MODE OF ACTION OF METRONIDAZOLE AND A BACTEROIDES-FRAGILIS META RESISTANCE GENE IN ESCHERICHIA-COLI

The in-vivo mode of action of metronidazole and the MetA protein which confers resistance to metronidazole, was investigated in Escherichia coil wild type and DNA repair-deficient strains. All the E. coil strai ns were moderately susceptible to metronidazole under aerobic conditio ns but were more susceptible under anaerobic conditions, and the amoun t of DNA breakage was less under anaerobic than aerobic conditions. E. coil excision (uvr) and recombination (rec) mutants were more suscept ible than DNA repair wild type strains. Metronidazole did not induce c ell lysis in E. coli but caused single strand DNA breaks in wild type and repair-deficient E. coil strains. The MetA protein reduced DNA bre akage caused by metronidazole in E. coil wild type and DNA repair-defi cient strains grown under aerobic and anaerobic conditions, and inhibi ted the suppressor effect of the RecE protein in E. coil recBC strains . The MetA protein did not inactivate metronidazole.