A 23-Day-Old with Fever and a Bloody Lumbar Puncture
A 23-day-old boy, born at 36 weeks by vaginal delivery with a birth weight of 2.4 kg, is brought to the emergency department with 12 hours of poor feeding and one episode of nonbilious emesis. Rectal temperature is 38.4 °C. He is drowsy but arousable with a weak cry; heart rate 178/min, respiratory rate 62/min, blood pressure 68/40 mmHg, capillary refill 3 seconds, and mottled skin. The anterior fontanelle is soft and flat, and there are no vesicles or rash. The mother reports no history of herpes simplex, no maternal fever, and no group B streptococcus colonisation. Blood glucose is 62 mg/dL. White cell count 18.0 ×10⁹/L with 70% neutrophils and 8% bands. Blood and urine cultures have been sent. Lumbar puncture yields bloody fluid: red cells 12,000/µL, white cells 210/µL with 65% neutrophils, glucose 28 mg/dL, protein 180 mg/dL; simultaneous serum glucose is 90 mg/dL, and the blood has 4.5 ×10⁶/µL red cells and 18,000/µL white cells.
1. What is your first-hour management, including the choice and doses of empirical antimicrobials?
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This is a neonate (under 28 days) with fever, shock and a CSF profile consistent with meningitis - a medical emergency.
Resuscitation: oxygen and cardiorespiratory monitoring; 10–20 mL/kg isotonic crystalloid bolus for the prolonged capillary refill and hypotension, reassessing after each bolus; check and treat hypoglycaemia; keep the baby warm; obtain IV access and a full septic screen including blood culture, urine culture by catheter (not bag), and CSF.
Lumbar puncture: perform it if the baby is stable enough to be positioned; do not delay antibiotics for it. If the baby is unstable or coagulopathic, treat first and tap later - but document that the CSF was not obtained before antibiotics.
Antibiotics: ampicillin plus cefotaxime. For meningitis, ampicillin 100 mg/kg/dose IV every 8 hours, and cefotaxime 50 mg/kg/dose IV every 8–12 hours (adjust to local protocol). Cefotaxime rather than ceftriaxone is preferred in neonates because ceftriaxone displaces bilirubin and is associated with kernicterus. Gentamicin may be added for Gram-negative cover per local protocol.
Acyclovir: add 20 mg/kg IV every 8 hours if there are vesicles, seizures, a maternal HSV history, or unexplained CSF pleocytosis with negative bacterial studies - here the CSF is clearly abnormal, so many units would start it until HSV PCR returns.
Disposition: admit to a neonatal unit; anticipate seizures, SIADH and disseminated intravascular coagulation.
2. The CSF is visibly bloody. How do you interpret the cell count and chemistry, and does the traumatic tap change management?
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A traumatic tap requires correction, but correction is only an estimate and must not be used to dismiss an abnormal result.
Expected white cells from blood contamination: use the blood white-cell-to-red-cell ratio. Here 18,000 white cells per 4.5 ×10⁶ red cells means roughly 1 white cell per 250 red cells. With 12,000 red cells in the CSF, about 48 white cells are attributable to blood, leaving roughly 162/µL - still markedly elevated for a neonate (normal is under about 20–30/µL, and even lower in many reference ranges).
Chemistry is the stronger evidence. A CSF glucose of 28 mg/dL against a serum glucose of 90 mg/dL gives a ratio of 0.31, well below the 0.6 threshold for bacterial meningitis; protein of 180 mg/dL is also high. Blood contamination does raise protein and lowers glucose only slightly, so these values cannot be explained by the tap alone.
Management is unchanged. Treat as meningitis: continue ampicillin plus cefotaxime, add or continue acyclovir pending HSV PCR, and do not stop or narrow antibiotics on the basis of the tap being 'traumatic'. Do not repeat the lumbar puncture immediately; a repeat tap is only useful later to document sterilisation in a baby who is not improving. Note in the chart that correction is approximate - the CSF white count may be over- or underestimated by this method.
3. On day 2 the blood and CSF cultures grow group B streptococcus. How long do you treat, what monitoring is needed, and when would you repeat the lumbar puncture?
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Group B streptococcus with positive CSF means GBS meningitis, not simply bacteraemia - the duration and intensity of treatment are different.
Duration: intravenous therapy for 14–21 days for GBS meningitis (14 days is often sufficient for an uncomplicated course with rapid clinical response and sterile repeat CSF; 21 days for a complicated course). Bacteraemia without meningitis would be 10 days. Keep the baby on ampicillin (or penicillin G once susceptibility is known) for the full course; gentamicin is typically stopped once the CSF is sterile.
Repeat lumbar puncture: perform at 24–48 hours (or after 48–72 hours if the first tap was traumatic or the baby is improving slowly) to confirm sterilisation, and again at the end of therapy if there were complications. Persistently positive CSF mandates longer therapy and imaging.
Monitoring: daily head circumference and fontanelle (ventriculitis, hydrocephalus), seizure watch, sodium for SIADH, cranial ultrasound if there are seizures or a bulging fontanelle, and audiological assessment before discharge because GBS meningitis carries a substantial risk of sensorineural hearing loss. Watch for thrombocytopenia and disseminated intravascular coagulation in the first days.
Follow-up: developmental review at 6–12 months. Counsel the mother that early-onset GBS disease does not contraindicate future vaginal delivery, but intrapartum prophylaxis will be indicated in a subsequent pregnancy.