Background
The establishment of Helicobacter pylori in the stomach and duodenum is associated with gastritis, peptic ulcers, and gastric cancer. Application of suitable methods, including molecular techniques, for an accurate detection of H. pylori can lead to the administration of appropriate drugs and successful therapy. In this study, fluorescent in situ hybridization (FISH) was compared with histology for the diagnosis of H. pylori in gastric biopsy specimens.
Material and Method
Flourescently labeled oligonucleotdie probes that target ribosomal RNA were utilized in the FISH procedure. Ninety-one gastric biopsy specimens were tested by FISH and by histology using hematoxylin-eosin (H-E) and Geimsa stains. Furthermore, clarithromycin resistance in 39 of the 91 specimens was examined by FISH.
Results
The sensitivity and specificity of FISH for the detection of H. pylori were 97.9% and 100%, respectively. Of the 39 samples that were tested for clarithromycin resistance, 19 were FISH positive for H. pylori, of which 15 and 4 specimens were infected with clarithromycin-susceptible and clarithromycin-resistant strains, respectively. There were coccoid forms of H. pylori in a few of the specimens.
Conclusions
FISH is a highly sensitive and specific technique for the diagnosis of H. pylori infection. It can be a method of identification when a patient is infected with coccoid forms of H. pylori. The ability of FISH for determination of clarithromycin resistance is a considerable advantage of this method over histology.

Keywords: In Situ Hybridization, Fluorescence - utilization, Histocytochemistry - methods, Helicobacter pylori - metabolism, Helicobacter Infections - drug therapy, Gastric Mucosa - pathology, Drug Resistance, Bacterial, Sensitivity and Specificity, Clarithromycin - therapeutic use, Biopsy, Anti-Bacterial Agents - therapeutic use