Abstract
Ceftazidime (CAZ, SN 401) showed high antibacterial activity against most of anaerobic bacteria except for the strains of β-lactamase producing Bacteroides fragilis group and Fusobacterium varium, Fusobacterium mortiferum, Eubacterium lentum and Clostridum difficicile. The activity of CAZ against recent clinical isolates was as strong as that against the standard strains.
When the bacteria were serially subcultured in the drug-contained medium, resistance was increased step by step, but the increasing rate of the resistance to the drug was higher in non β-lactamase producing B. fragilis than in β-lactamase producing B. fragilis.
CAZ was less stable to β-lactamase produced by B. fragilis than cefbuperazone (T-1982) and cefotaxime (CTX) but more stable thar cefazolin (CEZ), cefoperazone (CPZ) and cefpiramide (CPM).
In the protection test against the experimental intraperitoneal infections with B. fragilis in mice, CAZ was inferior to cefmetazole (CMZ) and comparable to CPZ when the challenge organisms were β-lactamase producing ones. When the challenge organisms were non β-lactamase producing ones, however, CAZ showed high elimination effects, comparable to those of CMZ, even in the small dose groups. The bacterial elimination efficacy of CAZ in the kidney, in particular, was stronger than that of CMZ.
Increase of C. difficile by CAZ in cecum of mice was only minor.
