D is the correct answer

This patient is an infant between 29 and 60 days of age with a temperature ≥ 100.4°F (38°C) and a urinary tract infection (UTI) evident on urinalysis. Since the patient is > 28 days of age and has normal levels of inflammatory markers, specifically absolute neutrophil count (ANC) and procalcitonin, American Academy of Pediatrics guidelines recommend oral antibiotics and discharge home. Patients at 29–60 days of age who present with a fever without an evident source of infection should all have a urinalysis, blood culture, and inflammatory markers obtained. The inflammatory markers should include an ANC and procalcitonin level, but if procalcitonin is not readily available, a C-reactive protein (CRP) should be obtained instead.

Abnormal levels of inflammatory markers include an ANC > 4,000/µL and procalcitonin > 0.5 ng/mL, or ANC > 5,200/µL and CRP > 20 mg/L. For this patient, the urinalysis is consistent with a UTI, but the inflammatory marker levels are normal. The urine should be sent for culture to ensure appropriate antibiotic therapy. The patient should be started on oral antibiotics such as cefixime (8 mg/kg per day as a single dose) or cephalexin (50–100 mg/kg four times per day). Discharge home is appropriate as long as the patient can be seen for follow-up in 12–24 hours. For patients with abnormal levels of inflammatory markers, a lumbar puncture (LP) would be considered based on the overall clinical assessment. Unless a patient in this age range has CSF results consistent with meningitis, outpatient treatment is often reasonable, as long as close follow-up is available.

Intravenous antibiotics and hospital admission (A) may be considered if the child appears ill or cannot obtain close outpatient follow-up. However, in this case, oral antibiotics are more appropriate for a well-appearing child with a UTI and otherwise normal findings.

Based on the recommendations from the American Academy of Pediatrics,LP (B, C) is not indicated for an infant at 29–60 days old with an abnormal urinalysis but normal inflammatory marker levels. Additionally, the patient can be sufficiently treated with oral antibiotics and discharged with close follow-up.

References:

1. Pantell RH, Roberts KB, Adams WG, et al. Evaluation and management of well-appearing febrile infants 8 to 60 days old. Pediatrics. 2021;148(2):e2021052228.
2. Rodriguez DM, Nesiama JAO, Wang VJ. Fever and serious bacterial illness in infants and children. In: Tintinalli JE, Ma OJ, Yealy DM, et al., eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw Hill; 2020:(Ch) 119.