Introduction and Aims

The practice of prescribing an extended course of oral antibiotics (EOA) after primary hip or knee arthroplasty (THA, TKA) has become increasingly common, based on observational data that in some high-risk patients this practice may reduce the risk of periprosthetic joint infection (PJI). One potential harm of this practice is that the excess antibiotic exposure will predispose patients to infection with more difficult-to-treat organisms. We sought to determine whether the use of EOA, specifically with a first-generation oral cephalosporin, would be associated with a change in the microbiology of subsequent PJI within one year.

Results

The prevalence of Gram-negative and polymicrobial PJI was higher in the group that received EOA. However, patients who received EOA with a first-generation cephalosporin were not significantly more likely to have a PJI with an organism resistant to those antibiotics.

Conclusion and Discussion

Patients who were prescribed EOA had significantly different microbiology of their subsequent PJI. While our data does not indicate whether this shift led to worse outcomes, it is a useful reminder that antibiotic exposure alters a patient’s microbiome, and therefore the organisms causing their infections.