Invasive Bacillus cereus infection in hospitalized preterm infants: clinical characteristics, outcomes, and neurological complications from a single-center retrospective case series

Bacillus cereus is an uncommon but potentially serious cause of healthcare-associated infection in preterm infants. Potential sources include contaminated environmental surfaces, medical equipment, and nutritional products. This study investigated the clinical characteristics, treatment, and outcomes of B. cereus sepsis in hospitalized preterm infants, with particular attention to central nervous system complications. Clinical data from hospitalized preterm infants diagnosed with B. cereus sepsis and admitted to the Neonatal Intensive Care Unit of Quanzhou Maternal and Child Health Hospital between May 2023 and February 2025 were retrospectively analyzed. A detailed description of one case of brain abscess was provided, and a literature search was conducted for published cases of neonatal B. cereus brain abscess. Nineteen hospitalized preterm infants with a median age at onset of 16 days (range, 7–223 days) were included. The initial clinical manifestations included poor responsiveness (100%), fever (14 patients, 73.9%), and apnea (12 patients, 63.2%). Among the 16 infants who did not receive invasive mechanical ventilation before onset, 10 (62.5%; 95% CI, 35.4%–84.8%) required escalation to a higher level of respiratory support following sepsis onset. All strains were penicillin- and ampicillin-resistant, but susceptible to meropenem, vancomycin, and linezolid. Two cases (10.5%) were complicated by purulent meningitis; one progressed to a brain abscess. The overall mortality rate was 5.3% (1/19; 95% CI, 0.1%–26.0%). The child with a brain abscess survived after surgical drainage and long-term antimicrobial therapy but exhibited mild neuromotor developmental delay at 20 months of age. A literature review, together with this case, identified 15 cases of neonatal B. cereus brain abscess, among whom five deaths were reported (33.3%); some survivors had neurological sequelae. The clinical presentation of B. cereus sepsis in hospitalized preterm infants is non-specific, and an escalation of respiratory support was commonly observed during sepsis onset. Brain abscess represents a severe neurological complication, and some survivors may experience neurodevelopmental sequelae. In addition to early identification and appropriate antimicrobial therapy, infants with positive blood cultures for B. cereus should undergo lumbar puncture and cranial imaging as soon as possible, followed by long-term neurological follow-up. Strict hand hygiene, regular environmental and equipment disinfection, and appropriate handling of breast milk and formula are important measures to minimize potential healthcare-associated transmission. What is Known: Bacillus cereus is an uncommon but potentially life-threatening cause of late-onset sepsis in preterm infants. Evidence is limited to isolated case reports or small case series, and clinical recognition remains challenging because positive cultures may be interpreted as contamination. What is New: This study reports one of the largest single-center cohorts of hospitalized preterm infants with B. cereus sepsis. An escalation of respiratory support was a prominent observational finding during sepsis onset in this cohort. Our cohort and literature review highlight brain abscess as a severe and potentially underrecognized complication, supporting early cerebrospinal fluid evaluation, serial neuroimaging, and long-term neurodevelopmental follow-up.