LAUSR

We rarely biopsy bones in osteomyelitis and often have to treat empirically. Staphylococcus aureus has been considered the most common cause of childhood osteomyelitis and septic arthritis. However, direct injection of joint fluid into blood culture bottles, the improved BACTEC blood culture system, and molecular methods such as polymerase chain reaction have increased rates of detection of pathogens. A retrospective study of 369 children, aged 15 days to 15 years, with osteoarticular infections (OAI) admitted to a single centre in Geneva compared results for periods before (1997–2006) and after (2007–2016) introduction of polymerase chain reaction for Kingella kingae and 16S ribosomal RNA. Over time the incidence of osteoarticular infections rose from 18.3 to 32.7 cases per 100 000 per year and the mean age fell from 72.2 to 31.0 months (both P < 0.01) as more older infants and toddlers presented. The detection rate of a likely pathogen rose from 61 to 78%. The biggest difference in organisms was with K. kingae, which was detected in only 1 of 129 children in the first period and 83 (34%) of 241 in the second, when only 50 cases (20.7%) were caused by S. aureus (all sensitive to methicillin). Almost all Kingella infections were in children aged 6–48 months. Empiric antibiotic use should be based on local epidemiological data.