Abstract
Aim
Antimicrobial suppression has shown to significantly improve treatment success of streptococcal periprosthetic joint infection (PJI) compared to 12-week standard antimicrobial therapy, however, only short-term follow-up was investigated. In this study we assessed the impact of suppression on the long-term outcome of streptococcal PJI.
Method
Consecutive patients with streptococcal PJI (defined by EBJIS criteria) treated 2009–2021 were prospectively included and allocated into standard and suppression (> 6 months) treatment group. Infection-free survival was assessed with Kaplan-Meier-method and compared between the groups with log rank test. Rates of infection-free, streptococcal infection-free and relapse-free status as well as tolerability of suppression were assessed.
Results
Sixty-three PJI episodes (36 knee, 26 hip and one shoulder prosthesis) of patients with a median age of 70 (35–87) years were included. Twenty-seven (43%) were females. Predominant pathogens were S. agalactiae (n=20), S. dysgalactiae (n=18) and S. mitis/oralis (n=13). The main surgical procedures used were two-stage exchange (n=35) and prosthesis retention (n=21). Standard 12-week treatment was administered in 33 patients and suppression in 30 patients, of whom 10 had ongoing suppression and 20 had discontinued antibiotics at time of follow-up. Used oral antibiotics for suppression were amoxicillin (n=29), doxycycline (n=5) and clindamycin (n=2); 6 patients changed antibiotic substance due to side effects. The median follow-up time was 3.9 (0.3–13.3) years. Infection-free survival after 7.5 years was 38% with standard treatment and 62% with suppression (p=0.038). Of all failures, 52% (14/27) were due to streptococci. Suppression was effective in preventing streptococcal infection for the duration of antimicrobial treatment, however, after discontinuation relapses or new infections due to streptococci occurred in 5/20 (25%) patients and infection with any Streptococcus spp. was observed in 9/19 (47%) failures with standard treatment, 5/6 (83%) failures after discontinuing suppression and none during suppression. All failures in patients with ongoing suppression were caused by gram-negative rods.
Conclusion
At long-term follow-up, the success rate was superior with suppression compared to standard treatment. Most failures after stopping suppression were caused by streptococci, whereas failures under suppression were caused by aerobic gram-negative rods.
