Invasive group B streptococcal disease in an orthopaedic unit.

Invasive group B streptococcus (GBS) is an increasing cause of infection in orthopaedic patients. Risk factors include increasing age, diabetes mellitus and immune deficiency. It may cause native and periprosthetic joint sepsis, cellulitis, fasciitis, soft tissue abscesses and osteomyelitis. We describe the epidemiology and outcome from GBS infection in a large cohort of general orthopaedic patients. All those presenting to our institution with deep tissue or aspirate samples containing group B streptococcus over three years were identified and their case records examined retrospectively. There were 17 cases, giving an annual incidence of 0.69 per 100000 adult population. They comprised 0.12% of all emergency admissions. Eight were related to joint prostheses, giving an incidence of 0.15% following joint replacement. Other infections related to underlying metalwork, osteomyelitis or chronic soft tissue infection. All the isolates were susceptible to benzylpenicillin, but six demonstrated intermediate resistance to macrolides. Sixteen patients required surgical debridement, and two ultimately required amputations. This study should raise awareness of GBS as a potential infectious agent in soft tissue and joint infections in patients with specific risk factors.