Pruebas Genéticas para el Tratamiento Helico Bacter Pylori

Helicobacter pylori is a bacterium associated with a number of gastrointestinal problems, such as peptic ulcers, chronic gastritis, and stomach cancer. Eradication of Helicobacter pylori has proven beneficial for numerous conditions. Currently, multiple treatment methods are available for Helicobacter pylori infection. These include proton pump inhibitors (polyphosphoinositides [PPIs]) to suppress acid production, in combination with antibiotic therapy consisting of one or more agents such as amoxicillin, clarithromycin, or metronidazole. This first-line treatment protocol generally achieves eradication in 70% to 90% of cases. Differences in the degree of eradication depend on the regimen used and the patient population treated. Treatment failures are frequently attributed to antibiotic resistance or poor patient compliance. Clarithromycin resistance is an important factor associated with treatment failure, with 13% of Helicobacter pylori strains shown to be resistant to this antibiotic. There are genetic factors that influence the treatment of H. pylori through PPI metabolism. Individuals with polymorphisms in the CYP2C19 gene, a component of cytochrome P450 (CYP450), metabolize PPIs more slowly than normal. Genetic variations in the CYP450 enzyme system have been among the most studied in the field of pharmacogenomics. This enzyme family is found in the liver and is responsible for metabolizing and eliminating a large number of pharmacological substances. Differences in PPI metabolism lead to variability in gastric acid suppression, which in turn leads to variability in gastric pH and a potential impact on treatment efficacy. Observations suggest that patients who are high metabolizers of PPIs have lower H. pylori eradication rates with standard treatments compared to low metabolizers. Polymorphisms in the CYP2C19 gene are common and vary with ethnicity. Patients without the CYP2C19 polymorphism do not show a reduction in their ability to metabolize PPIs. These patients are known as extensive metabolizers. The heterozygous polymorphism is found in 27%–37% of the Caucasian population and 46%–50% of the Asian population. These patients clear PPIs from circulation much more slowly and are known as poor users. In patients treated with proton pump inhibitors (PPIs), intragastric pH correlates with CYP2C19 status. Patients homozygous for CYP2C19 exhibit a less acidic intragastric pH compared to patients without the CYP2C19 mutation. Intragastric pH has implications for the treatment of H. pylori. H. pylori is more sensitive to antibiotics at less acidic pH levels. These less acidic levels promote greater stability and bioavailability of antibiotics. Therefore, H. pylori treatment is expected to be more effective when maximum gastric acid suppression and higher pH levels are achieved. It is proposed that treatment should be pharmacogenomically based and individualized according to CYP2C19 gene status. If this is known before treatment, adjustments can be made to PPI selection and antibiotic dosages to achieve optimal gastric acid suppression in all patients. The FDA has approved a commercial genetic test, the Roche AmpliChip Cytochrome P450 Genotyping test, which examines polymorphism in the CYP2D6 and CYP2C19 isoenzymes of the cytochrome P450 enzyme system. <a id="