Osteoarticular infections in infants under 3 months of age

Background Acute osteoarticular infections (OAI) in infants under 3 months of age (<= 3M) are rare and remain a diagnostic challenge. Orthopedic complications and functional sequelae have been less well described in this age group. Our aims were to evaluate trends in aetiology, management, and outcomes of OAI <= 3M, and to compare these younger children who have OAI with older children. Methods A longitudinal observational study was conducted of OAI cases admitted to tertiary care pediatric hospital from 2008 to 2018. OAI <= 3M was compared with children above 3 months. Clinical, microbiological, imaging, and outcome data were analyzed. Results We identified 24 (9.1%) of the 263 OAI in children under 3 months. Analyzing OAI <= 3M there was a twofold increase since 2014; 54% were males with a median age of 28 days (IQR: 13.5-60.0), 10 (41.7%) were premature and nine (37.5%) had healthcare-associated infections. Microbiological causes were identified in 87.5%, mostly Staphylococcus aureus (57.1%) and Group B Streptococcus (23.8%), and 25% were multidrug-resistant (5 methicillin-resistant S. aureus and 1 Enterobacter cloacae). Bacteremia (100% vs 36.8%, P = 0.037), multidrug resistant bacteria (75% vs 16, P = 0.04), and healthcare-associated infections (100% vs 26.3%, P = 0.014) were associated with sequelae. Comparing OAI <= 3M with older children, OAI <= 3M were treated with longer antibiotic courses, had more complications and sequelae (17.4% vs 3.2%, P = 0.002). Conclusions S. aureus is still the most common cause of OAI <= 3M, and 25% of causative bacteria were multidrug-resistant bacteria. Complications and sequelae were more frequent in OAI <= 3M when compared with older children.