Experimental induction of bacterial gastritis and gastric ulcer disease in gnotobiotic swine inoculated with porcine Helicobacter-like species

The role of Helicobacter suis, Fusobacterium gastrosuis, and the pars oesophageal microbiota in gastric ulceration in slaughter pigs receiving meal or pelleted feed

This study investigated the role of causative infectious agents in ulceration of the non-glandular part of the porcine stomach (pars oesophagea). In total, 150 stomachs from slaughter pigs were included, 75 from pigs that received a meal feed, 75 from pigs that received an equivalent pelleted feed with a smaller particle size. The pars oesophagea was macroscopically examined after slaughter. (q)PCR assays for H. suis, F. gastrosuis and H. pylori-like organisms were performed, as well as 16S rRNA sequencing for pars oesophagea microbiome analyses. All 150 pig stomachs showed lesions. F. gastrosuis was detected in 115 cases (77%) and H. suis in 117 cases (78%), with 92 cases (61%) of co-infection; H. pylori-like organisms were detected in one case. Higher infectious loads of H. suis increased the odds of severe gastric lesions (OR = 1.14, p = 0.038), while the presence of H. suis infection in the pyloric gland zone increased the probability of pars oesophageal erosions [16.4% (95% CI 0.6-32.2%)]. The causal effect of H. suis was mediated by decreased pars oesophageal microbiome diversity [-1.9% (95% CI - 5.0-1.2%)], increased abundances of Veillonella and Campylobacter spp., and decreased abundances of Lactobacillus, Escherichia-Shigella, and Enterobacteriaceae spp. Higher infectious loads of F. gastrosuis in the pars oesophagea decreased the odds of severe gastric lesions (OR = 0.8, p = 0.0014). Feed pelleting had no significant impact on the prevalence of severe gastric lesions (OR = 1.72, p = 0.28). H. suis infections are a risk factor for ulceration of the porcine pars oesophagea, probably mediated through alterations in pars oesophageal microbiome diversity and composition.

Molecular Detection of Metronidazole and Tetracycline Resistance Genes in Helicobacter pylori-Like Positive Gastric Samples from Pigs

Antimicrobial resistance is a major public health concern. The aim of this study was to assess the presence of antibiotic resistance genes, previously reported in Helicobacter pylori, in gastric samples of 36 pigs, in which DNA of H. pylori-like organisms had been detected. Based on PCR and sequencing analysis, two samples were positive for the 16S rRNA mutation gene, conferring tetracycline resistance, and one sample was positive for the frxA gene with a single nucleotide polymorphism, conferring metronidazole resistance. All three amplicons showed the highest homology with H. pylori-associated antibiotic resistance gene sequences. These findings indicate that acquired antimicrobial resistance may occur in H. pylori-like organisms associated with pigs.

Direct Detection of Antibiotic Resistance in Chinese Helicobacter pylori Clinical Isolates by Sequencing-Based Approach

Objective

The detection of Helicobacter pylori mutations that result in antimicrobial resistance can serve as a guideline of antimicrobial therapeutics and probably prevent the failure of clinical treatments. Evaluating the potential of Sanger sequencing to identify genetically resistant determinants in Helicobacter pylori clinical isolates will be important.

Methods

180 cultured strains have been tested using agar dilution for antibiotic susceptibility. NCBI BLAST was used to perform genotypic analysis on the sequencing data. Sanger sequencing was evaluated as an alternative method to detect resistant genotypes and susceptibility.

Results

By the conventional E-test, resistance to levofloxacin, amoxicillin, metronidazole, and clarithromycin was 67.3%, 15.1%, 96.4%, and 25.5%, respectively. In contrast, tetracycline had no resistance. Resistance to multiple drugs was observed in 8.12% of the strains. The genetic determinants of resistance to CLA was 23s rRNA, the determinants of resistance to amoxicillin was Pbp1, the determinants of resistance to metronidazole was rdxA, and the determinants of resistance to levofloxacin were GyrA and GyrB. However, there was no association of resistance in tetracycline.

Conclusion

We found increased rates of metronidazole antibiotic resistance, highlighting the necessity for alternative therapies and periodic evaluation. Sanger sequencing has proved to be highly effective and holds the potential to be implemented in policies catering to local treatments.

Helicobacter pylori-induced gastric pathology: insights from in vivo and ex vivo models

Gastric colonization with Helicobacter pylori induces diverse human pathological conditions, including superficial gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric adenocarcinoma and its precursors. The treatment of these conditions often relies on the eradication of H. pylori, an intervention that is increasingly difficult to achieve and that does not prevent disease progression in some contexts. There is, therefore, a pressing need to develop new experimental models of H. pylori-associated gastric pathology to support novel drug development in this field. Here, we review the current status of in vivo and ex vivo models of gastric H. pylori colonization, and of Helicobacter-induced gastric pathology, focusing on models of gastric pathology induced by H. pylori, Helicobacter felis and Helicobacter suis in rodents and large animals. We also discuss the more recent development of gastric organoid cultures from murine and human gastric tissue, as well as from human pluripotent stem cells, and the outcomes of H. pylori infection in these systems.

Gastric helicobacters in domestic animals and nonhuman primates and their significance for human health

Helicobacters other than Helicobacter pylori have been associated with gastritis, gastric ulcers, and gastric mucosa-associated lymphoid tissue lymphoma in humans. These very fastidious microorganisms with a typical large spiral-shaped morphology were provisionally designated "H. heilmannii," but in fact they comprise at least five different Helicobacter species, all of which are known to colonize the gastric mucosa of animals. H. suis, which has been isolated from the stomachs of pigs, is the most prevalent gastric non-H. pylori Helicobacter species in humans. Other gastric non-H. pylori helicobacters colonizing the human stomach are H. felis, H. salomonis, H. bizzozeronii, and the still-uncultivable "Candidatus Helicobacter heilmannii." These microorganisms are often detected in the stomachs of dogs and cats. "Candidatus Helicobacter bovis" is highly prevalent in the abomasums of cattle but has only occasionally been detected in the stomachs of humans. There are clear indications that gastric non-H. pylori Helicobacter infections in humans originate from animals, and it is likely that transmission to humans occurs through direct contact. Little is known about the virulence factors of these microorganisms. The recent successes with in vitro isolation of non-H. pylori helicobacters from domestic animals open new perspectives for studying these microorganisms and their interactions with the host.

Evaluation of the effects of porcine genogroup 1 torque teno virus in gnotobiotic swine

OBJECTIVE

To determine whether porcine genogroup 1 torque teno virus (g1-TTV) can infect and cause disease in gnotobiotic swine.

SAMPLE POPULATION

20 conventional baby pigs and 46 gnotobiotic baby pigs.

PROCEDURES

Porcine g1-TTV was transmitted from conventional swine to gnotobiotic pigs via pooled leukocyte-rich plasmas (n=18) that had positive results for g1-TTV DNA. Bone marrow-liver homogenates that had positive results for torque teno virus (TTV) were used in 4 serial passages in gnotobiotic pigs (2 pigs/passage). A pathogenesis experiment was conducted with in vivo passages of g1-TTV in various groups of gnotobiotic pigs.

RESULTS

All g1-TTV inoculated pigs had no clinical signs but developed interstitial pneumonia, transient thymic atrophy, membranous glomerulonephropathy, and modest lymphocytic to histiocytic infiltrates in the liver after inoculation with the TTV-containing tissue homogenate; these changes were not detected in uninoculated control pigs or pigs injected with tissue homogenate devoid of TTV DNAs. In situ hybridization was used to identify g1-TTV DNAs in bone marrow mononuclear cells.

CONCLUSIONS AND CLINICAL RELEVANCE

Analysis of these data revealed that porcine g1-TTV was readily transmitted to TTV-naïve swine and that infection was associated with characteristic pathologic changes in gnotobiotic pigs inoculated with g1-TTV. Thus, g1-TTV could be an unrecognized pathogenic viral infectious agent of swine. This indicated a directly associated induction of lesions attributable to TTV infection in swine for a virus of the genus Anellovirus.

Alterações histológicas da pars esophagea de suínos e sua relação com Helicobacter spp

A relação entre Helicobacter spp. e a presença de alterações histológicas na pars esophagea de suínos foi avaliada em 67 estômagos de animais em idade de abate. Para a identificação das helicobactérias, utilizou-se a técnica da PCR com primers específicos para o gênero Helicobacter. As alterações histológicas foram identificadas e classificadas como ulceração, erosão, degeneração epitelial, alongamento de papilas, hiperplasia, paraqueratose, intensidade do infiltrado inflamatório e aumento do número de folículos linfoides. As alterações mais frequentemente encontradas na pars esophagea foram a degeneração epitelial e o alongamento de papilas, observadas em 83,5% (n=56) das amostras analisadas. Em 77,5% (n=52) das amostras, observou-se paraqueratose e em 61,1% (n=41) hiperplasia epitelial. Quarenta e sete (70,1%) foram positivas na PCR para Helicobacter spp. Nessas amostras a erosão foi a lesão mais observada (40,2%), seguida de ulceração da mucosa (11,9%). Em 58,2% das amostras positivas na PCR, não foram observadas ulcerações de mucosa. Observou-se associação significativa (P=0,003) entre a presença de Helicobacter spp. e a degeneração epitelial da pars esophagea de suínos em idade de abate.

Cell proliferation in pathogenesis of esophagogastric lesions in pigs

Esophagogastric ulcer is an independent disease in swine that is characterized by ulcerous autodigestion of the cutaneous mucosa, which does not exhibit a tendency to recover, but, on the contrary, a tendency toward severe hemorrhaging, with a predominantly lethal outcome. Since it develops in the part of the stomach that is morphologically and functionally different from other glandular mucosa, it was questioned earlier whether it could be a peptic ulcer based on its nature. Spontaneous ulcers, usually of the stomach, commonly occur in many domestic animals. Some of these lesions are chronic and they may occur in either the glandular or squamous-lined regions of the stomach. As with the human disease, the pathogenesis in domestic animals is multifactorial, poorly understood, and variable between and within species. Environmental stress and dietary factors are very important in the ulcer disease in swine. It has been shown that the Helicobacter spp. is strongly associated with naturally occurring ulcer and preulcer lesions of the pars esophagea in swine, which raises the possibility that Helicobacter spp. is an important factor in the pathogenesis of these lesions. The dynamics of the development of esophagogastric ulcers imply hyperplastic lesions (parakeratosis and hyperkeratosis), keratolysis, erosions, peptic necrosis, and the development of ulcers with all the characteristics of peptic ulcerations in other localities. In addition, K6 is expressed in association with the mucosal changes. The pattern of the intermediate filaments of keratin suggests that epithelial proliferation, which leads to visible hyperkeratosis, constitutes the essence of gastric ulcers in swine.

Reproduction of severe gastroesophageal ulcers (GEU) in gnotobiotic swine infected with porcine Helicobacter pylori-like bacteria

Groups of gnotobiotic piglets were orally inoculated at 3 days of age with either Helicobacter heilmannii (Hh) or a newly described porcine-origin gastric Helicobacter pylori (Hp)-like bacterium. Three Hh-infected and 6 porcine Hp-like-infected swine were fed a milk replacement diet containing 5-10% (v/v) sterile corn syrup as a dietary source of fermentable carbohydrate. None of the piglets infected with Hh and supplemented with corn syrup developed gastric mucosal ulcers; 2 developed small erosive lesions in the pars esophagea. In contrast, all 6 dietary carbohydrate-supplemented Hp-like-infected swine developed severe gastroesophageal ulcers; 1 of these ex-sanguinated into the stomach and died before the end of the experiment. Four of these 6 piglets had grossly evident partially digested blood in the intestinal lumens, indicative of bleeding into the gastrointestinal tract from the stomach. These data suggest that a high carbohydrate diet and gastric colonization by porcine Hp-like bacteria facilitate development of clinically significant gastroesophageal ulcers.

Age-dependent seroprevalence of antibodies against aHelicobacter pylori–like organism andHelicobacter pyloriin commercially reared swine

OBJECTIVE

To determine the prevalence of antibodies against a swine-origin Helicobacter pylori-like organism (HPLO) and H pylori in conventionally reared swine.

ANIMALS

640 conventionally reared swine of various ages from 16 high-health farms in Canada, 20 sows from Ohio, and 35 gnotobiotic swine.

PROCEDURES

Blood was collected from the cranial vena cava. Sera were collected and tested via ELISA for antibodies against antigen prepared from a swine-origin HPLO and human H pylori strain 26695.

RESULTS

Antibodies reactive with a swine HPLO, H pylori, or both were detected in 483 of 640 swine from all 16 farms in western Canada. Seroprevalence varied with age and was low (5.6%) in suckling (<or= 4-week-old) swine and increasingly high in swine ranging from > 4 weeks old to adulthood.

CONCLUSIONS AND CLINICAL RELEVANCE

Findings suggested that colonization by a swine-origin HPLO, H pylori, or both and resultant seroconversion, like that of H pylori infection in humans, were common in commercial swine operations. Furthermore, data indicated that gastric infection was acquired at an early age. The relationships to gastric colonization by HPLOs and clinical manifestations of disease such as gastritis and gastroesophageal ulceration remain to be determined.

Extragastric manifestations of Helicobacter pylori infection--other Helicobacter species

Recent studies have indicated a strong link between Helicobacter pylori and idiopathic thrombocytopenic purpura and iron deficiency anemia. Interesting results have also been obtained for ischemic heart disease, though most putative associations between H. pylori infection and extragastric disease remain speculative. With regard to other Helicobacter species, Helicobacter felis has been shown to play a role in gastric carcinogenesis in mouse models. An increased susceptibility to cholesterol gallstone formation has been described in animals fed a lithogenic diet and infected with Helicobacter bilis, or co-infected with Helicobacter hepaticus and Helicobacter rodentium. Finally, enterohepatic Helicobacter species have also been exploited to better understand inflammatory bowel disease.

Isolation and preliminary characterization of a novel Helicobacter species from swine

OBJECTIVE

To determine whether a Helicobacter sp similar to Helicobacter pylori in the stomachs of humans could be isolated from the stomachs of pigs.

ANIMALS

4 young conventionally reared and 21 gnotobiotic pigs.

PROCEDURE

Gastric mucosal homogenates (10% wt/vol) from 4 young conventionally reared pigs were cultured on Skirrow medium under microaerophilic conditions to assess the presence of Helicobacter spp. Colonies with morphologic features compatible with Helicobacter organisms were selected, tested for urease activity, and subpassaged on Skirrow medium. Isolates were examined via SDS-PAGE electrophoresis and reciprocal western blot analyses involving convalescent sera from monoinfected gnotobiotic pigs.

RESULTS

Urease- and catalase-positive, gram-negative, microaerophilic, small, curved rod bacteria were isolated from the gastric mucosa of young healthy pigs. The first isolate (2662) was structurally and immunologically closely related to H pylori isolated from humans. The second isolate (1268) displayed an SDS-PAGE profile dissimilar to that of H pylori and isolate 2662, yet it shared limited immunologic cross-reactivity with these microbes.

CONCLUSIONS AND CLINICAL RELEVANCE

Findings of this study indicate that development of gastric mucosal ulcers and ulceration of the nonglandular pars esophagea in pigs may be associated with gastric colonization by swine-origin Helicobacter spp, which are similar to H pylori isolated from humans.