Effect of erythromycin and amoxycillin on Bordetella pertussis in the nasopharynx.

The effectiveness of oral erythromycin and amoxycillin in eradicating Bordetella pertussis from the nasopharynx was compared. Erythromycin in a dosage of 40--50 mg/kg/day was significantly more effective than amoxycillin in a dosage of 25--30 mg/kg/day. The organism did not disappear in three cases receiving a lower dosage of erythromycin. As antibiotic treatment does not affect the clinical course of fully-developed whooping cough, erythromycin is indicated primarily when particularly susceptible individuals are threatened by exposure. In such cases erythromycin should be given as soon as whooping cough is suspected.