Resistance of Helicobacter pylori to macrolides and nitroimidazole compounds. The current situation

Macrolides and nitroimidazoles are among the antibiotics currently used for Helicobacter pylori eradication for which an acquired resistance may occur. Macrolides bind tightly to H. pylori ribosomes and inhibit protein synthesis. Resistance has been found associated with a lack of binding and to a point mutation in position 2058 or 2059 of the 23S ribosomal RNA genes (domain V). This resistance is easy to detect and is clinically relevant. There is a decrease of up to 40% in the success rate of triple therapies including clarithromycin when there is a resistance of H. pylori to this compound. Nitroimidazoles must be reduced to be active on the bacterial DNA. Resistance is associated with a lack of reduction of the NO2 group. But this reduction can be influenced by the redox potential of the environment. The genetic background is not yet known. There are discrepancies between the different methods used to test susceptibility to nitroimidazole; the best method which is now in the process of being standardized, is the agar dilution method. The clinical relevance of this resistance has been questioned. However, despite all the problems highlighted, there is still a difference between strains categorized as susceptible or resistant with regard to the eradication rate of H. pylori. This difference is greater when nitroimidazole is associated with amoxicillin rather than with clarithromycin.