Clinical outcome after infection with Helicobacter pylori does not appear to be reliably predicted by the presence of any of the genes of the cag pathogenicity island

Abstract

Background-The development of clinical disease after infection with Helicobacter pylori has been reported to be associated with expression of the cagA gene. Recently, it has been shown that cagA is part of a multigene locus, described as the cag pathogenicity island (PAI). The role of this region in determining clinical outcome remains to be established. Aims-To investigate whether the presence of cagA is always associated with the presence of the complete cag PAI and to evaluate the distribution of selected cag genes in 73 H pylori strains isolated from patients in France. Methods-Clinical strains of H pylori were screened for selected genes of the cag PAI by polymerase chain reaction and colony hybridisation. Results-Of 64 strains that harboured the cagA gene, 57 (89%) also contained the entire cag PAI. The entire cag PAI was found in 85% (48/56) and 53% (9/17) of duodenal ulcer and non-ulcer dyspepsia isolates, respectively. Eight strains had deletions within the cag PAI, including deletion of the cagA gene in one isolate; the deletions were not associated with the insertion sequence IS605. Of eight strains lacking the cag PAI, four were isolated from patients with duodenal ulcer. Conclusion-The cag PAI is not a uniform, conserved entity. Although the presence of the cag PAI is highly associated with duodenal ulcer, the clinical outcome of infection with H pylori is not reliably predicted by any gene of the cag PAI. (Gut 1998;43:752-758)

Distribution ofcagGgene inHelicobacter pyloriisolates from Chinese patients with different gastroduodenal diseases and its clinical and pathological significance

“…Nevertheless, our study suggested that positive rate of cagG in H pylori was high and cagG was quite conservative in Chinese population, and that there was no difference in the frequencies of cagG-positive isolates among patients with gastritis, duodenal ulcer, gastric ulcer or gastric duodenal ulcer. Our results are supported by the study by Jenks et al [20] who demonstrated that no specific genes within the cag PAI could reliably predict the clinical outcome of H pylori infection in French patients, and also by Hsu et al [17] who concluded that any of the cag PAI genes such as cagE could not predict the clinical presentation in Korean patients.…”

Functional Cytotoxin Associated Gene A in Helicobacter pylori Strains and Its Association with Integrity of Cag-pathogenicity Island and Histopathological Changes of Gastric Tissue

“…Ahmadzadeh et al represented 13 different cagPAI genotyptes among 21 cagPAI positive H. pylori strains in Iran (34).This diversity is also high in different geographic populations (11,(35)(36)(37). Correlation between integrity of cagPAI, types of EPIYA motifs, and disease outcome was confirmed by several studies (24,(38)(39)(40)(41)(42). However, there are studies that reported contrary results (43)(44)(45).…”

Association of cag E Gene and LL-37 Serum Level with Helicobacter pylori-induced Peptic Ulceration in Egyptian Patients

“…In addition, Day et al [36] detected that 12 out of 13 children (92%) with duodenal ulcers were infected with Cag E-positive isolates, compared with only 5 out of 16 (31%) with gastritis alone. Although French study found that 51 out of 56 (91%) strains isolated from patients with duodenal ulcers were Cag E-positive, whereas 13 out of 17 (76%) H. pylori isolates obtained from patients with gastritis alone were positive but with non statistically significant difference between duodenal ulcer and gastritis patents [37]. This difference was explained as different geographic location of the patients may affect the results of the studies.…”