Food & Nutrition

Arab Journal of Food & Nutrition
76. Development of a Culture Medium for the Isolation of Helicobacter pylori
from Food (2005)
Dina Yassin Akkash\ University of Jordan
Supervisor: Dr. Mohammed Isam Yamani
Helicobacter pylori is a bacterium involved in the pathogenesis of human active
chronic gastritis, peptic and duodenal ulcer diseases and gastric cancer, and its
prevalence is elevated worldwide. It is hypothesized that the transmission of H. pylori
involves multiple pathways: iatrogenic, oral-oral and fecal-oral. Food and water are
suspects of serving as vehicles in the fecal-oral route of H. pylori infection.
The objective of this study was to develop a selective pretreatment of food
samples with urea-HCl mixtures that would facilitate the isolation of H. pylori by
eliminating the food microbial flora. Samples from four types of ready-to-eat food that
are subjected to intensive handling were taken from different restaurants in Amman,
and were seeded with a clinical isolate of H. pylori. Samples were then mixed with
urea-HCl solutions of different strength, incubated for short times at 37°C and cultured
on brain heart infusion agar (BHIA) supplemented with 7% defibrinated sheep blood.
The four samples consisted of hummus (hoummos), vegetable salad, fruit cocktail and
falafel sandwich. Helicobacter pylori was successfully recovered from the inoculated
food samples when pretreated with 0.06N HCl-0.08M urea and 0.12N HCl–0.16M
urea for 5, 10, 15 min. at 37°C. While the pretreatment with 0.18N HCl–0.24M urea
failed to recover the bacterium from the inoculated food samples.
Sixty samples of eight items of selected ready-to-eat foods were tested for the
presence of H. pylori by pretreating the samples with the urea-HCl mixtures and
culturing onto BHIA. These included 10 samples, each of hummus, mutaabl, vegetable
salad and vegetable salad with tahineh, and 5 samples, each of home-made
mayonnaise, fruit cocktail, white cheese sandwiches and shawerma sandwiches.
Samples were also tested for Enterobacteriaceae count as representative of the
contaminating flora of the foods.
Helicobacter pylori was successfully isolated from three samples (5%) out of the
60, namely two samples of hummus and one sample of mutaabl. Enterobacteriaceae
count of the samples ranged from (