RESUMO
OBJECTIVE: To evaluate the impact of a standardized allergy-guided approach to Group B Streptococcus (GBS) prophylaxis in pregnant women with reported penicillin or cephalosporin allergy. METHODS: This interrupted time-series analysis included obstetric patients requiring GBS prophylaxis who reported penicillin or cephalosporin allergies. Patients were divided into baseline (April 1, 2019 to July 21, 2020) and intervention (July 22, 2020 to July 31, 2021) groups. The primary outcome was prophylaxis appropriateness, based on antibiotic type, nature of reaction, and cross-reactivity risk. Secondary outcomes included type of prophylaxis received and antibiotic-related adverse events. RESULTS: The study included 88 patients in the baseline period and 52 patients in the intervention period. Appropriate prophylaxis increased from 47% (41/88) to 85% (44/52), with the segmented regression model confirming a statistically significant increase over time (incidence rate ratio 1.57; 95% CI 1.02-2.43, P = 0.04, slope coefficient 1.06/month; 95% CI 1.01-1.10, P = 0.01). Penicillin and cefazolin use increased from 61% (54/88) to 87% (45/52) in the intervention period (P = 0.002), and no hypersensitivity reactions occurred during this period. CONCLUSIONS: Implementation of standardized allergy-guided prophylaxis safely improved appropriate ß-lactam antibiotic use in obstetric patients requiring GBS prophylaxis who reported penicillin and cephalosporin allergies.