Off-label use of intravenous rifampicin during surgery: analysis of Australian surveillance data and retrospective audit at a tertiary hospital.

Objective: To investigate the use of rifampicin vials in Australian operating theaters (OT) to determine the method of administration and rationale for use.

Methods: Retrospective (2022 and 2023) OT usage data for rifampicin 600 mg vials were analyzed to compare trends in use between Australian hospitals and between jurisdictions. An audit of rifampicin vials used in OT during 2023 was conducted at a large tertiary hospital.

Results: Fifty-nine of 248 hospitals (24%) contributing data to the National Antimicrobial Utilisation Surveillance Program recorded OT use of rifampicin vials during 2022 and 2023. Excluding hospitals with no usage, the median use was 7 vials/annum/per hospital (IQR: 2-32). A wide variation in use was seen between Australian states and territories. An audit of OT use in 2023 at a large tertiary hospital found poor documentation of topical use; in most cases, documentation was in the operation note only, with no documentation on the medication charts, medical notes, or the anesthetic record. Of 33 rifampicin vials used in 2023, documented topical use was identified for 10 individual patients only, 4 of whom had a confirmed Staphylococcus aureus infection (1 methicillin-resistant and 3 methicillin-susceptible).

Conclusion: Off-label, topical use of rifampicin during surgery is not uncommon in some Australian hospitals despite limited evidence of safety or efficacy. Given the potential for resistance, surgical use of rifampicin should be restricted to a named-patient basis, under the guidance of an infectious disease specialist/clinical microbiologist. Documentation of all medication use is recommended for patient safety.