The importance of P-glycoprotein multidrug transporter activity measurement in patients with Helicobacter pylori infection.

P-glycoprotein is important in local antibiotic resistance. Aim was to evaluate the role of P-glycoprotein in local antibiotic resistance in patients with antral gastritis during antibiotic therapy to Helicobacter pylori infection. In the group of 53 patients with pathohistologically verified gastritis and microbiologically confirmed H. pylori infection (no signs of antimicrobial resistance) we have determined P-glycoprotein activity in gastric mucosa biopsy specimens, and compared them with the P-glycoprotein activity in 12 control subjects with normal endoscopic findings. The H. pylori positive patients were treated according to Maastricht protocol with short-term 7-day therapy consisting of two antibiotics (amoxicillin and azithromycin/metronidazole and clarithromycin) and a proton pump inhibitor P-glycoprotein activity was determined in rhodamine dye efflux test and quantified by ratio of the mean fluorescence (RMF) in flow cytometry analysis. H. pylori was successfully eradicated in the first cycle in 20 patients, whereas therapy was continued in 33 patients. The mean pre-treatment RMF values were higher in patients with H. pylori infection then in control subjects (p < 0.0046). RMF was also higher in patients with multiple therapeutic failure than in those with successful H. pylori eradication (p < 0.0001). RMF increased significantly during the antibiotic therapy (p < 0.05). P-glycoprotein might be one of the causes of therapy failure in patients with H. pylori. Our study confirms the importance of quantitative evaluation of P-glycoprotein expression during antibiotic treatment response.

Increased activity of Pgp multidrug transporter in patients with Helicobacter pylori infection.

AIM: To determine whether local antibiotic resistance involves P-glycoprotein (Pgp)-mediated active drug out-pumping during Helicobacter pylori (H pylori) infection treatment with classic antibiotic therapy. METHODS: Pgp activity was determined in gastric mucosa biopsy specimens obtained from 53 patients with pathohistologically verified gastritis and microbiologically confirmed H pylori infection, and compared with the Pgp activity in 12 control subjects with normal endoscopic findings. The H pylori positive patients were treated with short-term 7-d therapy consisting of two antibiotics (amoxicillin and azithromycin/metronidazole and clarithromycin) and a proton pump inhibitor. Pgp activity was determined by flow cytometry in the test of rhodamine dye efflux and quantified as mean fluorescence ratio (RMF). RESULTS: Upon the first cycle, H pylori was successfully eradicated in 20 patients, whereas therapy was continued in 33 patients. In the course of antibiotic therapy, RMF increased (P<0.05) and gastric cells showed higher rhodamine dye efflux. The mean pre-treatment RMF values were also higher (P<0.0001) in patients with multiple therapeutic failure than in those with successful H pylori eradication and control subjects. CONCLUSION: Pgp might be one of the causes of therapy failure in patients with H pylori and antibiotic therapy could be chosen and followed up on the basis of the Pgp transporter local activity.