Inactivation of cefoxitin and moxalactam by Bacteroides bivius beta-lactamase

Abstract

Moxalactam and cefoxitin are known for their high stability against Bacteroides I-lactamases. We investigated the I8-lactamase activity of crude extracts obtained from three strains of Bacteroides bivius and two strains of Bacteroides fragilis against cefoxitin and moxalactam. In a spectrophotometric antibiotic assay with a 24-h incubation period, B. bivius extracts decreased the initial concentration (10 p,g/ml) of moxalactam and cefoxitin by 60%, whereas B. fragiis extracts had no effect. In a microbiological assay, when B. bivius or B. fragilis extracts were added to cephalothin (10 ,ug/ml) or cefamandole (4 ,ug/ml), we observed complete disappearance of the inhibitory zones against the indicator strain (Clostridium perfringens ATCC 13124). Only the B. bivius extracts were able to decrease the inhibitory activity (from 10 to 100%) of cefoxitin and moxalactam (each at 10 ,ug/ml). Prior addition of clavulanic acid to crude extracts prevented the losses of antibacterial activity. Furthermore, the inhibition of the j8-lactamase hydrolysis of nitrocefin by cefoxitin or moxalactam was prevented by a 12-h preincubation of the I-lactam with the B. bivius extracts but not with the B. fragilis extracts. Finally, with the B. bivius strain producing the most j8-lactamase, we showed an effect of inoculum size on the MICs of cefoperazone, cefoxitin, and moxalactam with a broth dilution technique. Increasing the inoculum size with the B. fragilis strains had no effect on the MICs of cefoxitin and moxalactam. These results indicate a slow and clavulanate-sensitive ,-lactamase activity of B. bivius extracts against cefoxitin and moxalactam.

Beta-lactamase production and susceptibilities to amoxicillin, amoxicillin-clavulanate, ticarcillin, ticarcillin-clavulanate, cefoxitin, imipenem, and metronidazole of 320 non-Bacteroides fragilis Bacteroides isolates and 129 fusobacteria from 28 U.S. centers

“…Other recent studies did not find any penicillin-resistant fusobacteria in 31 strains studied (7,16,23 ,ug/ml. Our findings confirm previous reports of susceptibility to these agents (3,9,12,18,19,23,30 The results of the current study emphasize significant rates of P-lactamase production in non-B. fragilis Bacteroides species and fusobacteria and indicate the need for 1-lactamase testing of these isolates.…”

“…fragilis group anaerobic gram-negative rods has undergone gradual change (2,28). ,-Lactamase production has been reported for several non 19,26,29,30). ,B-Lactamase positivity has also recently been described in fusobacteria, notably, Fusobacterium nucleatum (5,31 32 ,ug/ml; 9 of these 10 isolates were ,-lactamase positive.…”

Molecular analysis of the effector mechanisms of cefoxitin resistance among Bacteroides strains

“…Specific cefoxitinase assays were carried out as described by Malouin et al 27 Chromosomal DNA preparation, restriction endonuclease treatment, PCR and Southern hybridization Regular restriction endonuclease digestions were performed in a volume of 20 mL with 0.2-1 mg of DNA under the conditions recommended by the suppliers. PCR reaction mixtures (usually either 20 or 50 mL) contained half volumes of 2× ReadyMix PCR reaction mix (Sigma), 0.7 mM primers, 1/10 volume of template DNA and sterile water supplemented to the indicated final reaction volume.…”

Characterization of beta-lactamases from non-Bacteroides fragilis group Bacteroides spp. belonging to seven species and their role in beta-lactam resistance

“…fragilis group Bacteroides species (22,41,50). Malouin et al (26), using a spectrophotometric method with a 24-h incubation period, have described slow hydrolysis rates of cefoxitin and moxalactam by B. bivius. This method was not used in the current study.…”

“…buccae, B. oralis, B. splanchnicus, B. coagulans, B. ureolyticus, Mitsuokella multiacida, and Megamonas hypermegas (3, 5, 18, 22, 26, 29-31, 37, 41, 42, 44, 46, 50, 51). Apart from a few studies with B. bivius, B. disiens, B. oralis, and black-pigmented Bacteroides spp., however, no systematic study of the characteristics of ,-lactamases in these organisms has been undertaken (22,26,30,31,41,42,46,50,51).…”