Resistance of Sprague-Dawley Rats to infection with Helicobacter pullorum.

Helicobacter pullorum is an enterohepatic Helicobacter spp. known to infect both chickens and humans. H. pullorum infection has recently been reported in both mice and rats. This study was designed to determine whether standard methods of colony health surveillance using exposure to rodent soiled bedding could detect H. pullorum in Sprague-Dawley rats. We exposed 8 Helicobacter-free Sprague-Dawley rats to bedding from H. pullorum-infected Brown Norway rats. Fecal samples were analyzed by PCR every 2 wk for 22 wk. Dirty bedding transfer resulted in intermittent positive fecal PCR results; however, none of the rats became persistently infected with H. pullorum. Select intestinal tissues collected at necropsy analyzed by PCR were negative for H. pullorum. To determine whether the failure to detect H. pullorum in Sprague-Dawley rats receiving contact bedding was due to resistance of Sprague-Dawley rats to H. pullorum colonization, 10 Helicobacter-free Sprague-Dawley rats were orally dosed with H. pullorum. Fecal samples were analyzed by PCR every 2 wk for 12 wk. At 2 wk after infection, 5 of 10 rats were PCR positive for H. pullorum. By 12 wpi, only 2 rats were persistently colonized with H. pullorum according to culture and PCR results. These data contrast with our previous data, which showed a high frequency of both natural and experimental H. pullorum infection in Brown Norway rats. Sprague-Dawley rats are resistant to experimentally induced H. pullorum gastrointestinal colonization when dosed orally with H. pullorum or exposed to bedding from H. pullorum-infected rats.