What is the first-line treatment for pertussis in a patient diagnosed within the first 7 days?

For a patient diagnosed with pertussis within the first 7 days, the first-line treatment is azithromycin. The use of antibiotics in the early stages of pertussis can significantly reduce the severity of the disease and the duration of the contagious period. Azithromycin is particularly favored due to its efficacy, tolerability, and ease of administration in pediatric patients.

When initiated early, generally within the first week of illness, macrolide antibiotics such as azithromycin effectively eradicate the Bordetella pertussis organism from the nasopharynx, thereby minimizing transmission and helping to alleviate symptoms. The treatment targets a critical phase in the disease, as early antibiotic intervention can help prevent further complications such as severe coughing fits and associated complications.

While erythromycin is also a suitable antibiotic choice for treating pertussis, azithromycin is more commonly recommended due to its more favorable side effect profile and simpler dosing regimen. Trimethoprim-sulfamethoxazole is indicated for patients who cannot tolerate macrolides but is not the first-line treatment for pertussis. Supportive care alone would not address the bacterial infection or reduce transmission, making antibiotic treatment essential during the early stages of the disease.