Neonatal osteomyelitis: a case series and literature review

Neonates have a number of risk factors that make them susceptible to bone and joint infections. Pathogens can access the bone through the bloodstream (hematogenous spread), direct inoculation (traumatic or procedural), or by contiguous spreading from nearby infected soft tissues or synovial fluid. Studies focused on neonatal osteomyelitis are very rare and most of them only involved a small number of cases. This study aimed to describe the cases of neonatal osteomyelitis in one of the largest neonatal intensive care units in China across a 6-year time period and to compare the results with those reported in the latest literature.

This study retrospectively reviewed the data of clinical characteristics, etiologies and outcomes in neonates with osteomyelitis from 2016 to 2021 in Children's Hospital of Fudan University and compared our results with six large case series (>10 cases) of neonatal osteomyelitis reported in the past 30 years.

Fifteen neonates were identified, accounting for 0.05% of the total neonatal admissions. The median [interquartile range (IQR)] gestational age was 37.9 (IQR, 36.6-39.9) weeks, and one-third were preterm infants. The median (IQR) birth weight (BW) was 3,000 (IQR, 2,400-4,000) grams and 26.7% were of BW <2,500 g. The median (IQR) age at onset was 7 (IQR, 6-16) days after birth, and the median (IQR) time from symptom onset to confirmed diagnosis was 5 (IQR, 1-10) days. The most common presenting signs were fever, local swelling and reduced mobility of the affected segment. Femur was the most frequently affected site (66.7%) and 73.3% neonates had ≥2 bones involved. Staphylococcus aureus was the most common organism identified (40.0%), but there were 40.0% patients with negative cultures. The median (IQR) duration of intravenous antibiotic therapy and length of hospital stay was 29 (IQR, 25-42) and 30 (IQR, 29-42) days, respectively. The patients were followed up for a median (IQR) time of 9 (IQR, 2-19) months. All patients survived, but 40.0% presented with joint deformity during follow-up. The data from the latest literature showed a wide variability, in which about 1/4 had negative cultures, over 1/2 required surgical intervention, and 13.4% had sequelae during follow-up.

Neonates with osteomyelitis required a long duration of antibiotics and had a high rate of sequelae. The treatment of neonatal osteomyelitis remains challenging, especially for those with negative culture. Further research is needed to investigate the proper duration of antibiotics administration and the indicators for switching antibiotics from intravenous to oral therapy for this population.