Oral Therapy, Microbiological Findings, and Comorbidity Influence the Outcome of Prosthetic Joint Infections Undergoing 2-Stage Exchange

Background The aim of the present study was to investigate potential predictive factors of an unfavorable outcome in patients with prosthetic joint infection (PJI) undergoing 2-stage exchange. Methods Patients with PJI undergoing 2-stage exchange and observed over a 5-year period (2009-2013) were included. Cure was defined by the disappearance of infection after a 96-week follow-up period. Statistical analysis was performed using Mann-Whitney U test, Fisher's exact test, and multivariate analysis. Results One-hundred and twenty-two patients with PJI were included [(median age 69 years), range 36-80], 48% males, 47 hip PJI and 75 knee PJI). Known comorbidities related to an increased risk of infection were reported in 43 patients (35%). Microbiological definition was obtained in 101 (83%), and Staphylococcus aureus was isolated in 44 (36%). Coagulase-negative staphylococci were isolated in 41 (34%). A favorable outcome was obtained in 102/122 patients (84%). After univariate analysis, bacterial growth from operative specimens (P=.007), growth of Gram-positive (p< .001), use of oral therapy (P=.01), and absence of known comorbidities (P=.02) were associated with favorable outcome. Administration of rifampin (P=.99) and results of blood analysis were not predictive of outcome. After multivariate analysis was applied, infection sustained by Gram-positive bacteria, administration of oral antibiotics, and absence of known comorbidities frequently resulted in favorable outcome. Conclusions A favorable outcome in patients with PJI undergoing 2-stage procedure was associated with an infection sustained by Gram-positive bacteria, absence of known comorbidities, and administration of oral therapy. Therefore, failure rate can be reduced with appropriate treatment choices.