Neonatal Sepsis with a Positive Blood Culture
A 5-day-old neonate born at 36 weeks' gestation presents with poor feeding, lethargy, and temperature instability (36.2°C). He was born by emergency caesarean section for fetal distress, and maternal vaginal swabs were positive for group B Streptococcus (GBS). He was initially well and discharged on day 2. On admission, his CRP is 45 mg/L, white cell count 3.2 × 10^9/L, and platelets 90 × 10^9/L. Blood culture grows Gram-positive cocci in chains, identified as GBS. Cerebrospinal fluid (CSF) shows 120 white cells/µL (80% neutrophils), protein 1.8 g/L, and glucose 1.1 mmol/L (serum glucose 4.5 mmol/L).
1. Discuss the pathogenesis of early-onset GBS disease and the significance of the CSF findings.
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Early-onset GBS disease occurs when the neonate acquires GBS from the maternal genital tract during labour or delivery. The organism colonises the skin and mucous membranes, then invades the bloodstream, especially if the baby is preterm or has immature immune defences. The neonate's neutrophils are less effective at phagocytosis and killing, and complement activity is low, allowing rapid bacterial proliferation. The CSF findings indicate meningitis: pleocytosis with neutrophil predominance, elevated protein, and low glucose relative to serum. In GBS meningitis, the inflammatory response can cause cerebral oedema, vasculitis, and infarction, leading to long-term neurological sequelae. The low platelet count and low white cell count are markers of severe sepsis and disseminated intravascular coagulation. The judgement is to recognise that GBS sepsis in a neonate can progress rapidly to meningitis and that the CSF findings mandate prolonged antibiotic therapy and close neurological monitoring.
2. Outline your antibiotic and supportive management plan, including duration and monitoring.
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Empirical therapy should cover GBS and other neonatal pathogens (e.g., E. coli, Listeria). A common regimen is intravenous benzylpenicillin plus gentamicin, or ampicillin plus cefotaxime. For GBS meningitis, benzylpenicillin is the drug of choice, often combined with gentamicin for synergy, but gentamicin penetration into CSF is poor; cefotaxime may be added. Duration for GBS meningitis is at least 14–21 days, guided by clinical response and repeat CSF if needed. Supportive care includes maintaining temperature, glucose, and electrolyte balance, and monitoring for seizures. Repeat blood cultures should be negative after 48–72 hours. The platelet count and CRP should be monitored; a rising CRP or persistent thrombocytopenia suggests ongoing infection. The judgement is to balance the narrow-spectrum penicillin for GBS with the need for broad cover until cultures are negative, and to recognise that meningitis requires longer therapy than bacteraemia alone. Hearing tests and developmental follow-up are essential because GBS meningitis can cause sensorineural hearing loss.