**2. Epidemiology**

In Western countries the incidence of osteomyelitis and septic arthritis is 5-12 per 100.000 infants [3]. The overall incidence rate for bone and joint infections is 0.12 per 1000 live births and 0.67 per 1000 neonatal intensive care (NICU) admissions [4], with a mortality rate of 7.3% [5]. Some recent studies have reported an estimated incidence of 1-7 per 1000 hospital admissions for neonatal osteomyelitis [6,7]. In a review of more than 300 cases of neonatal osteomyelitis male infants are seen to predominate over females (1.6:1) and preterm infants to be at higher risk than term infants [8-10]. Risk factors for osteomyelitis and septic arthritis in preterm infants are mostly iatrogenic, including invasive procedures, intravenous or intra-arterial catheters, parenteral nutrition, ventilatory support, and bacteremia with nosocomial pathogens [11,12]. Two subgroups of neonates are affected: premature neonates with prolonged hospitalization and otherwise healthy newborns presenting within 2 to 4 weeks of discharge [13].
