Paper of the week: Continuous Antibiotic Therapy Can Reduce Recurrence of Prosthetic Joint Infection in Patients Undergoing 2-Stage Exchange. Ascione T, Balato G, Mariconda M, Rotondo R, Baldini A, Pagliano P. J Arthroplasty. 2018 Dec 20. pii: S0883-5403(18)31218-X. doi: 10.1016/j.arth.2018.12.017
Summary and editorial by Sreeram Penna
The main aim of this observational cohort study is to compare infection recurrence in patients who had continuous antibiotic therapy versus antibiotic holiday period prior to reimplantation following two-stage revision for periprosthetic joint infection (PJI). Researchers also analyzed factors associated with poor outcome in patients undergoing two-stage revision procedure who had normalization of serum markers and improvement of symptoms prior to reimplantation. All patients in the study had two weeks of intravenous antibiotics followed by six weeks targeted oral antibiotics.
A total of 196 patients were included in the study. 110 patients had continuous antibiotic therapy prior to reimplantation, and 82 patients had an antibiotic holiday. Overall 169 (86%) patients had a favorable outcome, and 14% had PJI recurrence. In the group that had continuous antibiotics, the cure rate was 91% (104/110) versus 79% (65/82) in patients who had antibiotic holiday prior to reimplantation, and this result was statistically significant (p=0.029). Further analysis revealed that the cure rate was significantly (p=0.02) better in immunocompromised patients receiving continuous antibiotics (41/46, 89%) versus patients who had an antibiotic holiday (20/31, 65%). Immunocompromised patients included those with diabetes, liver cirrhosis, autoimmune disease, and those who were on immunosuppressive medication.
The study also found that serum markers, body mass index, and positive microbiology at reimplantation did not affect the overall outcome. Immunocompromised patients and culture-negative cases were associated with poor outcome following a two-stage procedure. Of the culture positive cases, patients with Gram-positive cultures had a better outcome compared to Gram-negative cases. In another study done by Herman et al., researchers found that CRP and other classic markers like synovial white cell count and PMN % performed poorly in identifying residual infection prior to reimplantation. In addition as researchers noted in this study that antibiotic holiday was shown to have poor outcomes especially in immunocompromised patients, as conditions for bacterial regrowth are still present. This paper puts forth an important argument to continue antibiotic treatment until reimplantation. However further research is needed to identify the optimal time and predictive factors to calculate the success of reimplantation.
 Herman A, Albers A, Garbuz DS, Duncan CP, Masri BA. Classic Markers for Infection Perform Poorly in Predicting Residual Infection Prior to Reimplantation. Orthopedics 2019;42:34–40. doi:10.3928/01477447-20190103-03.