To Rifamp or not?

Contributed by Dr Bhanuprasad

Prosthetic joint infection (PJI) is a rare but devastating complication after joint replacement especially after revision surgery leading to prolonged hospital stay, cost and morbidity. Gram positive bacteria especially staphylococcus infection (Coagulase Negative Staphylococcus species {CONS}> Staphylococcus aureus) secretes glycocalyx which fuses with bacterial colonies forms biofilm over the prosthetic material which harbours various dormant stages of bacteria limiting the antibiotic reach leading to persistent infection of bone and joint. Rifampicin is being used as a combination therapy with other standard staphylococcus antibiotics especially with DAIR (limited Debridement, Antibiotics and Implant retention) considering its ability to penetrate the biofilm and eradicate dormant bacteria but there was only limited data with no large randomised control trails (RCT) done to show beneficial effect rifampicin combination therapy over monotherapy.

A recently published multicentre open label RCT by Karlsen and colleagues studied 99 patients with culture proven staphylococcal early PJI after hip and knee arthroplasties within 30 days of surgery or within 3 weeks of bacteremia who underwent DAIR, comparing rifampicin combination therapy vs anti staphylococcal antibiotic (cloxacillin or vancomycin) monotherapy for total 6 weeks.

Over all 33 patients into Rifampicin group and 32 patients into the monotherapy were randomised but there many dropouts in study (10 & 7 patients respectively) which are not included in the intention to treat analysis. Among the two groups baseline characterstics / comorbidities were well matched with a median time from index surgery to revision of 18 days, methicillin sensitive staph aureus is being the predominant pathogen in the early PJI. There is no difference in the cure (lack of clinical, biochemistry or radiological signs of infection at 2 years follow-up) between the rifampicin combination group (17 of 23 (74%)) and the monotherapy group (18 of 25 (72%), relative risk 1.03, 95% confidence interval 0.73 to 1.45, p = 0.88). Despite the limitations of small sample size, addition of rifampicin did not enhance cure in patients with established culture proven difficult to treat staphylococcus early prosthetic joint infection.

References

  1. J Orthop Surg Res. 2020; 15: 365