Vaccine against <i>Helicobacter pylori</i>: fact or fiction?
Authors: PIERRE MICHETTI
Journal: Gut (1997)

Vaccine against Helicobacter pylori: fact or fiction?Is there a need?Antibiotic-based triple therapy is reasonably eVective in treating patients with symptomatic Helicobacter pylori infection, but this approach is untenable for global control of the infection.In practice, however, anti-H pylori therapy is prescribed to an increasing number of patients, in the absence of proven benefit. 1 2 Firstly, anti-H pylori treatment is increasingly oVered to infected patients with non-ulcer dyspepsia and to asymptomatic carriers.This "test-andtreat" attitude is aimed at controlling the dyspeptic symptoms and at reducing long term risk of gastric malignancies in infected individuals.Secondly, anti-H pylori treatment is also advocated as a first approach in H pylori positive dyspeptic patients, in an attempt to reduce the overall management costs of these patients, without prior endoscopic documentation of the presence of an ulcer or of other complications of the infection. 3 4][8] The increased prescription of antibiotics for H pylori infection has encouraged the emergence of antibiotic resistant strains.Indeed, the eYcacy of current therapies rarely exceeds 90%, and strains isolated after treatment failure often show resistance. 9Resistance to metronidazole is already high in developed countries, and resistance to clarithromycin is increasingly evident.A survey of resistance conducted over five years in Ireland showed that resistance to metronidazole and clarithromycin increased from 32% to 46% and from 5.3% to 8.6%, respectively. 10Because metronidazole has been available for decades before being used against H pylori, this rapid evolution suggests that the selection pressure on H pylori developed once antibiotics were prescribed in association with antisecretory agents.If this speculation is correct, the number of patients treated for H pylori infection may impact directly on the development of resistance, and accumulated treatment failure may result in the enrichment of the human reservoir with resistant strains.A direct impact on the eYcacy of the current treatments may follow 11 12 as evidence suggests that the main reservoir of H pylori is the human stomach.Indeed, passage from animals to humans does not seem to be an important mode of transmission, and H pylori does not resist well in the environment.Alternative strategies are therefore needed to control H pylori infection.There is ample precedent from experience in the control of other infections to suggest that vaccination may be such an alternative, with the advantage of acting regardless of antibiotic resistance.If, in addition, an anti-H pylori vaccine can be used as a treatment, either alone or in conjunction with current treatment, it may help to prevent the emergence of antibiotic resistant strains, preserving the value of antibiotics against this pathogen.Furthermore, if vaccination can prevent and cure H pylori infection, its use in populations with high infection rates in childhood would not depend on prior screening.In this regard it should be noted that the long term persistence of the infection implies that even if some public health action is undertaken on August 22, 2023 by guest.