gms | German Medical Science

Objectives: Streptococci account for about 10% of periprosthetic joint infection (PJI). Because of high susceptibility to penicillin, the outcome of streptococcal PJI was expected to be better than caused by other pathogens, however conflicting data exist. Rifampin plays the key role in the treatment of Staphylococcus aureus PJI, but their significance in streptococcal PJI is unclear.

Methods: We retrospectively evaluated the treatment and outcome of patients with streptococcal PJI in our institution from 2009 to 2015. Cases were identified by review of the hospital-based PJI register. Diagnosis of PJI was established when at least one of following criteria applied: macroscopic purulence, presence of sinus tract, positive cytology of joint aspirate (>2000 leukocytes/µl or >80% granulocytes), acute inflammation in periprosthetic tissue, positive culture. Treatment success was defined by absence of signs of infection (pain, swelling, erythema, warmth, wound discharge, early loosening of the prosthesis) at each follow up at 3, 6, 12 months and at last contact. Fisher's exact test was employed to find significant differences between categorical variables.

Results and Conclusion: 30 streptococcal PJIs were included (13 hips and 17 knees). The median patient age was 73 years (range, 53-92 years). The route of infection was considered haematogenous in 16 cases and perioperative in 14 cases. 20 patients were treated with a two-stage revision, 8 patients with débridement and retention of the prosthesis and 2 patients with one-stage revision. Most patients (82%) presented with acute symptoms and 88% showed an increased CRP-level (mean, 147mg/l). All patients were treated with penicillin derivatives, whereas rifampin was added in 52% of the cases as adjuvant agent. The mean follow up time was 34 months (range, 5-71 months). Treatment failure was observed in 13 cases (43%). Treatments failed in 9 of 20 (45%) with two-stage revision, 4 of 8 (50%) with débridement and retention and none of 2 with one-stage revision. In patients with multiple previous septic revisions, the failure rate was higher (5 of 6 cases, 83%) than in those with no or one previous septic revision (8 of 24 cases, 33%, p=0.06), but didn't reach significance level. The treatment success was similar in patients treated with (5 of 12, 42%) and without adequate rifampin-combinations (12 of 18, 67%) (p=0.26).Contrary to literature reports, a high failure rate of 43% in streptococcal PJI was observed despite treatment according to the established algorithm. The addition of rifampin to the treatment regime did not improve the treatment outcome. Investigations with other biofilm-active substances against streptococcal biofilms are needed.