Identification of markers for the major pathogenicity factors of Helicobacter pylori

BACKGROUND: Identification of Helicobacter pylori pathogenicity factors is crucial for improving diagnosis and understanding the pathogenesis of associated diseases.

AIM: The study aimed to establish the detection rates of markers associated with major H. pylori pathogenic factors in patients with chronic gastritis and peptic ulcer.

METHODS: The study included 67 patients with chronic gastritis and 57 patients with peptic ulcer. All participants underwent a fibroesophagogastroduodenoscopy with a rapid urease test (AMA LLC, Russia), followed by a histological examination for H. pylori. The following were also tested: stool filtrates for H. pylori antigen using an immunochromatographic assay (H. pylori test, Novamed Ltd., Israel); serum for anti-CagA antibodies via enzyme-linked immunosorbent assay (Anti-Helicobacter pylori CagA ELISA, ECOlab JSC, Russia); and fecal and salivary samples for O antigen (LPS), VacA, and CagA antigens using a coagglutination test (Gamaleya National Research Center for Epidemiology and Microbiology, Russia).

RESULTS: Positive rapid urease test results were obtained in 61.9% of patients. Serum CagA antibodies were detected in 51% of patients, and H. pylori antigen was detected in the feces of 27.9% of patients (p ≥ 0.05). The coagglutination test demonstrated the highest diagnostic performance: O antigen, VacA, and CagA antigens were detected in the fecal and/or salivary samples of 83.1% of patients at a diagnostic titer threshold of ≥1:8, which was significantly higher than that achieved by other tests. The rate of CagA antibody detection in serum was twice as high with a positive rapid urease test result. Esophagogastroduodenoscopy and rapid urease testing revealed H. pylori in 40.3% (27) of patients with chronic gastritis and in 56.1% (31) of patients with peptic ulcers. The coagglutination test detected VacA and/or CagA antigens in 90.6% of stool filtrate samples and 88.5% of salivary samples. Both antigens simultaneously were detected in 67.5% and 65.1% of the fecal and salivary samples, respectively. The rate of simultaneous detection of VacA and CagA antigens in feces was significantly higher in patients with peptic ulcers and positive rapid urease test results compared with other subgroups. There was no significant difference in the rate of simultaneous detection of these antigens in saliva across patient subgroups.

CONCLUSION: The primary advantage of the coagglutination test is the non-invasive, simultaneous detection of three key, synergistic H. pylori pathogenicicty factors in feces and/or saliva: O antigen (a marker of replication), VacA antigen (vacuolating cytotoxin), and CagA antigen (a pathogenicity island marker and Class I bacterial co-oncogene) The study confirmed that saliva can be used to detect H. pylori in children and older patients, when invasive testing is not an option.