Helicobacter pylori is a pathogenic bacteria transmitted from individual to individual, being
scientifically recognized as an agent who causes persistent inflammatory activity on the
gastric mucosa. This pathogen represents a Global Health problem, as shown in a systematic
review by Hooi et al. Besides regional differences, more that half of the world population is
expected to have already been infected by this bacteria.
In Portugal, research studies estimate that more than 80% of the adult population has already
contacted with H. pylori.
H. pylori infection is associated with active chronic gastritis in every colonized patient,
what may consequently lead to peptic ulcer disease, atrophic gastritis, gastric
adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma.
For that reason, H. pylori infection is considered to be a disease, independently of the
presence of gastrointestinal symptoms. Additionally, H. pylori has been classified as a
confirmed carcinogen (class I) by the International Agency for Research, being responsible
for carcinogenic pathways conducting to both gastric adenocarcinoma and lymphoma. This fact
gains a particular relevance taking into account that gastric cancer is one of the most
prevalent cancers worldwide. On other hand, more than 75% of the gastric cancers occur
following H. pylori infection.
Thus, H. pylori eradication constitutes an essential Public Health measurement, being
inclusively considered a cost-effective method to decrease the gastric cancer burden, by
promoting pre-malignant lesions regression, such as atrophic gastritis, and by delaying the
disease progression in case of intestinal metaplasia or dysplasia.
Maastricht V consensus is a document updated in 2016, including the major recommendations
regarding H. pylori diagnosis, follow-up and treatment. It highlights the emergence of
antibiotic resistances and how they must influence clinical practice, namely the choice of
antibiotic regimens, as successful eradication has become less frequent with more prevalent
antibiotic resistances. This is the case of clarithromycin and metronidazol, both currently
recommended as first-line options by the Portuguese Society of Gastroenterology. In fact, a
systematic review conducted in 2018, aiming to evaluate antibiotic resistances on the
Portuguese population observed that clarithromycin, metronidazole and double resistance
occurred in 42%, 25% and 20% of the individuals, respectively.
Nowadays, Maastricht V guidelines recommend quadruple regimens containing bismuth, such as
Pylera (r), as the first-line option in areas with significant double resistance to
metronidazole and clarithromycin. Another option currently being investigated is the double
therapy with amoxicillin in high doses and proton pump inhibitor. This has become a
particularly attractive alternative due to its efficacy, good tolerability and significantly
low resistance (<1%) among the European population.
The aim of this clinical trial is to compare both regimens - pylera (r) and high-dose
amoxycillin - in H. pylori eradication, regarding their efficacy, tolerability and side
effects, in order to asses viable therapeutic options in a population with progressively
increasing resistances to alternative regimens currently recommended.