In the Era of Precision Medicine, Is It Time for Disease-Specific Antibiograms?

Abstract Corresponding Author Katherine Wierzbowski, MD; katherine-wierzbowski@uiowa.edu Funding None. Conflict(s) of Interest None of the authors have any conflict of interest to disclose. Background National guidelines on the management of children with acute osteoarticular infections (AOI) recommend consideration of empiric therapy targeting methicillin-resistant S. aureus (MRSA) based on a community prevalence of 10-20% or greater. Due to potential toxicity or resistance, targeted empiric use of anti-MRSA agents such as vancomycin or clindamycin is an important consideration. Institutional antibiograms are used to guide appropriate antibiotic prescribing, however, do not take into consideration patient or disease specific factors. While having an institutional MRSA incidence of 27% in children, review of culture-confirmed AOI cases determined a disease-specific incidence of MRSA of 13%. We aimed to reduce empiric vancomycin use for children with AOI by application of a disease-specific antibiogram. Methods Charts of patients aged 1 to 18 years old admitted to our institution from January 2018 to August 2023 with ICD 10 codes of AOI were retrospectively reviewed. Rate of empiric initiation of vancomycin prior to CPG implementation was compared to the post-implementation period using two-sample t-test. Secondary objectives included use of empiric anti-MRSA coverage, percentage of positive cultures, incidence of MRSA, length of stay (LOS), and hospital 30-day readmission rate (RR). Results Of 292 charts reviewed, 90 were included in the final analysis with 52 pre-and 38 post-implementation. Empiric vancomycin selection pre- and post-implementation was 46% and 26%, respectively (p=.05). Empiric anti-MRSA coverage decreased from 28 cases (54%) to 11 post CPG implementation (29%) (p=.017) while patients discharged on anti-MRSA therapy was similar pre/post (15 29% pre- and 6 16% post-implementation p=.14). All 90 patients had at least one sample obtained for culture and 56 patients had at least one positive culture (62%). Of those, 9 had MRSA positive cultures; MRSA incidence pre- an post-implementation was unchanged at 13% and 11% respectively (p=.82). The RR (7.7 vs 7.9%) and LOS (5.5 vs 5.6 days) were unchanged. Conclusion Application of a disease-specific antibiogram allowed reduction of empiric anti-MRSA therapy, specifically vancomycin, for AOI without changing LOS and RR. These results suggest that while institution-wide antibiograms can be beneficial, a disease and population specific antibiogram can lead to more appropriately tailored therapy.