Induction of beta-lactamase by cefoxitin in anaerobic intestinal microflora

Abstract

Beta-lactamases produced by two anaerobic bacterial strains, Bacteroides ovatus Ax34:1 and Clostridium butyricum NBL3, were shown to be significantly inducible under anaerobic conditions in subinhibitory concentrations of cefoxitin. The induction ratio of beta-lactamase production for Bacteroides ovatus was 2.6 and for Clostridium butyricum 1.6. Incubation of faecal samples with different concentrations of cefoxitin did not result in any induction of beta-lactamase production. When adding a highly inducible aerobic strain (Citrobacter freundii F72:6, induction ratio of 26.5 in broth culture) to faecal samples, an induction ratio of 4.5 was reached. Faeces seem to inhibit beta-lactamase induction in aerobic and anaerobic bacteria. The inducible enzymes produced by the anaerobic strains did not have the same properties as beta-lactamases from aerobic inducible strains, according to substrate profiles and inhibition studies. The results of the present study indicate that increased levels of beta-lactamases in the normal intestinal microflora, which often are observed after administration of beta-lactam agents, are probably due to selection of stably derepressed mutants rather than to induction of beta-lactamase production.

A Case of Pneumococcal Peritonitis after Caesarean Section in a Healthy Woman

“…Identification of the offending organism and determination of definitive antimicrobial treatment are important due to the increasing prevalence of antibiotic resistant strains of Streptococcus pneumoniae . In our case, similar to previous case reports, Ceftriaxone was found efficacious and it should be used, especially in antibiotic resistant strains [ 16 , 23 , 24 ].…”

Effects of treatment with antimicrobial agents on the human colonic microflora

“…Induction of β-lactamases in some aerobic and anaerobic bacteria by cefoxitin has been reported. However, since feces appear to inhibit the induction of β-lactamases, Stark and colleagues (1995) attribute increases in β-lactamases to the selection of “stably derepressed mutants” rather than to β-lactamase induction.…”

“…A combination of omeprazole (20 mg, a proton pump inhibitor for eradication of Helicobacter pylori ) and amoxicillin (1000 mg) twice daily for 14 days resulted in changes in the microflora of the intestinal tract, increases in the numbers of resistant enterobacteria, and an increase in β-lactamase production detected in fecal samples (Stark et al 1995; Adamsson et al 1999). …”

β-Lactamase Production by Oral Anaerobic Gram-Negative Species in Infants in Relation to Previous Antimicrobial Therapy

“…of ␤-lactamase production for both anaerobes and aerobes (17,19). Acute otitis media episodes are especially common during the first year of life (1,22), and they are the main reason for antimicrobial treatment, often recurrent, in early infancy.…”