Adaptation of the [13C]urea breath test as a noninvasive method for detection of Helicobacter pylori infection in squirrel monkeys (Saimiri spp.).

The [13C]urea breath test was adapted for use in squirrel monkeys (Saimiri spp.) for identification of experimentally induced infection with Helicobacter pylori, the bacterium causing gastric ulcer in humans. A canine anesthesia inhalation mask was modified with a volume-reducing insert allowing sufficient breath collection from these small primates within 30 sec. Fourteen milligrams of [13C urea per kilogram of body weight was adequate for clear distinction between experimentally infected and noninfected animals. Initial infection of five squirrel monkeys resulted in increased 13CO2 in breath within 3 days after inoculation with H. pylori. Additional inoculation with H. pylori superimposed on an existing gastric population caused a transient increase in breath 13CO2 values, which gradually declined over the following 15 days. Breath test results indicating H. pylori infection were confirmed by high [13C] concentration in blood, by urease-positive culture, modified Steiner stain reaction, and Western blot analysis. This modified [13C]urea breath test provides a rapid, reproducible, noninvasive method for screening small primates used as nonhuman models for the study of gastric infection with H. pylori.