A 6-Week-Old with Poor Feeding and Lethargy
A 6-week-old exclusively breastfed boy is brought with 2 days of poor feeding, irritability, and one episode of vomiting. Birth weight 3.1 kg, current weight 3.4 kg (below expected). Temperature 38.1 C, HR 180/min, RR 60/min, capillary refill 4 seconds, mottled skin. Anterior fontanelle is full but not bulging. He is drowsy, has a weak cry, and a faint rash on the trunk that does not blanch. Mother had an uncomplicated pregnancy; no maternal fever. He has not received any vaccines.
1. What is your leading diagnosis and which clinical features support it over common alternatives?
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Leading diagnosis: late-onset neonatal sepsis, possibly with meningitis (group B Streptococcus, E. coli, Listeria, or other).
Supporting features:
- Age 6 weeks (late-onset window)
- Non-blanching rash - concerning for meningococcal or disseminated infection
- Shock physiology: capillary refill 4 s, mottling, tachycardia 180, tachypnea 60
- Neurological: drowsy, weak cry, full fontanelle - possible meningitis
- Poor weight gain (3.4 kg at 6 weeks from 3.1 kg birth) suggests chronic poor feeding/underlying issue
- Fever 38.1 C in an infant <3 months is a red flag requiring full sepsis workup
Alternatives considered:
- Bronchiolitis - tachypnea fits but rash, shock, and drowsiness do not.
- Congenital heart disease - could cause poor feeding and shock, but fever and rash point to infection.
- Inborn error of metabolism - possible with poor feeding/lethargy, but fever and rash favor sepsis.
- UTI - common in this age group; must be excluded but doesn't explain rash.
The non-blanching rash plus shock makes this a medical emergency.
2. Describe your immediate management, including investigations and empiric therapy with doses.
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Immediate resuscitation (do not delay for tests):
- Airway/breathing: oxygen, monitor, prepare for possible intubation.
- Circulation: IV/IO access; 20 mL/kg 0.9% saline bolus, reassess, repeat up to 40–60 mL/kg if still shocked; consider inotropes if refractory.
- Glucose: check and treat hypoglycemia (10% dextrose 2 mL/kg).
- Blood cultures before antibiotics if no delay.
Investigations:
- Full septic screen: blood culture, urine (catheter/SPA), CSF (if stable - do not delay antibiotics for LP; treat first if unstable), CBC, CRP, lactate, glucose, U&E, coagulation.
- Consider chest X-ray.
Empiric antibiotics (cover GBS, E. coli, Listeria):
- Ampicillin 50 mg/kg IV q6h (or q8h) plus gentamicin 5 mg/kg IV once daily (or cefotaxime 50 mg/kg q8h if meningitis suspected).
- Adjust to local guidelines and culture results.
Supportive: keep warm, monitor urine output, involve neonatology/PICU. Notify public health if meningococcal suspected; give chemoprophylaxis to close contacts.
Do not send home - admission is mandatory.