Escherichia coli and Bacteroides fragilis are common copathogens in clinical intra-abdominal sepsis, yet it is unclear how they interact synergistically in vivo. We sought to determine whether E. coli and B. fragilis, in combination but not alone, could exert a detrimental effect on the peritoneal host defenses of translymphatic absorption and bacterial phagocytosis. Our data indicated that non...

The role of cell-free soluble factors (lymphokines) derived from mitogen-activated splenic cells of mice previously immunized against Bacteroides fragilis was evaluated in the treatment of B. fragilis intra-abdominal abscess (IAA). Neither clindamycin nor lymphokines alone were effective against an established B. fragilis IAA, but the combination of clindamycin and lymphokines decreased the abs...

We have studied the antimicrobial action of metronidazole against Bacteroides fragilis and Escherichia coli both in pure cultures and in combination. Concentrations of metronidazole above the minimal inhibitory concentration (MIC) produced a marked bactericidal effect on B fragilis at six hours. E coli however showed only a slight and transitory decrease in population when exposed to concentrat...

Athymic mice formed significantly smaller abscesses than euthymic mice in response to the intraperitoneal inoculation of an abscess-inducing mixture of Escherichia coli, Bacteroides fragilis, and autoclaved colonic contents, an abscess-potentiating agent. Adoptive transfer of nonimmune, Thy-1-positive spleen cells to athymic mice restored their ability to make abscesses of sizes similar to thos...

The inhibitory effect of Bacteroides fragilis on the in vitro killing of Escherichia coli by polymorphonuclear leucocytes was studied with two pairs of E coli and B fragilis isolated from human wound infections. Both B fragilis strains behaved similarly: they inhibited the killing of one E coli strain, while the killing of the other E coli strain was not affected. The different behaviour of the...

Two members of the Bacteroides fragilis group, B. ovatus and B. thetaiotaomicron, are difficult to distinguish by biochemical methods. They are currently identified on the basis of their variable ability to ferment salicin. We studied a method of identification for these two species by using cell lysis by bacteriophages. A total of 38 bacteriophages were used to distinguish the two species. Ide...

Clavulanic acid reduced the MICs of amoxicillin, carbencillin , cefamandole, cefotaxime, ceftazidime, ceftizoxime, cephalothin, and penicillin G, but not of cefoxitin or moxalactam, against 77 isolates of the Bacteroides fragilis group, all rapidly beta-lactamase positive by the nitrocefin slide test. It had no effect on the susceptibilities of eight Bacteroides distasonis strains that were slo...