Current status of Helicobacter contamination of laboratory mice, rats, gerbils, and house musk shrews in Japan.

The current status of Helicobacter contamination of laboratory mice, rats, gerbils, and house musk shrews from 47, 10, 4, and 3 colonies, respectively, in Japan was studied. Helicobacter was detected by reverse transcription (RT)-nested polymerase chain reaction (PCR) with Helicobacter genus-specific primers by using feces obtained from the animals. H. hepaticus, H. muridarum, H. bilis, H. rodentium, "Flexispira rappini", and "H. suncus" were identified with species-specific primers. Other species of Helicobacter were identified by sequencing of PCR products amplified with genus-specific primers. For mice, H. hepaticus, H. bilis, H. rodentium including H. rodentium-like organism, "H. typhlonicus"-like organism, and H. westmeadii-like organism were detected from 12 (25.5%), 1 (2.1%), 18 (38.3%), 1 (2.1%), and 1 (2.1%) colonies, respectively. Forty-seven (5.7%) mice from six (12.8%) colonies were contaminated with both H. hepaticus and H. rodentium. H. rodentium was detected in rats from three (30.0%) colonies. In gerbils, H. hepaticus was detected in three (75.0%) colonies, but other species of Helicobacter were not detected. In house musk shrews, "H. suncus" was detected in animals from two (66.7%) colonies. Visible lesions in the liver, which showed multiple pale to white foci, were observed in 6/42, 5/174, and 1/21 mice infected with H. hepaticus, H. rodentium, and H. hepaticus/H. rodentium, respectively, and 1/14 gerbils infected with H. hepaticus. The results suggest the prevalence of these species of Helicobacter in mice, rats, gerbils, and house musk shrews in Japan.