What is the appropriate management for a febrile 3-week-old infant who appears non-toxic?

In the case of a febrile 3-week-old infant who appears non-toxic, the appropriate management involves a thorough evaluation to rule out serious infections, given the high risk of bacteremia or meningitis in this age group. The infant's age places them in a vulnerable category where even mild symptoms can signify significant underlying conditions.

The correct answer includes the steps of admitting the infant, obtaining urine, blood, and cerebrospinal fluid cultures, and starting intravenous antibiotics. This approach is crucial because:

1. High Risk for Serious Infections: Infants under 30 days are at increased risk for serious bacterial infections, such as urinary tract infections, sepsis, and meningitis. Immediate evaluation and treatment reduce morbidity and mortality associated with these conditions.

2. Comprehensive Work-Up: Performing cultures (blood, urine, and CSF) is essential to identify the causative organism. Early diagnosis and appropriate antimicrobial therapy are critical in managing infections in young infants effectively.

3. Intravenous Antibiotics: Immediate initiation of IV antibiotics is warranted since waiting for culture results can delay appropriate treatment. Bacterial infections can progress rapidly in young infants, and empirical treatment based on current guidelines is standard practice.

This management aligns with clinical