Abstract
The in-vitro activities of 16 antimicrobial agents were tested against 57 strains of Haemophilus ducreyi isolated in Amsterdam during an eight year period. The susceptibility patterns of the isolates from different years were compared. In the first four years more than 30% were β-lactamase negative and showed MICs for tetracycline of 2 mg/l or less. From 1982 to 1985 all strains, except one, produced β-lactamase and were tetracycline resistant. Furthermore, MICs for cefotaxime, sulphamethoxazole and trimethoprim increased. No changes were seen with cephradine, erythromycin, kanamycin, gentamicin, chloramphenicol, nalidixic acid, pipemidic acid, norfloxacin, pefloxacin or ciprofloxacin.