Acute haematogenous osteomyelitis in infancy and childhood

Acute hematogenous osteomyelitis is an infection that usually affects the growing skeleton, involving primarily the most vascularized regions of the bone. It is considered an acute process if the symptoms have lasted less than 2 weeks (2,3). Acute osteomyelitis has an incidence of 8–10 per 100 000 in developed countries and an even higher incidence, up to 80 per 100 000, in developing countries (1,4,5). The incidence of septic arthritis is about half that of osteomyelitis. In the United States, there has been a 2.8-fold increase in the incidence of osteomyelitis in the past 2 decades (6). By contrast, over this same period, the incidence of septic arthritis has remained unchanged (7).

The most common organism that infects the bones is Staphylococcus aureus, followed by the respiratory pathogens Kingella kingae, Streptococcus pyogenes, and Streptococcus pneumoniae (1,6,8). Both methicillin-sensitive and methicillin-resistant isolates of S aureus are associated with osteomyelitis. Methicillin-resistant S aureus (MRSA) accounts for 30%–40% of osteoarticular infections in the United States and a lower percentage of cases in northern Europe and the Middle East (2). The course of community-acquired S aureus osteomyelitis appears to be more severe in recent years, primarily in cases caused by MRSA and potentially related to the presence of the Panton-Valentine leucocidin, or PVL, gene. This gene encodes for a toxin that produces tissue necrosis and destruction of neutrophils (9), and is associated with a higher rate of septic shock and greater need for surgical interventions and prolonged hospitalization (10). Children with PVL-positive staphylococcal infections are more likely to have multifocal osteomyelitis, large subperiosteal abscesses, multiple bony abscesses, deep venous thrombosis, and associated myositis and pyomyositis (11).