In reply: As we mentioned in our article, erythromycin is the drug of choice for treatment and prophylaxis of pertussis in people of all ages.1 Several statements can be made about the use of macrolides in this condition.2

Firstly, erythromycin has been shown to decrease the duration of illness when given early in pertussis infection and to eliminate Bordetella pertussis from the nasopharynx.

Secondly, erythromycin therapy for index cases has been shown to reduce the rate of secondary cases of pertussis in households in uncontrolled studies.3 However, in a recent randomised placebo-controlled study, while erythromycin reduced the incidence of culture-positive pertussis in household contacts there was no reduction in respiratory symptoms.4

Thirdly, clarithromycin and azithromycin have been shown to be at least as effective as erythromycin in treating pertussis in two small comparative studies.5

As Massie et al point out, there are no clinical studies of the use of roxithromycin in this condition, and laboratory in-vitro sensitivity studies suggest roxithromycin may be inferior to erythromycin.

Roxithromycin is the most widely used macrolide in Australia, but it requires a leap of faith and extrapolation to prescribe this drug for prophylaxis or treatment of pertussis. In the one case in our series where roxithromycin was prescribed, this was not our decision. We would have recommended erythromycin on the basis of the available clinical evidence.

Vaccination is preferable to antibiotic prophylaxis for long-term control of pertussis.