Modified Toluidine Blue: an Alternative Stain for Helicobacter pylori Detection in Routine Diagnostic Use and Post-eradication Confirmation for Gastric Cancer Prevention


Background: Modified toluidine blue staining (MTBs) is a simple, inexpensive and time saving method to detect H. pylori in gastric biopsy specimens. As a metachromatic stain, it simultaneously highlights intestinal metaplasia, a gastric cancer precancerous lesion. The aim of this study was to assess the reliability of MTBs compared with hematoxylin-eosin (H&E) for H. pylori detection using immunoperoxidase staining as the gold standard. This technique would be beneficial for a routine diagnosis and confirmation of H. pylori eradication in developing countries where endoscopic-based approaches are dominant. Materials and
Methods: Esophagogastroduodenoscopy with triple site gastric biopsies was undertaken in 207 dyspeptic patients at Thammasat University Hospital, Thailand between 1997 and 1999. H&E, MTBs and immunoperoxidase staining were applied to each specimen. The presence or absence of H. pylori with each stain was interpreted separately and the sensitivity, specificity, positive and negative predictive values of H&E and MTBs were calculated.
Results: A total of 282 specimens from 207 patients were evaluated. Using immunoperoxidase staining, organisms were positive in 117 specimens (41%). MTBs proved almost equally sensitive as immunoperoxidase (99%) and significantly more sensitive than H&E (85%). It has comparable specificity (96% vs 96%), PPV (95% vs94%), and NPV (99% vs 90%) to H&E, using immunoperoxidase staining as gold standard. MTBs compared with immunoperoxidase staining, is cheaper (2 USD vs 12 USD) and faster (20 min vs 16 hrs) compared to immunoperoxidase staining.
Conclusions: MTBs is effective, economical and easy to use in daily practice for the detection of H. pylori in gastric biopsy specimens. In addition to saving time in evaluating H. pylori associated gastritis, with a high sensitivity and ability to demonstrate intestinal metaplasia, the technique may have a rolein confirmation of H. pylori eradication for gastric cancer prevention in a developing country setting.