Activity of ceftizoxime and comparative compounds against Bacteroides fragilis in a mouse model of anaerobic infection.

A new mouse model of anaerobic infection with Bacteroides fragilis alone or in a mixed infection with Escherichia coli is described. It is established by implantation under the skin of a filter paper disk saturated with the appropriate bacterial suspension. The penetration of antibiotics into the implantation site can be detected by assaying the disk. The local infection can be both standardized and evaluated by determining the bacterial count on the disk. The antimicrobial efficacy of ceftizoxime was compared with other commercially available antibiotics administered in a single dose, 40 mg/kg subcutaneously, one hour after implantation of the disk. Using such a regimen ceftizoxime was found to be superior to a clindamycin-gentamicin combination and equal to or superior to cefoxitin in these models.