By John Otrompke
CHICAGO -- November 10, 2009 -- Pathogen virulence factors of Helicobacter pylori do not seem to have a role in disease outcomes in African patients, but there seems to be a relationship in host response and disease outcome, according to a study presented here at the American Society for Clinical Pathology (ASCP) 2009 Annual Meeting.
"H pylori is a tiny delicate spiral motile bacterium, which is common in the west but much more prevalent in equatorial regions," said Revathi Gunturu, MD, Department of Pathology and Medicine, Aga Khan University Hospital, Nairobi, Kenya.
"The bacteria is transferred most commonly by the oral-faecal route, but animal sources, water bodies, and environmental contamination are all highly suspected to play a role in transmission as well," said Dr. Gunturu on October 30.
While data on H pylori varies from western literature to literature in the African setting, in Africa, H pylori infection is associated with inflammatory conditions, such as gastritis, peptic ulcer disease, and occasional gastric cancer. "In the past 5 years, we have seen the previous incidence of gastric carcinoma in our hospital doubled," said Dr. Gunturu.
For the study, Dr. Gunturu and colleagues looked for 3 polymorphisms in 290 patients undergoing upper gastrointestinal endoscopy for dyspepsia at Aga Khan University Hospital. They looked for the presence of the cagA gene and variations in the vacA gene, 2 virulence factors in the micro-organism itself, as well as 2 interleukin genes and a tumour necrosis factor-alpha polymorphism in the patients.
In the sample, 52.2% of patients had H pylori. Those infected with peptic ulcer disease were the most commonly infected and in those patients, the rate of infection was 74.2%. The interleukin-1 beta-511 allele T/T was found in 48.4% of peptic ulcer patients, as was interleukin-1RN. Outcomes analysis revealed that 30% of gastritis cases and 10% of peptic ulcer cases were quite severe, Dr. Gunturu added.
On the other hand, the H pylori variant genotypes showed no inclination toward any particular pathology.
"The severity of the gastritis and peptic ulcers we're seeing could be a result of the interplay between the genetics of the Kenyan population and the inflammatory response," said Dr. Gunturu, noting that the secretion of immunologic mediators is known to be different in Africans than in westerners.
Dr. Gunturu said that the researchers are working on a follow-up study to test the hypothesis, involving 86 gastric cancer patients in Germany and 56 patients in Kenya. The study, which looks at interleukin expression and H pylori status, should be done in about 4 months, said Dr. Gunturu.
[Presentation title: Prevalence of Helicobacter pylori Infection, the Virulence Genotypes of the Infecting Strain, and Associated Disease Outcomes in the Kenyan Population. Abstract 42]
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