Antibiotic Use in Bronchiolitis in a Latin American Neonatal Cohort (2010–2025): A Descriptive Multicenter Study with Comparison to International Cohorts

Background: Antibiotic use in bronchiolitis is generally discouraged by international guidelines, given that concurrent bacterial superinfection is uncommon. Reported prevalence varies widely across countries and settings, with no prior comparable data for Latin American neonatal units.Objective. To describe, for antimicrobial stewardship surveillance, the prevalence of documented antibiotic use during bronchiolitis episodes in a Latin American neonatal cohort (2010–2025) not explained by an identifiable alternative reason, and to place it in context against the international literature.Methods. Descriptive, retrospective, multicenter study. Bronchiolitis episodes were identified through free-text searching of the diagnosis field. An antibiotic exposure window was defined from one day before to 20 days after diagnosis. Every case with documented antibiotic use underwent manual case-by-case review, cross-referencing treatment duration (≤3 documented days = unconfirmed suspicion) against other recorded diagnoses to identify reasonable alternative reasons for use, distinct from bronchiolitis itself. Sites were randomly pooled into 6 anonymized groups.Results. 685 bronchiolitis episodes were identified; 19 (2.8%) were excluded for infection documented at diagnosis, leaving 666 analytic episodes. Documented antibiotic use was observed in 48 episodes (7.2%; 95% CI 5.5–9.4%). After manual review, 28 of 48 (58%) had an identifiable alternative cause, leaving 20 episodes (3.0%; 95% CI 2.0–4.6%) without one. Group 5 showed the highest relative prevalence (33.3%; 7/21). No significant baseline differences were found between exposed and unexposed infants. One death occurred among all 685 episodes, in a case excluded for concurrent infection (685 g, 26 weeks, group B Streptococcus sepsis); no deaths occurred within the analytic cohort (0/666).Conclusions. Documented antibiotic use in bronchiolitis without an identified alternative cause in this Latin American cohort (3.0%) is considerably lower than reported in most international literature (typical ranges 13%–55%). Nearly 60% of crude antibiotic use is explained by causes other than uncomplicated bronchiolitis, underscoring the importance of individual case review over administrative records alone.