In vitro activity of two beta-lactam antibiotics against strains of the Bacteroides fragilis group isolated from humans and from Callithrix penicillata marmosets.

The purpose of this study was to determine the in vitro activity of cefoxitin and imipenem against strains of the Bacteroides fragilis group isolated from the intestinal tract of humans and Callithrix penicillata marmosets. The majority of the human and marmosets B. fragilis strains was resistant to cefoxitin. The percentages of resistance to cefoxitin among B. fragilis marmoset strains were higher than those of human origin. On the other hand, the majority of the other Bacteroides of the B. fragilis group isolated from human and marmosets were susceptible to this drug. Imipenem was the most effective beta-lactam drug in this study, and we detected no resistance.