Occurrence of Helicobacter species other than H. hepaticus in laboratory mice and rats in Sweden.
ABSTRACT The aim of this study was to determine which Helicobacter species other than H. hepaticus colonize laboratory mice and rats in Sweden. We analyzed 63 intestinal samples from mice and 42 intestinal samples from rats by partial 16S rDNA sequence analysis. Previously these samples had been found positive for Helicobacter species but negative for H. hepaticus in a polymerase chain reaction screening assay at the National Veterinary Institute in Sweden. H. ganmani, H. typhlonius, H. rodentium, an uncharacterized Helicobacter species ('hamster B'), and a possibly novel species were detected in mice. The possibly novel species was most closely related to H. apodemus strain YMRC 000216 (98.3% sequence similarity). Two different Helicobacter species were detected in rats: H. ganmani and H. rodentium. H. ganmani colonization of rats has not previously been reported.
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ABSTRACT: Infection of mouse colonies with Helicobacter spp. has become an increasing concern for the research community. Although Helicobacter infection may cause clinical disease, investigators may be unaware that their laboratory mice are infected because the pathology of Helicobacter species is host-dependent and may not be recognized clinically. The effects of Helicobacter infections are not limited to the gastrointestinal system and can affect reproduction, the development of cancers in gastrointestinal organs and remote organs such as the breast, responses to vaccines, and other areas of research. The data we present in this review show clearly that unintentional Helicobacter infection has the potential to significantly interfere with the reliability of research studies based on murine models. Therefore, frequent screening of rodent research colonies for Helicobacter spp. and the eradication of these pathogens should be key goals of the research community.Comparative medicine 03/2009; 59(1):10-7. · 0.76 Impact Factor
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ABSTRACT: Mouse models provide powerful tools to investigate disease mechanisms and are widely used in inflammatory bowel disease research. However, it is common for reports of mouse model studies to lack potentially important information about the microbial status of the mice and the method used to evaluate disease expression for statistical analysis. For example, it is common practice to state that the mice were housed under specific pathogen-free conditions but provide no further information regarding the presence or absence of organisms such as Helicobacter spp. that are known or likely to affect disease expression, thus omitting information potentially important to the expected phenotype of the mice and their responses to experimental manipulation. We therefore encourage authors to use such terms as "conventional" and "specific pathogen-free" precisely, to state the agents from which the mice are represented to be free, and to provide a brief description of the health monitoring protocol. Descriptions of histopathologic methods used to evaluate colitis in mouse models also often do not include sufficient detail to allow readers to understand and evaluate the methods; in addition, the lesions commonly are shown in photomicrographs that are too small and of too low resolution to be interpreted. Inasmuch as such methods are often the major or only source of data upon which conclusions regarding genotype or experimental treatment effects are based, the method employed should be fully described, and photomicrographs should be of adequate size and resolution to allow independent assessment.Inflammatory Bowel Diseases 01/2012; 18(8):1558-65. DOI:10.1002/ibd.22892 · 5.12 Impact Factor
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ABSTRACT: Enterohepatic Helicobacter species (EHS) often are associated with typhlocolitis and rectal prolapse in mice. We sought to describe rectal prolapses histologically, relate lesions to mouse genotype and EHS infection status, and characterize EHS pathogens on our campus. Our mouse population was housed among 6 facilities on our main campus and a seventh, nearby facility. We investigated cases of rectal prolapse over 1 y and included 76 mice, which were broadly categorized according to genotype. Microscopically, lesions ranged from mild to severe typhlocolitis, often with hyperplastic and dysplastic foci. Neoplastic foci tended to occur at the ileocecal-colic junction. Lesions were most severe in strains that had lower-bowel inflammatory disease, notably IL10, Rag1, and Rag2 knockout strains; prolapses occurred in these strains when housed both in areas with endemic EHS and in our Helicobacter-free barrier facility. Most mice with rectal prolapses were immunocompromised genetically modified mice; however, the most frequently sampled strain, the lamellipodin knockout, was noteworthy for its high incidence of rectal prolapse, localized distal colonic and rectal lesions, and lack of known immunodeficiency. This strain is being explored as a model of rectal carcinoma. Most of the colons examined tested PCR-positive for EHS, often with coinfections. Although H. bilis is prevalent on our campus, we did not find this organism in any mice exhibiting clinical signs of rectal prolapse. Identification of H. apodemus in 22% of cases has fueled increased surveillance on our campus to characterize this organism and differentiate it from the closely related H. rodentium.Comparative medicine 01/2014; 64(3):171-178. · 0.76 Impact Factor