Impact of Helicobacter pylori virulence markers on clinical outcomes in adult populations

Abstract

Background: In recent years, associations between specific virulence markers of Helicobacter pylori (H. pylori) and gastrointestinal disorders have been suggested.

Aim: To investigate the presence of virulence factors including vacuolating cytotoxin A genotypes (s1m1, s1m2, s2m1, and s2m2), cytotoxin-associated gene A (CagA), and urease activity in H. pylori strains isolated from Arab and Jewish populations in northern Israel and to assess associations between these factors and patients' demographics and clinical outcomes.

Methods: Patients (n = 108) who underwent gastroscopy at the Baruch Padeh Medical Center, Poriya due to symptomatic gastroduodenal pathologies as part of H. pylori diagnosis were enrolled in the study. Gastric biopsy specimens were collected from the antrum of the stomach. Clinical condition was assessed by clinical pathology tests. Bacteria were isolated on modified BD Helicobacter Agar (BD Diagnostics, Sparks, MD, United States). Bacterial DNA was extracted, and PCR was performed to detect CagA and vacuolating cytotoxin A genes. Urease activity was assessed using a rapid urease test.

Results: A significant correlation was found between disease severity and patient ethnicity (P = 0.002). A significant correlation was found between CagA presence and the s1m1 genotype (P = 0.02), which is considered the most virulent genotype. Further, a higher level of urease activity was associated with isolates originating from the Jewish population. Moreover, higher urease activity levels were measured among CagA-/s1m1 and CagA-/s2m2 isolates.

Conclusion: Our study highlights the importance of incorporating molecular methods for detection of virulence markers of H. pylori in order to tailor optimal treatments for each patient. Further investigation should be performed regarding associations between H. pylori virulence factors and ethnicity.

Keywords: Cytotoxin-associated gene A; Helicobacter pylori; Urease activity; Vacuolating cytotoxin A; Virulence factors.

Figure 1

Distribution of the different vacuolating cytotoxin A genotypes (percentage) among 108 isolates, according to cytotoxin-associated gene A presence. VacA: Vacuolating cytotoxin A; CagA: Cytotoxin-associated gene A. ^aP < 0.05.

Figure 2

Urease activity in relation to ethnicity, sex, cytotoxin-associated gene occurrence, and place of residence. A: Ethnicity; B: Sex; C: Cytotoxin-associated A gene occurrence; D: Place of residence. Urease activity (indicated by O.D) was measured 1 min after incubation of bacteria with urea solution, as described in the Materials and Methods section. VacA: Vacuolating cytotoxin A; CagA: Cytotoxin-associated gene A.

Figure 3

Urease activity as a function of isolate genotype combination. Urease activity was measured 1 min, 5 min, and 10 min after incubation of bacteria with urea solution, as described in the Materials and Methods section. The minimal, maximal, and median of mean urease activity values are shown (the median is indicated by the line within the bar) per each group of isolates with a different genotype of cytotoxin-associated gene A and vacuolating cytotoxin A genes. O.D: Optical density; VacA: Vacuolating cytotoxin A; CagA: Cytotoxin-associated gene A. ^aP < 0.05.