Clinical features and outcome of Streptococcus agalactiae bone and joint infections over a 6-year period in a French university hospital

Background Bone and joint infections (BJIs) due to Streptococcus agalactiae are rare but has been described to increase in the past few years. The objective of this study was to describe clinical features and outcomes of cases of S. BJIs. Methods We conducted a retrospective analysis of adult cases of S. agalactiae BJIs that occurred between January 2009 and June 2015 in a French university hospital. The treatment success was assessed until 24 months after the end of antibiotic treatment. Results Among the 26 patients included, 20 (77%) were male, mean age was 62 years ± 13 and mean Charlson comorbidity index score was 4.9 ± 3.2. Diabetes mellitus was the most common comorbidity (n = 14, 54%). Six had PJI (Prosthetic Joint Infections), five osteosynthesis-associated infections, 11 osteomyelitis and four native septic arthritis. Eleven patients had a delayed or late infection: six with a prosthetic joint infection and five with an internal fixation device infection. Sixteen patients (62%) had a polymicrobial BJI, most commonly with Gram-positive cocci (75%) notably Staphylococcus aureus (44%). Polymicrobial infections were more frequently found in foot infections (90% vs 44%, p = 0.0184). During the two-year follow-up, three patients died (3/25, 12%) and seven (7/25, 28%) had treatment failure. Conclusion Diabetes mellitus was the most common comorbidity. We observed an heterogenous management and a high rate of relapse.