one hundred and eighty fresh clinical isolates of haemophilus influenzae , comprising 74 ampicillin-susceptible , beta-lactamase negative , and 106 ampicillin-resistant , beta-lactamase positive , strains , were tested for their susceptibility to erythromycin , roxithromycin , sulphamethoxazole , erythromycin-sulphamethoxazole and roxithromycin-sulphamethoxazole in a fixed ratio of 1:19 .
C0014806
erythromycin
C0035891
roxithromycin