The discovery that Helicobacter pylori infection is the main cause of most gastroduodenal diseases has been a major breakthrough in gastroenterology. It has dramatically changed the management of these diseases which are now considered as infectious diseases and are treated with antibiotics.

Triple therapy, including two antibiotics, amoxicillin and clarithromycin, and a proton pump inhibitor given for a week has been recommended as the treatment of choice at several consensus conferences.^1–6 However, this treatment may fail for several reasons, as reported elsewhere.⁷ In fact, the main reason for failure was found to be H pylori resistance to one of the antibiotics used (that is, clarithromycin). Other treatments have also been proposed, including metronidazole, a drug for which resistance is also a problem although to a lesser extent, as well as tetracycline, fluoroquinolones, and rifamycins for which resistance has become an emerging issue.^8,9

Our aim was to review the prevalence of H pylori resistance to these various antibiotics, their clinical importance, and methods of testing, especially in light of the resistance mechanism which allows application of molecular methods.

PREVALENCE OF H PYLORI RESISTANCE TO ANTIBIOTICS

Numerous studies have been performed to determine the prevalence of H pylori resistance to antibiotics. However, many of them have drawbacks, in particular concerning the number and representativeness of the strains tested.

Most of the studies were performed in specialised centres, with recruitment of special cases which are not always representative of patients as a whole and, because these studies are monocentric, the number of patients may be low, leading to wide confidence intervals of the prevalence rates obtained.

Ideal studies involving patients who are representative of a given region are few. An alternative has been to analyse prevalence data obtained from clinical trials aiming to evaluate new regimens. As prevalence is in essence an evolving phenomenon, only …