Objective: To evaluate the diagnostic performance of different staining methods for Helicobacter pylori (H. pylori) in patients treated with proton pump inhibitors (PPI) Material and Methods: This is a retrospective study involving 75 gastric biopsies from patients with and without PPI therapy between October 2018 and September 2019. Slides were stained with hematoxylin and eosin (H&E); Giemsa and immunohistochemical staining (IHC) was done using polyclonal anti-H. pylori antibodies.

more »

... analysis was performed to determine any association between the results of different staining methods and PPI consumption. Sensitivity, specificity and positive-negative predictive values of H&E and Giemsa stains were calculated. Results: Overall, H. pylori infection was detected in 33.3% of patients using IHC, 26.7% using H&E, and 28.0% via Giemsa staining. A strong correlation was found between PPI consumption and low H. pylori density detected via IHC (p-value=0.015) but not using H&E and Giemsa staining. The sensitivity of H&E and Giemsa was markedly reduced as a result of PPI consumption (57.1% to 18.2% vs. 85.7% to 27.3%, respectively). Conclusion: Identification of H. pylori using IHC in patients treated with PPI was superior to H&E and Giemsa stains. Both H&E and Giemsa stains showed a marked decrease in sensitivity in patients receiving PPI. The results indicate that IHC should be performed in patients with PPI therapy instead of H&E or Giemsa stains, and PPI should be discontinued for at least 14 days before the performance of endoscopy.