Pathology, diagnosis and epidemiology of the rodent Helicobacter infection

Since the first isolation of Helicobacter pylori from humans in 1983, 18 Helicobacter species have been identified during the last decade in domestic and laboratory animals. Several Helicobacter species have been isolated from the gastrointestinal tracts of various mammalian species and birds. Helicobacter hepaticus, H. muridarum, H. bilis, H. rodentium and Flexispira rappini have been isolated from mice. Among these species, only H. hepaticos has been clearly recognized as a pathogen. Indeed, it displays the pathogenic potential to elicit hepatitis in several strains of mice; moreover in A/JCr mice, it is strongly associated with hepatic cancer. Among the five murine helicobacter species, apart from H. hepaticus, F. rappini has not been found associated with lesions, H. muridarum has been observed in gastric glands of mice with chronic gastritis, and H. bilis has been reported in the liver of mice with chronic hepatitis. When associated with H. rodentium, H. bilis is able to induce diarrhea in SCID mice. In no case has pathogenicity of a single species been clearly proven. In rats, H. trogontum and H. muridarum have been isolated from the intestine, without any information concerning their respective pathogenicity. H. cinaedi and H. cholecystus have been identified from the intestine and the gallbladders of hamsters, respectively. The diagnosis of Helicobacter species by polymerase chain reaction (PCR) is a rapid, specific and sensitive technique. One of the most promising diagnostic techniques of these infections seems to be the PCR detection of Helicobacter sp. from feces based on the 16S rRNA sequences, then a restriction enzyme analysis to identify the actual species. Several drug regimens have also been evaluated to eradicate H. hepaticus from mice. Helicobacter infections, particularly H. hepaticus and H. bilis, seem to be widespread in laboratory mouse colonies and have also been detected from commercial breeders.