 (63.6%) bacterial isolates were sensitive to the oral antibiotic prescribed.

Conclusion : Prescription of oral antibiotics for concerns of superficial SSI did not affect the odds of obtaining culture data needed for targeted antibiotic therapy following reoperation, but may prolong time to definitive treatment with washout.