Gastric bypass surgery does not increase susceptibility to Helicobacter pylori infection in the stomach of rat or mouse.

Gastric bypass is a clinical option for obesity surgery. An increased susceptibility to Helicobacter pylori infection in the bypassed stomach has been speculated. The aim of the present study was to examine the susceptibility of the bypassed stomach to H. pylori infection in rats and mice. Adult Sprague-Dawley and Wistar rats and NMRI mice were subjected to either gastric bypass or laparotomy only as control. The animals were inoculated with the CagA- and VacA- positive H. pylori strain 67/21 (not mouse-adapted) in the first experiment and with 9 additional isolates in the second, by injection into the bypassed stomach or the control stomach during surgery. The stomach of each animal was collected for H. pylori culture 2-3 weeks later. While all the rats were H. pylori negative, 54% of gastric bypassed mice and 75% of controls were positive (P = 0.4). We conclude that susceptibility to H. pylori infection in the stomach is not increased by gastric bypass surgery.