The need for a second dose of ceftriaxone in febrile infants age 4-8 weeks.

Objective: To determine if a second intramuscular injection of ceftriaxone was necessary in febrile infants who meet low-risk criteria for outpatient therapy.

Setting: Children's Hospital Emergency Department.

Patients: Febrile infants 4-8 weeks of age.

Methods: Outpatient treatment criteria included non-toxic appearance, no identifiable source for infection on physical examination, CSF WBC > or = 10/mm3, peripheral WBC < or = 15,000/mm3, normal UA, and normal chest radiograph study, if obtained. Additional requirements included a reliable caretaker and re-evaluation in 24 hours. Infants who met these criteria received intramuscular ceftriaxone 50 mg/kg with instructions to follow-up in 24 hours. At the follow-up visit, infants with no identifiable source for infection and negative cultures received a second dose of intramuscular ceftriaxone and were discharged. Cultures were read at 48 hours and at the conclusion of the study. Medical records were reviewed to identify delayed complications.

Results: 172 infants were enrolled. The mean age was 45 days. All CBC, UA, CSF analyses were normal. Chest radiographs were obtained in 56 (30%) infants; all were normal. One (.05%) patient was admitted at the follow-up visit. The mean time to follow-up was 25 hours. Two positive cultures were identified at the re-evaluation visit; one blood culture grew Salmonella and a urine culture grew E. coli. The CSF cultures were all negative at follow-up and remained negative.

Conclusion: Febrile infants 4-8 weeks of age who meet outpatient therapy criteria and have negative cultures and no identifiable source for infection at 24 hours may not require the second dose of intramuscular ceftriaxone.