Serratia marcescens Bloodstream Infections in a Neonatal Intensive Care Unit: A Retrospective Case Series From Rabat,...

Background Serratia marcescens is an opportunistic Gram-negative bacillus increasingly implicated in neonatal intensive care unit (NICU) infections and severe neonatal sepsis, particularly among preterm infants. Methods We conducted a retrospective observational case series in the NICU of Mohammed V Military Teaching Hospital, Rabat, Morocco, between August 2024 and August 2025. Neonates with at least one positive blood culture for S. marcescens associated with clinical signs of sepsis were included. Clinical, laboratory, microbiological, imaging, therapeutic, and outcome data were analyzed. Results Sixteen neonates were identified; 12/16 (75.0%) were born before 34 weeks of gestation, and 9/16 (56.3%) had a birth weight below 1,500 g. Respiratory distress and hemodynamic instability were the predominant clinical manifestations. Thrombocytopenia (platelet count <50,000/µL) was observed in 6/16 (37.5%) neonates, and elevated C-reactive protein (CRP) levels were frequent. Cranial ultrasonography was normal in most patients; grade I intraventricular hemorrhage was identified in 5/16 (31.3%). One neonate developed multiple contrast-enhancing brain lesions on magnetic resonance imaging (MRI), consistent with multifocal brain abscess formation. All patients received empirical broad-spectrum antibiotic therapy, subsequently adjusted according to antimicrobial susceptibility testing. Overall mortality was 7/16 (43.8%). Conclusion This single-center case series demonstrates the potential severity of S. marcescens bloodstream infection in hospitalized neonates. The high observed mortality highlights the importance of timely microbiological diagnosis, susceptibility-guided treatment, and rigorous infection-prevention surveillance. Molecular typing and structured outbreak investigations are warranted when temporal clustering is suspected.