In situ hybridization for Helicobacter pylori in gastric mucosal biopsy specimens: Quantitative evaluation of test performance in comparison with the CLOtest and thiazine stain

Numerous detection methods for Helicobacter Pylori (H. pylori) have been developed with varying degrees of purported diagnostic utility. We have developed a rapid nonradioactive in situ hybridization (ISH) method for H. pylori detection in paraffin-embedded tissue and assessed its relative diagnostic performance by receiver operator characteristics (ROC) in comparison to the thiazine stain and CLOtest. Forty-five patients undergoing endoscopy had antral biopsies and concomitant CLOtest performed. ISH for H. pylori was done using a 22-base, biotin-labeled oligonucleotide probe complementary to a portion of H. pylori 16s rRNA with the following sequence: 5'-GGA-CATAGGCTGATCTTAGC-3'. ISH using this probe was specific for H. pylori with no cross-reactivity with other bacterial or fungal organisms. Receiver operator characteristic analysis was used to assess the diagnostic performance of ISH and thiazine techniques. ISH and thiazine stains were done on serial sections, reviewed independently, and scored on a graded scale from 1-5 based upon the degree of assurance of H. pylori presence. Diagnostic performance was assessed in 'expert' and 'nonexpert' pathologist groups with the CLOtest serving as the invariant test for relative test comparison. The ISH test performed slightly better (ROC area 0.9) than the thiazine (ROC area 0.8) in the nonexpert population, but equally well in the 'expert' group (ROC area 0.95, 0.95). ISH followed by routine hematoxylin and eosin staining showed detailed mucosal histology with a dramatic visualization of H. pylori along the surface of the foveolar cells with no evidence of lamina propria invasion. In summary, ISH for H. pylori is an excellent test that is specific, easily read, and allows concomitant detailed histologic mucosal examination.