Neonatal Antibiotic Exposure is Associated With IgE Sensitization in Food Protein Induced Allergic Proctocolitis: A Multicentre Study

To determine the prevalence of immunoglobulin E (IgE) sensitization in infants with food protein-induced allergic proctocolitis (FPIAP)-classically considered a non-IgE-mediated food allergy-and explore the association between early-life factors, particularly neonatal antibiotic exposure, and IgE sensitization.

Infants (0-12 months) with FPIAP were enrolled at two paediatric clinics from January 2020 to April 2025. Diagnosis was confirmed by oral food challenge following food elimination diet. IgE sensitization was defined as positive skin prick tests or suprathreshold serum-specific IgE. Early-life factors including neonatal characteristics and antibiotic exposure, and FPIAP-related variables were considered. Statistical analyses included univariable tests and multivariable Firth's penalized logistic regression.

Among 112 infants recruited (median age at onset 3.0 months [IQR 1.8-4.7]; 54.5% males), cow's milk was the culprit food in all cases and IgE sensitization occurred in 17 (15.2%) cases. Neonatal antibiotic exposure occurred in 21/112 (18.8%) infants and was associated with increased odds of IgE sensitization (OR 8.11, 95% CI 2.21-32.32; p = 0.002), remaining significant after multivariable adjustment.

In this exploratory study, neonatal antibiotic exposure was associated with increased likelihood of IgE sensitization in FPIAP. These hypothesis-generating findings warrant prospective studies to confirm the association and investigate its underlying mechanisms and long-term allergic outcomes.