Zastrow RK, Huang HH, Galatz LM, et al. - As there are numerous antibiotic prophylaxis options for total hip and knee arthroplasty (THA, TKA), researchers sought to describe antibiotic utilization patterns and their associations with infection risk. They hypothesize that infection risk may differ by the regimen used. In this retrospective cohort study, data from 436,724 THA and 862,918 TKA (Premier Healthcare Database; 2006-2016) were assessed for main exposures comprising antibiotic type and duration: day of surgery only (day 0) or through postoperative day 1 (day 1). Analysis revealed surgical site infection (SSI) prevalence of 0.21% (n = 914) for THA and 0.22% (n = 1,914) for TKA. Cefazolin (74.1%), vancomycin (8.4%), ‘other’ antibiotic combinations (7.1%), vancomycin + cefazolin (5.1%), and clindamycin (3.3%) were the most commonly used antibiotics among THA procedures. Here, prophylaxis was provided on day 0 only in 51.8% while prophylaxis was provided through day 1 in 48.2% cases. They observed similar patterns for TKA. Raised SSI risk was seen among THA/TKA patients in correlation with antibiotic prophylaxis regimens other than cefazolin. Findings thereby emphasize a modifiable intervention to reduce infection risk.