Helicobacter canis isolated from a dog liver with multifocal necrotizing hepatitis

Helicobacter turcicus sp. nov., a catalase-negative new member of the Helicobacter genus, isolated from Anatolian Ground Squirrel (Spermophilus xanthoprymnus) in Turkey

Eleven Gram-negative, curved and S-shaped, oxidase activity positive, catalase activity negative bacterial isolates recovered from faeces of Anatolian ground squirrel (Spermophilus xanthoprymnus) in the city of Kayseri, Turkey, were subjected to a polyphasic taxonomic study. Results of a genus-specific PCR revealed that these isolates belonged to the genus Helicobacter . The 16S rRNA gene sequence analysis revealed that the 11 isolates had over 99 % sequence identity with each other and were most closely related to Helicobacter ganmani CMRI H02T with 97.0–97.1 % identity levels and they formed a novel phylogenetic line within the genus Helicobacter . Faydin-H64 and Faydin-H70T strains were subjected to gyrA and atpA gene and whole genome sequence analyses. These two Helicobacter strains formed separate phylogenetic clades, divergent from other known Helicobacter species. The DNA G+C content and genome size of the strain Faydin-H70T were 35.3 mol% and 1.7 Mb, respectively. Average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between strain Faydin-H70T and its close phylogenetic neighbour H. winghamensis ATCC BAA-430T were determined as 81.7 and 34.9 %, respectively. Pairwise sequence comparison showed that it was closely related to H. ganmani CMRI H02T however it shared the highest ANI and dDDH values with H. winghamensis ATCC BAA-430T. The data obtained from the polyphasic taxonomy approach, including phenotypic characterization and whole-genome sequences, revealed that these strains represent a novel species within the genus Helicobacter , for which the name Helicobacter turcicus sp. nov., is proposed with Faydin-H70T as the type strain (=DSM 112556T=LMG 32335T).

Helicobacter canis: A Review of Microbiological and Clinical Features

Helicobacter canis, an enterohepatic Helicobacter, has proven its role in human diseases and has been rediscussed in recent years as its zoonotic potential is increasingly described. Routine microbiological detection of this pathogen is a difficult task as its culture may fail due to fastidious growth. It is therefore supposed that many clinical laboratories under-recognize H. canis infections. A review of all clinical and microbiological literature currently available from previous relevant H. canis human clinical cases, mainly bacteremia, added with a clinical case observed at the Cliniques universitaires Saint-Luc, was performed. Clinical features of H. canis reports show the presence of underlying clinical conditions in 89% of the cases, bacteremia in 83%, associated fever in 58%, and recent close contact with pets in 83%, especially dogs. The observed microbiological trends from 10 cases of bacteremia were a median of 4 days until positive blood culture bottle detection, subcultures showing a thin layer of small colonies under microaerophilic atmosphere at 35–42°C after 3–4 days of growth, and an identification requiring 16S rRNA sequencing given the difficulties observed with MALDI-TOF MS. Low MICs were observed for penicillins, amoxicillin/clavulanic acid, carbapenems, and metronidazole in opposition to high MICs for ciprofloxacin. A frequent association of H. canis and bacteremia in immunocompromised patients with recurrent fever in contact with pets, especially dogs, was identified. Considering the fastidious growing capacities, final identification from blood cultures may not be expected before 7 days. Intravenous ceftriaxone, oral doxycycline, or metronidazole has been suggested as efficient therapeutic choices.

Pet-related bacterial zoonotic infections: Three cases of severe infections in the immunocompromised host

Pets can have many positive effects on their owners. However, close contact with pets offers optimal conditions for transmission of micro-organisms. Especially immunocompromised patients are at risk for zoonotic infections. Here we describe the diagnosis, microbiology and treatment of three patients with severe zoonotic infections with Helicobacter canis, Pasteurella multocida and Capnocytophaga canimorsus. With this case report we would like to emphasize the importance of awareness for pet-related zoonotic infections in immunocompromised patients.

Helicobacters and cancer, not only gastric cancer?

The Helicobacter genus actually comprises 46 validly published species divided into two main clades: gastric and enterohepatic Helicobacters. These bacteria colonize alternative sites of the digestive system in animals and humans, and contribute to inflammation and cancers. In humans, Helicobacter infection is mainly related to H. pylori, a gastric pathogen infecting more than half of the world's population, leading to chronic inflammation of the gastric mucosa that can evolve into two types of gastric cancers: gastric adenocarcinomas and gastric MALT lymphoma. In addition, H. pylori but also non-H. pylori Helicobacter infection has been associated with many extra-gastric malignancies. This review focuses on H. pylori and its role in gastric cancers and extra-gastric diseases, as well as malignancies induced by non-H. pylori Helicobacters. Their different virulence factors and their involvement in carcinogenesis is discussed. This review highlights the importance of both gastric and enterohepatic Helicobacters in gastrointestinal and liver cancers.

Cytolethal distending toxin: from genotoxin to a potential biomarker and anti-tumor target

Cytolethal Distending Toxin (CDT) belongs to the AB toxin family and is produced by a plethora of Gram-negative bacteria. Eight human-affecting enteropathogens harbor CDT that causes irritable bowel syndrome (IBS), dysentery, chancroid, and periodontitis worldwide. They have a novel molecular mode of action as they interfere in the eukaryotic cell-cycle progression leading to G₂/M arrest and apoptosis. CDT, the first bacterial genotoxin described, is encoded in a single operon possessing three proteins, CdtA, CdtB, and CdtC. CdtA and CdtC are needed for the binding of the CDT toxin complex to the cholesterol-rich lipid domains of the host cell while the CdtB is the active moiety. Sequence and 3D structural-based analysis of CdtB showed similarities with nucleases and phosphatases, it was hypothesized that CdtB exercises a biochemical function identical to both these enzymes. CDT is secreted through the outer membrane vesicles from the producing bacteria. It is internalized in the target cells via clathrin-dependent endocytosis and translocated to the host cell nucleus through the Golgi complex and ER. This study discusses the virulence role of CDT, causing pathogenicity by acting as a tri-perditious complex in the CDT-producing species with an emphasis on its potential role as a biomarker and an anti-tumor agent.

Enterohepatic Helicobacter species - clinical importance, host range, and zoonotic potential

The genus Helicobacter defined just over 30 years ago, is a highly diverse and fast-growing group of bacteria that are able to persistently colonize a wide range of animals. The members of this genus are subdivided into two groups with different ecological niches, associated pathologies, and phylogenetic relationships: the gastric Helicobacter (GH) and the enterohepatic Helicobacter (EHH) species. Although GH have been mostly studied, EHH species have become increasingly important as emerging human pathogens and potential zoonotic agents in the last years. This group of bacteria has been associated with the development of several diseases in humans from acute pathologies like gastroenteritis to chronic pathologies that include inflammatory bowel disease, and liver and gallbladder diseases. However, their reservoirs, as well as their routes of transmission, have not been well established yet. Therefore, this review summarizes the current knowledge of taxonomy, epidemiology, and clinical role of the EHH group.

Exploring the role of healthy dogs as hosts of enterohepatic Helicobacter species using cultivation-dependent and -independent approaches

Enterohepatic Helicobacter (EHH) species have been increasingly associated with acute gastroenteritis, inflammatory bowel disease and hepatobiliary diseases in humans. However, their host range and transmission routes are poorly understood. Therefore, the aim of this study was to determine the presence of EHH in healthy dogs using both cultivation-dependent and -independent methods. Three hundred and ninety faecal samples from domestic dogs without gastrointestinal symptoms were analysed between June 2018 and July 2019 in Valdivia (South of Chile). Samples were inoculated on selective medium and in parallel were filtrated over an antibiotic-free blood agar. Both media were incubated in a microaerobic atmosphere at 37°C for 7 days. Colonies were identified by PCR and phylogenetic analysis. A subset of 50 samples (half of them positive for EHH by cultivation and the remaining half negative) was analysed by PCR-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) for direct detection. Cultivation method detected EHH in 15.4% (60/390) of the samples, being the most prevalent species H. canis (5.8%, 23/390) and H. canicola (5.1%, 20/390), followed by H. bilis (3.6%, 14/390) and 'H. winghamensis' (1.3%, 5/390). In contrast, PCR-DGGE method detected Helicobacter DNA in almost all (96%, 48/50) tested samples. On the other hand, the method used also allowed to isolate other Campylobacterales, in fact 44.3% (173/390) of the samples were positive for Campylobacter upsaliensis (43.3%, 169/390) followed by C. jejuni (2.0%, 8/390). Moreover, two strains that presented Campylobacter-like morphology were finally identified as Anaerobiospirillum succiniciproducens. Our results indicate that healthy domestic dogs commonly carry EHH and other Campylobacter species. However, further studies are needed to determine whether and how these Helicobacter and Campylobacter species can be transmitted to humans.

Helicobacter infection in the hepatobiliary system and hepatic lesions: a possible association in dogs

Helicobacter infection has been associated with hepatobiliary diseases in humans and animals. The aims of this study were to identify Helicobacter species in the hepatobiliary tract of dogs and to elucidate the possible association of these bacteria in liver diseases. Twenty-seven gastric and hepatobiliary samples were collected from 33 dogs with hepatic lesions and 17 dogs with no liver histological changes. Warthin-Starry staining, immunohistochemical assay, and PCR were performed to detect the presence of Helicobacter. Helicobacter genus was detected in 21.2% of the samples with hepatic lesions. The main lesion was chronic hepatitis. Immunohistochemistry revealed infection in liver (1/5) and gallbladder (1/3) 32 samples. The sequence analysis of seven amplicons of the 16S rRNA gene of Helicobacter genus from hepatobiliary samples showed 97.8 to 100% of nucleotide identity with gastric helicobacter. One amplicon of the ureA and ureB gene of Helicobacter genus from the stomach showed 89.1 to 90.7% nucleotide identity with H. heilmannii. The presence of Helicobacter genus in liver samples showing hepatic lesions suggests the involvement of these bacteria in the etiology of hepatobiliary disease in dogs. DNA sequences were similar to gastric Helicobacter species, reinforcing the hypothesis of bacterial translocation from the stomach to liver by the biliary pathway.

Hepatic leptospiral infections in dogs without obvious renal involvement

Background

Reports of chronic hepatitis in dogs caused by Leptospira spp. are confined to small case series. Fluorescence in situ hybridization (FISH) allows the identification of spirochetes in liver samples. Consequently, this technique may help elucidate the role of Leptospira spp. in cases of chronic hepatitis.

Objectives

To describe cases of hepatic leptospirosis in dogs diagnosed by FISH and subsequent polymerase chain reaction (PCR) speciation, with the absence of clinically relevant renal involvement.

Animals

Ten client‐owned dogs.

Methods

Retrospective case series from the University of Cambridge presented between 2013 and 2016 or cases consulted by telephone advice during this time period. Cases were selected based on histopathologically confirmed granulomatous hepatitis and leptospiral organisms identified by FISH and PCR speciation (Leptospira interrogans/kirschneri).

Results

All cases had increased liver enzyme activities, and FISH in combination with PCR speciation‐confirmed infection with L. interrogans/kirschneri. Four dogs underwent repeat liver biopsy, FISH and PCR speciation 4‐15 months after initial presentation and doxycycline treatment with 1 dog undergoing repeat sampling at necropsy. Three dogs that underwent repeat biopsy remained positive for L. interrogans/kirschneri infection. Six dogs were alive at the time of manuscript preparation and 4 dogs were euthanized as a result of progressive liver disease.

Conclusions and Clinical Importance

The presence of hepatic leptospiral organisms may be associated with chronic granulomatous hepatitis without clinical evidence of renal involvement. Further studies are necessary to elucidate the etiological role of these organisms in the disease.

Canine Hepatitis Associated with Intrahepatic Bacteria in Three Dogs

This case report describes the detection of intrahepatic bacteria in formalin-fixed paraffin-embedded histopathological sections from three dogs with neutrophilic, pyogranulomatous, or lymphoplasmacytic hepatitis and cholangiohepatitis. In each of these cases, eubacterial fluorescence in situ hybridization enabled colocalization of intrahepatic bacteria with neutrophilic and granulomatous inflammation in samples that were negative for bacteria when evaluated by routine hematoxylin and eosin histopathology augmented with histochemical stains. Positive responses to antimicrobial therapy were observed in of 2 out of 2 patients that were treated with antimicrobials. These findings suggest that eubacterial fluorescence in situ hybridization analysis of formalin-fixed paraffin-embedded histopathological sections is more sensitive than conventional histochemical stains for the diagnosis of bacteria-associated canine hepatitis.

The Cytolethal Distending Toxin Contributes to Microbial Virulence and Disease Pathogenesis by Acting As a Tri-Perditious Toxin

This review summarizes the current status and recent advances in our understanding of the role that the cytolethal distending toxin (Cdt) plays as a virulence factor in promoting disease by toxin-producing pathogens. A major focus of this review is on the relationship between structure and function of the individual subunits that comprise the AB₂ Cdt holotoxin. In particular, we concentrate on the molecular mechanisms that characterize this toxin and which account for the ability of Cdt to intoxicate multiple cell types by utilizing a ubiquitous binding partner on the cell membrane. Furthermore, we propose a paradigm shift for the molecular mode of action by which the active Cdt subunit, CdtB, is able to block a key signaling cascade and thereby lead to outcomes based upon programming and the role of the phosphatidylinositol 3-kinase (PI-3K) in a variety of cells. Based upon the collective Cdt literature, we now propose that Cdt is a unique and potent virulence factor capable of acting as a tri-perditious toxin that impairs host defenses by: (1) disrupting epithelial barriers; (2) suppressing acquired immunity; (3) promoting pro-inflammatory responses. Thus, Cdt plays a key role in facilitating the early stages of infection and the later stages of disease progression by contributing to persistence and impairing host elimination.

Hepatic Temporal Gene Expression Profiling in Helicobacter hepaticus-Infected A/JCr Mice

Helicobacter hepaticus infection of A/JCr mice is a model of infectious liver cancer. We monitored hepatic global gene expression profiles in H. hepaticus infected and control male A/JCr mice at 3 months, 6 months, and 1 year of age using an Affymetrix-based oligonucleotide microarray platform on the premise that a specific genetic expression signature at isolated time points would be indicative of disease status. Model based expression index comparisons generated by dChip yielded consistent profiles of differential gene expression for H. hepaticus infected male mice with progressive liver disease versus uninfected control mice within each age group. Linear discriminant analysis and principal component analysis allowed segregation of mice based on combined age and lesion status, or age alone. Up-regulation of putative tumor markers correlated with advancing hepatocellular dysplasia. Transcriptionally down-regulated genes in mice with liver lesions included those related to peroxisome proliferator, fatty acid, and steroid metabolism pathways. In conclusion, transcriptional profiling of hepatic genes documented gene expression signatures in the livers of H. hepaticus infected male A/JCr mice with chronic progressive hepatitis and preneoplastic liver lesions, complemented the histopathological diagnosis, and suggested molecular targets for the monitoring and intervention of disease progression prior to the onset of hepatocellular neoplasia.

Draft genome sequences of eight enterohepatic helicobacter species isolated from both laboratory and wild rodents

The draft genome sequences of eight enterohepatic Helicobacter species, H. muridarum, H. trogontum, H. typhlonius, and five unnamed helicobacters, are presented here. Using laboratory mice pervasively infected with helicobacters, we characterized the presence of known virulence factors.

Draft genome sequences of six enterohepatic helicobacter species isolated from humans and one from rhesus macaques

Draft genome sequences of seven enterohepatic Helicobacter species, H. bilis, H. canadensis, H. canis, H. cinaedi, H. winghamensis, H. pullorum, and H. macacae, are presented. These isolates were obtained from clinical patients and a nonhuman primate. Due to potential zoonotic risks, we characterized antibiotic resistance markers and Helicobacter virulence factors.

Evaluation of Gastric Lesions Based on Helicobacter pylori and Helicobacter-Like Organisms (HLOs) in Cats; A Histopathological and Bacteriological Study

Background:

The lesions induced by Helicobacter pylori in a candidate animal model should always be examined thoroughly. The resemblance of these lesions to those observed in humans can indicate whether the usage of this model will contribute to the understanding of the various pathogenic mechanisms involved in the development of human H. pylori-associated diseases.

Objectives:

The aim of this study was to perform a histopathological and bacteriological evaluation of gastric lesions based on H. pylori and Helicobacter-like organisms (HLOs) in cats.

Materials and Methods:

The present study was carried out on 28 cat’s (13 male and 15 female cases) gastric mucosae, which were tested by bacteriological and histopathological methods. Biochemical tests such as catalase, oxidase and urease were utilized in addition to Gram and Giemsa staining.

Results:

This research demonstrated that solely one case of H. pylori was isolated by gastric mucosal culture. Microscopically, the infected stomachs by HLOs comprised a mild to severe diffuse lymphoplasmacytic infiltration into the subglandular and gastric mucosa. Lymphoid follicles were also marked, particularly within pyloric tissues and mostly in displaced mucosal glands. For 75% of the gastritis cases, both HLOs and rapid urease tests were positive, whereas 83% of cases were more than one-year-old with gastritis. Furthermore, 75% of cats indicated gastritis, though 25% encompassed no gastritis; hence 20% had negative results for the rapid urease test and 25% for the Giemsa staining test. Such results may indicate that cats without gastritis were considered as free of HLOs pathogenic bacteria.

Conclusions:

These results suggest that most cases of gastritis were located in the antral region. Additionally, the isolation of H. pylori from domestic cats raises the possibility of zoonotic characteristics for the slightly pathogen; therefore transmission occurs from cats to human and vice versa.

Helicobacter canis colonization in sheep: a Zoonotic link

BACKGROUND

Helicobacter canis has been associated with hepatobiliary and gastrointestinal disease in dogs, cats, and humans. Infection has not been documented in other species.

MATERIALS AND METHODS

Sheep feces subjected to microaerobic culture. Isolates were characterized by genus-specific PCR, restriction fragment length polymorphism, biochemical profiling, and 16S rRNA sequence analysis.

RESULTS

Helicobacter canis was isolated from sheep feces and confirmed by the above methods. These isolates are distinct from other sheep-origin enterohepatic Helicobacter species previously isolated.

CONCLUSIONS

This study identifies sheep as H. canis reservoirs potentially important in zoonotic or foodborne transmission.

Chronic hepatitis in the English springer spaniel: clinical presentation, histological description and outcome

Medical records and liver histology of 68 English springer spaniels (ESS) with a histological diagnosis of CH were reviewed retrospectively. PCR was performed on liver tissue for canine adenovirus-1 (CAV-1), canine parvovirus, canine herpesvirus and pathogenic Leptospira species. Follow-up information was obtained to calculate survival times. Median age at presentation was three years seven months (range, seven months to eight years five months) and there were 48 female and 20 male dogs. Clinical signs were non-specific and five dogs were asymptomatic. All dogs had an increase in serum activity of one or more hepatobiliary enzymes. Histopathology demonstrated hepatocyte necrosis and apoptosis with varying amounts of fibrosis. A predominantly lymphoplasmacytic infiltrate throughout the hepatic parenchyma was found in all 68 dogs, but 45 of these dogs also had a neutrophilic component to the inflammatory infiltrate. There was no significant copper accumulation and no aetiological agent was identified by PCR. The median survival time was 189 days (range, 1 to 1211 days), 38 dogs died within three months and 12 dogs survived more than a year following diagnosis.

Cytolethal distending toxin: a conserved bacterial genotoxin that blocks cell cycle progression, leading to apoptosis of a broad range of mammalian cell lineages

Cytolethal distending toxin (CDT) is a heterotrimeric AB-type genotoxin produced by several clinically important Gram-negative mucocutaneous bacterial pathogens. Irrespective of the bacterial species of origin, CDT causes characteristic and irreversible cell cycle arrest and apoptosis in a broad range of cultured mammalian cell lineages. The active subunit CdtB has structural homology with the phosphodiesterase family of enzymes including mammalian DNase I, and alone is necessary and sufficient to account for cellular toxicity. Indeed, mammalian cells treated with CDT initiate a DNA damage response similar to that elicited by ionizing radiation-induced DNA double strand breaks resulting in cell cycle arrest and apoptosis. The mechanism of CDT-induced apoptosis remains incompletely understood, but appears to involve both p53-dependent and -independent pathways. While epithelial, endothelial and fibroblast cell lines respond to CDT by undergoing arrest of cell cycle progression resulting in nuclear and cytoplasmic distension that precedes apoptotic cell death, cells of haematopoietic origin display rapid apoptosis following a brief period of cell cycle arrest. In this review, the ecology of pathogens producing CDT, the molecular biology of bacterial CDT and the molecular mechanisms of CDT-induced cytotoxicity are critically appraised. Understanding the contribution of a broadly conserved bacterial genotoxin that blocks progression of the mammalian cell cycle, ultimately causing cell death, should assist with elucidating disease mechanisms for these important pathogens.

Experimental Helicobacter marmotae infection in A/J mice causes enterohepatic disease

Helicobacter marmotae has been identified in the inflamed livers of Eastern woodchucks (Marmota monax) infected with woodchuck hepatitis virus (WHV), as well as from the livers of WHV-negative woodchucks. Because the majority of WHV-positive woodchucks with hepatic tumours were culture or PCR positive for this helicobacter, and WHV-negative woodchucks with H. marmotae had hepatitis, the bacterium may have a role in tumour promotion related to chronic inflammation. In this study, the type strain of H. marmotae was inoculated intraperitoneally into 48 male and female A/J mice, a strain noted to be susceptible to Helicobacter hepaticus-induced liver tumours. Sixteen mice served as mock-dosed controls. At 6, 12 and 18 months post-inoculation (p.i.), there were statistically significant (P<0.05) differences in mean inflammation scores for the caecum and proximal colon between experimentally infected and control mice. Differences in hepatic inflammation were significant (P<0.05) at 6 and 12 months p.i. between the two groups but not at the 18 month time point. Two infected male mice had livers with severe hepatitis, and the liver samples were culture positive for H. marmotae. Serum IgG levels in the mice dosed with H. marmotae were elevated for the duration of the study. These results demonstrate that the woodchuck helicobacter can successfully colonize mice and cause enterohepatic disease. In the future, a mouse-adapted strain of H. marmotae could be selected to maximize colonization and lesion development. Such a woodchuck helicobacter-infected mouse model could be used to dissect potential mechanisms of microbial co-carcinogenesis involved in tumour development in woodchucks with WHV and in humans with hepatitis B virus.

Helicobacter species DNA in liver and gastric tissues in children and adolescents with chronic liver disease

OBJECTIVE

Enterohepatic Helicobacter species (EHS) have previously been found in adults with hepatobiliary diseases. Here, we report the prevalence of Helicobacter pylori and EHS in liver and gastric tissue in children and adolescents with chronic liver disease (CLD).

MATERIAL AND METHODS

Seventy-seven consecutive children and adolescents with CLD with or without ulcerative colitis or Crohn's disease (UC/CD) were investigated. Tissue samples were analysed using a Helicobacter genus-specific 16S rDNA polymerase chain reaction (PCR) assay and DNA-sequence analysis. Sera from 61 subjects were also analysed using enzyme immunoassay and immunoblotting.

RESULTS

The Helicobacter PCR was positive in 3/23 (13%) livers from patients with primary sclerosing cholangitis and UC, and in 1/2 livers from patients with autoimmune hepatitis (AIH) and UC. Sequenced PCR products matched the 16S rDNA of H. hepaticus, H. muridarum, H. canis, and H. pylori, respectively. H. ganmani and H. bilis were detected in gastric tissues from two AIH patients. H. hepaticus and H. pullorum were found in livers from two patients with acute liver failure and intrahepatic cholestasis. Antibody reactivity to Helicobacter cell-surface proteins was negative.

CONCLUSIONS

H. pylori and EHS can be detected in the livers of some patients with UC and concomitant liver disease, as well as in other children with liver diseases. Multicentre studies from different locations are needed to find out whether these bacteria play a pathogenetic role or whether their presence is an epiphenomenon.

Emesis in dogs: a review

Emesis is a common presenting sign in small animal practice. It requires a rational approach to management that is based upon a sound understanding of pathophysiology combined with logical decision making. This review, which assesses the weight of available evidence, outlines the physiology of the vomiting reflex, causes of emesis, the consequences of emesis and the approach to clinical management of the vomiting dog. The applicability of diagnostic testing modalities and the merit of traditional approaches to management, such as dietary changes, are discussed. The role and usefulness of both traditional and novel anti-emetic drugs is examined, including in specific circumstances such as following cytotoxic drug treatment. The review also examines areas in which common clinical practice is not necessarily supported by objective evidence and, as such, highlights questions worthy of further clinical research.

Hepatocellular carcinoma: prevalence and molecular pathogenesis of Helicobacter spp

Helicobacter pylori infection is one of the most common chronic bacterial infections in humans. The association of other Helicobacter spp. with extragastric diseases in animals is well established, and a role of these bacteria in human liver disease is becoming clearer. Several case-control studies have reported possible associations of Helicobacter spp. with various liver diseases, including hepatocellular carcinoma, which is the fifth most common type of carcinoma among men worldwide, and the eighth most common among women. Thus, it is important to understand molecular mechanisms that may lead to hepatotoxicity or hepatocellular dysfunction in which Helicobacter spp. may play a role in inducing malignant transformation of liver cells.

Helicobacter pylori promotes hepatic fibrosis in the animal model

Helicobacter pylori infection has been reported to be very common in patients with chronic liver diseases, including cirrhosis. To elucidate the pathological effect of H. pylori infection on the progression of hepatic fibrosis, C57BL/6 mice and Sprague-Dawley rats were orally inoculated with H. pylori, and hepatic fibrosis was induced with carbon tetrachloride (CCl(4)) administration. We observed the histopathological changes and the presence of H. pylori genes by PCR in the liver. Significant increase in the fibrotic score as well as in serum alanine aminotransferase and aspartate aminotransferase levels was shown in the CCl(4)+H. pylori group compared with that in the CCl(4)-treated group. Compared with the CCl(4)-treated group, alpha-smooth muscle actin and transforming growth factor-beta1 were enhanced; however, senescence marker protein-30, a multifunctional protein protecting hepatocytes against oxidative stress and apoptosis, was suppressed in the CCl(4)+H. pylori group. The 16S rRNA (400 bp) was demonstrated by PCR for H. pylori genes from genomic DNA extracted from the liver, and H. pylori-infected mice showed 93.8% (15 of 16) seropositivity by contrast with seronegativity in all H. pylori-noninfected mice. In addition, immunohistochemical study against H. pylori showed positive antigen fragments in the liver of the infected groups. Consequently, our data suggest that H. pylori infection could be an important contributing infectious factor to the development of liver cirrhosis.

Infectious hepatopathies in dogs and cats

This article serves to review the various infectious diseases that affect the liver primarily or as a part of systemic infection. Although bacterial infections are probably the most common cause of infectious hepatitis, the clinician should be aware of other potential organisms and other commonly involved systems. Therefore, this article includes a description of common bacterial, mycobacterial, viral, fungal, protozoal, parasitic, and rickettsial diseases in dogs and cats.

Detection of Helicobacter pylori in paraffin-embedded specimens from patients with chronic liver diseases, using the amplification method

Helicobacter DNA has been detected in the liver specimens of patients with various hepato-biliary diseases. The aim of this study was to investigate the presence of H. pylori DNA in the liver tissue of Iranian patients with chronic liver diseases (CLD). Genomic DNA was extracted from the paraffin sections of 46 liver biopsies of patients with CLD and 13 from patients with metastatic adenocarcinoma as a control group. Polymerase chain reaction (PCR) analysis was carried out using primers for H. pylori 16S rRNA and cagA genes. On analysis, 17 of the 46 patient samples were positive in H. pylori 16S rRNA PCR and 2 of the 13 were positive from the control group. None of the samples were positive for the cagA gene. This study showed the greater presence of H. pylori-like DNA in the liver samples from patients with CLD than in controls.

Spatial distribution of Helicobacter spp. in the gastrointestinal tract of dogs

BACKGROUND

In dogs, the gastric Helicobacter spp. have been well studied, but there is little information regarding the other parts of the alimentary system. We sought to determine the spatial distribution of Helicobacter spp. in the gastrointestinal tract and the hepatobiliary system of dogs using culture-independent methods.

MATERIALS AND METHODS

Samples of stomach, duodenum, ileum, cecum, colon, pancreas, liver, and bile from six dogs were evaluated for Helicobacter spp. by genus, gastric, and enterohepatic Helicobacter spp. Polymerase chain reaction, 16S rRNA gene sequence analysis, immunohistochemistry, and fluorescence in situ hybridization (FISH).

RESULTS

In the stomach, Helicobacter spp. DNA was detected in all six dogs, with H. bizzozeronii and H. felis identified by specific polymerase chain reaction. Helicobacter organisms were localized within the surface mucus, the lumen of gastric glands, and inside parietal cells. The small intestine harbored gastric and enterohepatic Helicobacter spp. DNA/antigen in low amounts. In the cecum and colon, Helicobacter spp. DNA, with highest similarity to H. bilis/flexispira taxon 8, H. cinaedi, and H. canis, was detected in all six dogs. Helicobacter organisms were localized at the mucosal surface and within the crypts. Gastric Helicobacter spp. DNA was detected occasionally in the large intestine, but no gastric Helicobacter spp. were present in clone libraries or detected by FISH.

CONCLUSIONS

This study demonstrates that in addition to the stomach, the large intestine of dogs is also abundantly colonized by Helicobacter spp. Additional studies are necessary to investigate the association between enterohepatic Helicobacter spp. and presence of intestinal inflammatory or proliferative disorders in dogs.

Primary hepatitis in dogs: a retrospective review (2002-2006)

BACKGROUND

Little is known about etiology, disease progression, treatment outcome, survival time, and factors affecting prognosis in dogs with primary hepatitis (PH).

OBJECTIVES

To review retrospectively different forms of hepatitis in a referral population, by the World Small Animal Veterinary Association Standardization criteria.

ANIMALS

One-hundred and one dogs examined for histologically confirmed PH between 2002 and 2006. Dogs with nonspecific reactive hepatitis were excluded.

METHODS

Retrospective study. Medical records were reviewed for prevalence, signalment, clinical and clinicopathologic manifestation, outcome, survival time, and prognostic factors for shortened survival.

RESULTS

PH occurred in 0.5% of dogs in this referral population. Acute (AH) and chronic hepatitis (CH) were diagnosed in 21 and 67 dogs, respectively. Progression from AH to CH occurred in 5/12 of the repeatedly sampled dogs. CH was idiopathic in 43 (64%) dogs, and was associated with copper accumulation in 24 (36%) dogs. Median survival time was longer in dogs with AH than in dogs with CH (either idiopathic or copper associated), and dogs with lobular dissecting hepatitis had the shortest survival time. Prognostic factors predicting shortened survival were associated with decompensated liver function and cirrhosis at initial examination.

CONCLUSIONS AND CLINICAL IMPORTANCE

The majority of PH in dogs is CH. Previous studies appear to have underestimated the etiologic role of copper in both AH and CH. Prognosis is reduced in dogs with hepatic cirrhosis or cirrhosis-related clinical findings. Further research into etiology and treatment effectiveness in all PH forms is needed.

Effects of Helicobacter infection on research: the case for eradication of Helicobacter from rodent research colonies

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.

Adherence, internalization, and persistence of Helicobacter pylori in hepatocytes

Although Helicobacter pylori have been identified in the liver, the role of Helicobacter sp. in human liver diseases remains unclear. This study explored whether H. pylori were internalized and could persist in hepatocytes. The majority of an inoculum of H. pylori (1 x 10(7) colony forming units) adhered to hepatocytes. Using the gentamicin invasion assay we found that approximately 2% were internalized and persisted following passage for more than 2 months. Electron microscopy confirmed the presence of intracellular Helicobacter. The number of adherent or internalized H. pylori was significantly greater with hepatocytes than with gastric epithelial cells (P < 0.05) and was also dependent on cag pathogenicity island (PAI), VacA, OipA, or BabA status. Transmission electron microscopy was used to confirm adherence and invasion of H. pylori into hepatocytes. Internalization of H. pylori was inhibited by antibodies to beta1-integrin receptors, genistein, and cytochalasin D (P < 0.05) consistent with beta1-integrin acting as a surface receptor with additional requirements for tyrosine kinase phosphorylation and actin polymerization. In summary, H. pylori both adhered to and invaded into hepatocytes in vitro, depending on the virulent factors, and persisted within hepatocytes during subcultures. beta1-integrin is likely a receptor involved in internalization of H. pylori into hepatocytes.

Disturbance of apoptosis and DNA synthesis by Helicobacter pylori infection of hepatocytes

We evaluated the effects of infection of hepatocytes with the well-characterized Helicobacter species, H. pylori. Cell number doubled during each 24 h period in mock cultures or following infection with H. pylori 401C (CagA-, VacA-, BabA-, OipA-) (P < 0.05). In contrast, infection with the more virulent H. pylori NCTC11637 (CagA+, VacA+, BabA+, OipA+) resulted in cell arrest (P < 0.05). Furthermore, NCTC11637 activated caspase-3 and increased DNA fragmentation 6.1 +/- 1.2 fold (P < 0.01) and the number of apoptotic bodies 9.4 +/- 3.5 fold (P < 0.01) compared to controls. The effect was greater than with the less virulent strain 401C (3.8 +/- 0.6 fold and 3.9 +/- 1.7, respectively, P < 0.05). Strain NCTC11637 at low concentrations increased cellular DNA synthesis 139 +/- 6% (P < 0.05) but decreased it to 16 +/- 7% (P < 0.01) at high concentrations. In contrast, strain 401C increased DNA synthesis 155 +/- 14% of controls (P < 0.05) at high concentrations. The presence of intracellular NCTC11637 within hepatocytes increased DNA fragmentation 3.0 +/- 0.4 fold (P < 0.01) greater than in controls. H. pylori infection resulted in strain-species-dependent effects on hepatocytes, and virulent strain caused cell arrest and apoptosis of infected hepatocytes.

Helicobacter canis bacteraemia in a 7-month-old child

On the basis of biochemical, phenotypic and 16S rRNA analyses, Helicobacter canis was isolated and identified from an otherwise healthy 7-month-old girl with intermittent fever. Blood cultures signalled bacterial growth after 5 days that was characterized as small gram-negative spiral rods. Subculturing on Colombia plates with 5% sheep blood, chocolate agar and brucella agar, aerobically and anaerobically as well as in a microaerophilic atmosphere, showed scanty growth after an additional 4 days. Secondarily seeded with fluid from the original bottle, the paediatric blood bottles repeatedly signalled growth after one night's incubation, whereas the conventially treated bottles did not support growth after 7 days' incubation. From the secondary seeded paediatric bottles a pure culture was isolated on chocolate agar plates, and identified as H. canis. This case indicates that blood culture systems should be compared and improved for their capacity to detect Helicobacter and related pathogenic bacteria species. Further studies are also needed to determine the importance of H. canis as a primary pathogen, and the role of cats in the possible zoonotic spread of H. canis to humans.

Helicobacter pylori and other Helicobacter species DNA in human bile samples from patients with various hepato-biliary diseases

AIM: To investigate the presence of Helicobacter species by nested PCR of 16S rRNA genes followed by the presence of Helicobacter pylori（H pylori）16S rRNA, ureA, cagA genes in bile obtained at endoscopic retrograde cholangio-pancreatography (ERCP) from 60 Indian subjects.

METHODS: Sixty bile samples were obtained from patients diagnosed with various hepato-biliary diseases and control subjects at ERCP. PCR analysis was carried out using primers for Helicobacter genus 16S rRNA gene and H pylori (16S rRNA, ureA and cagA) genes. Gastric H pylori status was also assessed from biopsies obtained at endoscopy from patients with various hepato-biliary diseases and controls. The control group mainly consisted of subjects with gastric disorders. Sequencing analysis was performed to confirm that PCR products with 16S rRNA and cagA primers were derived from H pylori.

RESULTS No Helicobacters were grown in culture from the bile samples. Helicobacter DNA was detected in bile of 96.7% and 6.6% of groups I and II respectively. Ten from group I were positive for 16S rRNA and ureA and 9 were positive for cagA gene. In contrast of the 2 from the control, 1 amplified with 16S rRNA, ureA and cagA primers used. The sequences of the 16S rRNA genes and cagA were 99% similar to Helicobacter pylori.

CONCLUSION: Helicobacters are associated with the pathogenesis of various hepato-biliary disorders.

The role of Helicobacter spp. in the pathogenesis of primary biliary cirrhosis and primary sclerosing cholangitis

Helicobacter species DNA has been detected in liver tissue of patients affected by primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). To investigate a potential causative relation between Helicobacter species and PBC/PSC, we compared the presence of Helicobacter species-specific DNA in liver tissue of patients with PBC/PSC (n=18/n=13) with those of a control group of patients with various liver diseases with known cause (n=29). A PCR with Helicobacter genus-specific 16S rRNA primers was performed on DNA isolated from paraffin embedded liver tissue. Control patients had hepatitis-B (n=9), alcoholic cirrhosis (n=14), or non-cirrhotic metabolic liver disease (n=6). There was no significant difference between the incidence of Helicobacter spp.-specific DNA in PBC/PSC (9/31; 29%) and the control group (10/29; 34%). Sequence analysis confirmed Helicobacter spp. DNA. Because Helicobacter spp. DNA can be found in approximately one-third of all samples tested, it is unlikely that PSC and PBC are caused by Helicobacter infection.

PCR screening for candidate etiological agents of canine hepatitis

PROBLEM ASSESSED

Hepatitis, either acute or chronic, is a relatively common hepatic disease in dogs. Several forms of canine hepatitis can occur, some with a defined cause, most cases have an unknown etiology. The similarities between canine hepatitis and human viral hepatitis suggest that canine hepatitis may have a viral etiology too.

OBJECTIVE

To test liver tissue of dogs with hepatitis for the presence of candidate agents based on their known association with hepatitis in other mammals.

METHODS AND APPROACH

The following infectious agents were tested by PCR: Hepadnaviridae, Helicobacter spp., Leptospira spp., Borrelia spp., hepatitis A virus, hepatitis C virus and hepatitis E virus. Also canine adenovirus and parvovirus were included. Ninety-eight liver tissue samples of dogs with various histologically diagnoses forms of hepatitis were tested. Primers were designed on conserved regions in the genome of each of these agents, to increase the likelihood of detection by PCR. To further increase sensitivity, nested PCRs for all agents were designed. Finally, for each agent a nested short primer PCR (SPP) was performed.

RESULTS

None of these agents were detected by nested PCR and nested SPP. However, in two acute hepatitis liver samples parvovirus was detected by nested PCR, and one of these was also detected by nested SPP.

CONCLUSIONS

Hepatitis in dogs is not caused by agents with high homology to known infectious agents that cause hepatitis in other species.

Detection of Helicobacter pylori in bile of cats

Lymphocytic cholangitis (LC) in cats is a biliary disease of unknown etiology. Helicobacter spp. were recently implicated in human primary sclerosing cholangitis (PSC) and primary biliary cirrhosis (PBC). Because of the similarities between PSC/PBC with LC, we hypothesized that Helicobacter spp. are involved in feline LC. A PCR with Helicobacter genus-specific 16S rRNA primers was performed on DNA isolated from feline bile samples. Four of the 15 (26%) LC samples were positive, whereas only 8/51 (16%) of non-LC samples were PCR positive (p=0.44). Sequence analysis of the amplicons revealed a 100% identity with the Helicobacter pylori specific DNA fragments. Our data suggest an etiological role of H. pylori in feline LC and that cats are a potential zoonotic reservoir.

A novel enterohepatic Helicobacter species 'Helicobacter mastomyrinus' isolated from the liver and intestine of rodents

BACKGROUND

A number of novel Helicobacter species have been isolated from both animals and humans. Many of these helicobacters colonize the lower gastrointestinal tract and hepatobiliary tract and are associated with diseases.

METHODS

A spiral-shaped bacterium, with bipolar single-sheathed flagella, was isolated from the liver and cecum of mastomys (the African rodent, Mastomys natalenis), from the feces and ceca of normal mice, and also from the cecum of a mouse with proctitis. 16S ribosomal RNA gene sequence analysis, restriction fragment length polymorphism (RFLP) and fluorophore-enhanced repetitive element polymerase chain reaction (FERP or rep-PCR) analysis were used to classify the organism.

RESULTS

The bacterium grew at 37 and 42 degrees C under microaerobic conditions, rapidly hydrolyzed urea, and was catalase and oxidase positive. It did not reduce nitrate to nitrite, and was resistant to cephalothin and nalidixic acid. Like many other enterohepatic Helicobacter species, this organism expressed cytolethal distending toxin and causes cell distention.

CONCLUSIONS

The organism was classified as a novel Helicobacter species for which we propose the name 'Helicobacter mastomyrinus'. Although 'H. mastomyrinus', like Helicobacter hepaticus and Helicobacter bilis, colonizes the liver of rodents, the pathogenic potential of this novel helicobacter is unknown.

Hepatitis with special reference to dogs. A review on the pathogenesis and infectious etiologies, including unpublished results of recent own studies

The causes of hepatitis in dogs are mostly unknown. Known causes of canine hepatitis are infectious (CAV-1), toxic (e.g. aflatoxin), and metabolic (copper accumulation). In order to understand the unknown causes, research in this field is necessary. Despite the marked progress in the knowledge on viral causes for human hepatitis, the involvement of infectious agents in the pathogenesis of hepatitis in the dog is still largely unknown. It is, like in human hepatitis, very likely that more than one causative infectious agent may cause hepatitis in the dog. This review presents the various forms of hepatitis in the dog, the known infectious and non-infectious causes of canine hepatitis, the infectious causes of hepatitis in man and other animals, and finally our recent infection and molecular studies to investigate possible infectious causes of canine hepatitis.

Chronic hepatitis in dogs: a review of current understanding of the aetiology, progression, and treatment

Chronic hepatitis is common in dogs in primary and referral practice but the cause is usually unknown. This paper reviews the literature on potential causes of chronic hepatitis in dogs (infectious, autoimmune, metabolic, toxic, and breed-associated) together with the literature on the progression of the disease and on treatments. This is compared with the current understanding of aetiology, progression, and treatment of chronic hepatitis in man. Unfortunately, little is known about the aetiology and progression of the canine disease and very few therapies have been subjected to critical trials. It is difficult therefore to draw conclusions about causes and effective treatment in dogs. Even the histological description for canine chronic hepatitis has yet to be standardised. Much research remains to be done and this review suggests some potential areas for future investigation.