Intracellular redox status and antibiotic resistance in enterogastric micro-aerophilic bacteria: evidence for the 'scavenging of oxygen' hypothesis.

Metronidazole and glutathione reduction activities were measured in situ in the micro-aerophilic bacteria Campylobacter coli and Helicobacter pylori employing 14N- and 1H-nuclear magnetic resonance spectroscopy. The properties of these enzyme activities were investigated in matched pairs of strains with sensitive and resistant phenotypes to the antimicrobial metronidazole. The results indicated that the ability of each type of strain to reduce metronidazole corresponded to its sensitive or resistance phenotype. Higher levels of glutathione reduction and a significantly lower Ki for metronidazole were observed in sensitive strains compared to resistant strains. These findings suggested a relationship between the cellular machinery regulating intracellular redox status in C. coli and H. pylori, and the effects of metronidazole on these bacteria, which supported the 'scavenging of oxygen' hypothesis.