1376. An Analysis of Weight Based Dosing for Sulfamethoxazole-Trimethoprim in Skin and Soft Tissue Infections

Abstract

Abstract Background Guideline recommendations for sulfamethoxazole-trimethoprim (TMP/SMX) in skin and soft tissue infections (SSTIs) are 1 to 2 double strength (DS) tablets by mouth twice daily. Studies suggest that weight-based dosing of TMP/SMX for SSTIs has a clinical impact on treatment failures. One study suggested TMP/SMX dosed at < 5mg/kg/day, based on the trimethoprim component, was inadequate for the treatment of SSTIs. There are currently no studies to date that assess the incidence of treatment failures with TMP/SMX dosed at ≥ 5mg/kg/day compared to < 5mg/kg/day. Methods A single center, retrospective chart review was conducted on adult patients diagnosed with a SSTI based on ICD-9/10 codes from January 2009 through August 2021 at University Health Truman Medical Center. Patients included were divided into two groups based on the dosing strategy of TMP/SMX (< 5mg/kg/day or ≥ 5mg/kg/day). The primary and secondary outcome was incidence of treatment failures and incidence of adverse events, respectively. Exploratory variables that may influence treatment failures were also collected. Results A total of 351 patients were included in the analysis with 190 in the < 5mg/kg/day group and 161 in the ≥ 5mg/kg/day group. Patients dosed at ≥ 5mg/kg/day had significantly less treatment failures compared to those dosed at < 5mg/kg/day (17.4% vs 7.5%, p=0.006). After a multivariate analysis, patients dosed with TMP/SMX at ≥ 5mg/kg/day were 58% less likely to have a treatment failure (OR 0.42, 95% CI 0.17 to 0.96, p=0.044). Incidence of adverse events were similar in both groups (p=0.105). Conclusion TMP/SMX dosed at ≥ 5mg/kg/day had significantly fewer treatment failures for SSTIs compared to TMP/SMX dosed at < 5mg/kg/day and was not associated with increased adverse events. These findings suggest that the current recommendations for dosing of TMP/SMX in SSTIs may need to be addressed. Disclosures All Authors: No reported disclosures.