Abstract
Helicobacter pylori infections and gastroduodenal diseases have been reported several times in this region but there is no data
regarding prevalence of H. pylori VacA and CagA genotypes in this part of the world. The objective of this study was to determine the
prevalence of H. pylori genotypes in different gastroduodenal disease patients of Karachi.
Multiple biopsy samples were taken from 227 patients of peptic ulcer disease (PUD), chronic gastritis (CG) and/or abdominal
discomfort (AD) in the gastroenterology departments from three different health institutions of Karachi and processed for rapid urease
test, culture and histopathology. Positive isolates were further confirmed by PCR amplification of the phosphoglucosamine mutase
gene (glmM) and analyzed for the occurrence of CagA and VacA genotypes by PCR.
A significant association between H. pylori infection and gastroduodenal diseases was observed (p<0.001). Out of 227 biopsy samples
120 (52.8%) were confirmed positive for H. pylori in which 56 were that of PUD, 37 with CG, 19 with AD and 8 with gastric cancer
(GCa). Overall 92% isolates from patients with PUD, CG, AD and GCa were CagA positive. Eighty five (70.8 %) of 120 strains had
VacA signal sequence genotype s1a, 19 (16%) had type s1b and 16 (13%) had type s2. The VacA middle region type m1 and m2 were
detected in 78(65%) and 42 (35%) strains. The combinations s1a/m1 and s1a/m2 were found in 66(55%) and 19 (15.8%) respectively.
The s1b/m1 and s1b/m2 were found in 12(10%) and 8(6.6%) strains respectively. The s2m2 combinations were identified in
15(12.5%) of 120 isolates. The s2m1 combination was not found in any strain. Forty eight (85.7%) of 56 patients with PUD, 25
(67.5%) of 37 patients with CG, 5 (26.3%) of 19 patients with AD and 7 (87.5%) of 8 with GCa harbored type s1a strains. Genotypes
s1a/m1 with positive CagA are commonly associated with PUD, CG, AD and GCa.
