Successful azithromycin desensitization using a modified protocol after initial reaction: A pediatric case report.

Pertussis is a highly contagious infection associated with significant morbidity and mortality in young infants despite widespread vaccination programs. Early recognition and treatment are important to reduce disease severity, shorten symptom duration, and limit transmission. We report the case of a 51-day-old previously healthy boy who presented with a 4-day history of whooping cough, apnea, circumoral cyanosis, post-tussive emesis, and reduced oral intake. Pertussis was confirmed by a nasopharyngeal respiratory multiplex PCR panel detecting Bordetella pertussis. The patient initially received two doses of oral azithromycin (10 mg/kg/dose); however, approximately 20-30 min after the second dose, he developed facial puffiness and lip swelling consistent with a probable immediate hypersensitivity reaction. This complicated management because alternative antimicrobial agents, including trimethoprim-sulfamethoxazole and fluoroquinolones, were considered unsuitable owing to age-related safety concerns and limited clinical applicability. Following multidisciplinary evaluation and individualized risk-benefit assessment, azithromycin desensitization was undertaken. The initial desensitization attempt was discontinued because of recurrent hypersensitivity symptoms, prompting modification of the protocol. A second desensitization attempt using extended infusion and observation intervals was successfully completed. Following tolerance of intravenous azithromycin, the patient was transitioned back to oral therapy and completed the full 5-day treatment course without recurrence of hypersensitivity symptoms or delayed reactions. His cough gradually improved, and apnea episodes resolved before discharge. This case highlights azithromycin desensitization as a potential individualized therapeutic strategy in carefully selected infants with pertussis and suspected macrolide hypersensitivity when safer alternative treatment options are limited. Further evidence is required before broader conclusions regarding safety, efficacy, and reproducibility can be drawn.