Respiratory Viral Positivity, C-Reactive Protein Levels, and Lumbar Puncture and Antibiotic Use in Well-Appearing Febrile Infants ≤ 60 Days.

AIM: To describe lumbar puncture (LP) and antibiotic use according to respiratory viral status and C-reactive protein (CRP) level in well-appearing febrile infants aged ≤ 60 days. METHODS: We conducted a single-centre retrospective study of well-appearing febrile infants aged ≤ 60 days who underwent respiratory viral testing. The primary outcome was LP at any time during hospitalisation. Secondary outcomes included antibiotic treatment and joint patterns of LP and antibiotic use. Analyses were stratified by age (≤ 21, 22-28, and 29-60 days) and by a CRP threshold of 2.0 mg/dL. RESULTS: Among 204 febrile episodes in 203 infants, 82 (40.2%) were virus-positive. LP was less frequent in virus-positive than virus-negative episodes (1.2% vs. 12.3%; p = 0.003), as was antibiotic treatment (4.9% vs. 43.4%; p < 0.001). Among infants aged ≤ 21 days, neither LP nor antibiotics were used in the 12 virus-positive episodes, compared with 6/32 and 16/32 virus-negative episodes, respectively. Among virus-positive episodes with CRP < 2.0 mg/dL, 0/77 underwent LP and 2/77 received antibiotics. CONCLUSIONS: LP and antibiotic use were less frequent among virus-positive episodes and differed across age and CRP strata. These unadjusted findings describe real-world management patterns and do not establish the safety of deferring LP or antibiotics.