Osteomyelitis In Infants Younger Than One Month: A Case Report

Abstract

Background: Neonatal osteomyelitis is a rare but potentially serious bone infection; its nonspecific clinical presentation can hinder early diagnosis. Key signs include irritability, reduced mobility of the affected limb, and local inflammatory manifestations, which may occur in the absence of fever. Timely diagnosis and treatment are essential to prevent permanent orthopedic sequelae. Aim: To report a case of acute osteomyelitis of the left distal femur in a 29-day-old newborn, highlighting clinical, laboratory, and radiological findings, the therapeutic approach, and the patient's progress after five months of follow-up.

Method: A descriptive case report based on a retrospective analysis of clinical data, diagnostic tests, microbiological results, treatment, and the clinical course of a newborn treated at the Hospital Universitário São Francisco na Providência de Deus. The study was approved by the Research Ethics Committee of the Universidade São Francisco (Opinion No. 8,809,224, dated October 17, 2026; CAAE 01469026.4.0000.5514).

Results: A 29-day-old male newborn presented with irritability, edema, hyperemia, and reduced mobility of the left lower limb, with no documented fever. Diagnostic tests revealed leukocytosis (21,900/mm³), an erythrocyte sedimentation rate (ESR) of 121 mm/h, a C-reactive protein (CRP) level of 190, and a lytic lesion in the left distal femur involving the epiphysis, physis, and metaphysis. The patient underwent emergency surgical debridement, with drainage of purulent discharge; cultures identified *Streptococcus agalactiae*. He received systemic antibiotic therapy and remained hospitalized for 14 days. Five months later, there was good wound healing, preserved joint mobility, and radiographic evidence of reossification, with no further interventions required.

Conclusion: Neonatal osteomyelitis requires a high index of clinical suspicion, especially in the presence of reduced mobility and local signs of inflammation, even in the absence of fever. This case demonstrates that timely diagnosis and treatment can lead to a favorable clinical and functional outcome. However, potential involvement of the growth plate underscores the need for long-term orthopedic follow-up to monitor for possible late-onset sequelae.