Researchers in Canada and the United States have collaborated to discover how strains of ulcer-causing Helicobacter pylori have become resistant to the antibiotic metronidazole.
In genetic analyses, the researchers, from Dalhousie University Medical School in Halifax, Nova Scotia, and Washington University School of Medicine in St Louis, Mo, tracked metronidazole resistance to a mutation in an H pylori gene called rdxA . The gene codes for a nitroreductase enzyme that allows the bacterium to break down organic nitrogen compounds. So, when mutation inactivates the rdxA gene, H pylori cannot break down metronidazole and resistance occurs.
The researchers also reported that the enzyme for which the rdxA gene codes converts metronidazole to hydroxylamine, a mutagen and carcinogen. So, if metronidazole is given alone, the resistant strains won't be eradicated and the sensitive strains could contribute to gastric cancer.
The researchers said their study (in the April 14 Molecular Microbiology. . . [Full Text of this Article]
