Abstract
Aim
The aim of our study was to identify pathogens involved in septic knee arthritis after ACLR and to describe clinical features, treatment and outcome of infected patients.
Methods
We conducted a retrospective observational study including all patients with ACLR infection in 3 orthopedic centers sharing the same infectious disease specialists.
Results
During a seven-year period (2011–2017) we identified 74 infected patients among 9858 patients who had ACLR (incidence rate = 0.0075). Fourteen patients had polymicrobial infection. We identified 89 pathogens. Twenty four patients (34.4 %) were infected with S. aureus (27% of all isolates)(only one oxacillin-resistant strain). C. acnes was the second most frequent pathogen, identified in 14 patients (18.9%) (15.7% of all isolates). S. lugdunensis was identified in 9 patients (12.2%) (10.1% of all isolates). S. caprae was as frequent as S. epidermidis identified in 8 patients each (10.8%) (9 % of all isolates for each). No strain of S. lugdunensis and S. caprae was resistant to oxacillin, levofloxacin or rifampicin. Ten patients infected by C. acnes, 8 infected by S. lugdunensis, and 7 infected by S. caprae had an early acute infection. In all cases but one an arthroscopic lavage was performed, in 14 cases two lavages were required and in 4, 3 lavages. All patients infected by a strain susceptible to levofloxacin and rifampicin, including those with C. acnes, S. caprae and S. lugdunensis infection, were treated with an oral combination of levofloxacin and rifampicin, after a couple of days of IV empirical treatment with vancomycin and a broad spectrum beta-lactam. The median duration of treatment was 6 weeks. Seventy one patients were considered cured.
Conclusions
To our knowledge this is the largest reported series of infection after ACLR. S. aureus is the main pathogen (27% of all strains). C. acnes, S. lugdunensis and S. caprae accounted for almost 35% of pathogens and 38% of infections. A conservative strategy consisting in arthroscopic lavage(s) and a 6-week treatment with levofloxacin and rifampicin was effective.
