Detection of Helicobacter species in chronic liver disease and chronic inflammatory bowel disease

Helicobacter pullorum and Helicobacter canadensis: Etiology, pathogenicity, epidemiology, identification, and antibiotic resistance implicating food and public health

Nowadays, it is well-established that the consumption of poultry meat, especially chicken meat products has been drastically increasing. Even though more attentions are being paid to the major foodborne pathogens, it seems that scientists in the area of food safety and public health would prefer tackling the minor food borne zoonotic emerging or reemerging pathogens, namely Helicobacter species. Recently, understanding the novel aspects of zoonotic Enterohepatic Helicobacter species, including pathogenesis, isolation, identification, and genomic features is regarded as a serious challenge. In this regard, considerable attention is given to emerging elusive zoonotic Enterohepatic Helicobacter species, comprising Helicobacter pullorum and Helicobacter canadensis. In conclusion, the current review paper would attempt to elaborately summarize and somewhat compare the etiology, pathogenesis, cultivation process, identification, genotyping, and antimicrobial resistance profile of both H. pullorum and H. Canadensis. Further, H. pullorum has been introduced as the most significant food borne pathogen in chicken meat products.

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.

A report of nonexistence of the non-Helicobacter pylori Helicobacter species in Iranian patients suffering from inflammatory bowel disease

Inflammatory bowel disease is a chronic, relapsing-remitting gastrointestinal disorder which has become a serious global concern, and it imposes a great degree of health and economic burdens on communities worldwide. Although the presence of non-Helicobacter pylori Helicobacter (NHPH) microorganisms has been reported in various gastrointestinal disorders, their putative role in the pathogenesis of IBD has been a matter of controversy. The present study aimed to investigate the existence of gastric and enterohepatic NHPHs and their probable coinfection with H. pylori in IBD. Totally, 168 clinical specimens including 70 colonic biopsies and 98 fecal specimens were obtained from IBD patients. Genomic DNA was extracted from all samples, and its quality and concentration were assessed by β-globin PCR and spectrophotometry. The Helicobacter genus-specific PCR was performed using 16S rRNA gene. All samples were also tested for H. pylori infection by PCR of ureC gene fragment (glmM). The presence of NHPH was examined by using species-specific PCR assays. Based on PCR results, H. pylori was detected in 12.9% and 3.1% of colonic biopsies and fecal specimens, respectively. However, no statistically significant correlation was observed (P value > 0.05). We failed to find NHPH in both colonic biopsies and fecal specimens from IBD patients. Despite the fact that none of the IBD patients harbored the NHPH in the current work, further cohorts with larger sample size are required to determine the possible relationship between NHPH infection and IBD pathogenesis.

Association Between Helicobacter pylori Colonization and Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Various observational studies have examined a potential relationship between Helicobacter pylori colonization and inflammatory bowel diseases (IBDs); however, results are inconclusive. This systematic review evaluates articles reporting an association between human H. pylori colonization and IBD.

METHODS

A systematic search of studies was conducted to evaluate a possible relationship between H. pylori colonization and IBD. Seven databases and different types of gray literature were searched. After screening for relevant articles, selection and data extraction were done. After that, the data were analyzed, and pooled odds ratios (ORs) were calculated, using meta-analysis. Heterogeneity, sensitivity, and subgroups analyses were conducted. Funnel plots followed by Begg and Egger tests were done to assess the publication bias.

RESULTS

Among 58 studies, including 13,549 patients with IBD and 506,554 controls, the prevalence of H. pylori colonization was 22.74% and 36.30%, respectively. A significant negative association was observed between H. pylori colonization and IBD (pooled OR: 0.45, 95% confidence interval 0.39-0.53, P≤0.001). The random-effect model showed significant statistical heterogeneity in the included studies (I2=79%). No publication bias was observed. Among subgroups, ORs were notably different when the data were stratified by the age difference between patient and control group, and by study regions and/or continent. Finally, the meta-regression analysis showed significant results, in terms of the age difference and region variables.

CONCLUSIONS

In this meta-analysis, all statistical data support the theory that H. pylori has a protective role in IBD. However, more primary studies using proper methodology are needed to confirm this association.

Comparative genomics of Helicobacter pullorum from different countries

BACKGROUND

Helicobacter pullorum commonly colonized in the gastrointestinal tract of poultry and caused gastroenteritis. This bacterium could be transmitted to humans through contaminated food and caused colitis and hepatitis. Currently, the genetic characteristics of the H. pullorum were not recognized enough. In this study, the genomes of 23 H. pullorum strains from different counties were comparatively analyzed. Among them, H. pullorum 2013BJHL was the first isolated and reported in China.

RESULTS

The genomes of the studied strains were estimated to vary from 1.55 to 2.03 Mb, with a GC content of ~ 34%. 4064 pan genes and 1267 core genes were obtained from the core-pan genome analysis using the Roary pipeline. Core genome SNPs (cg-SNPs) were obtained using Snippy4 software. Two groups were identified with the phylogenetic analysis based on the cg-SNPs. Some adhesion-related, immune regulation, motility-related, antiphagocytosis-related, toxin-related and quorum sensing related genes were identified as virulence factors. APH(3')-IIIa, APH(2'')-If, and AAC(6')-Ie-APH(2'')-Ia were identified as antibiotic resistance genes among the H. pullorum genomes. cat, SAT-4 and tetO genes were only identified in 2013BJHL, and tet(C) was identified in MIT98-5489. MIC determination revealed that the 2013BJHL showed acquired resistance to ciprofloxacin, nalidixic acid, tetracycline, gentamicin, streptomycin and erythromycin, only sensitive to ampicillin. The antibiotic resistance genetic determinants on the 2013BJHL genome correlate well with observed antimicrobial susceptibility patterns. Two types of VI secretion system (T6SS) were identified in 52.2% (12/23) the studied strains.

CONCLUSION

In this study, we obtained the genetic characteristics of H. pullorum from different sources in the world. The comprehensive genetic characteristics of H. pullorum were first described. H. pullorum showed highly genetic diversity and two sub-types of T6SSs were first identified in H. pullorum. 2013BJHL was found to be multidrug resistant as it was resistant to at least three different antibiotic classes.

Helicobacter hepaticus infection-induced IL-33 promotes hepatic inflammation and fibrosis through ST2 signaling pathways in BALB/c mice

It has been documented that Helicobacter hepaticus (H. hepaticus) infection is linked to hepatic inflammation and fibrosis. Interleukin 33 (IL-33) is a cytokine involved in inflammatory and fibrotic diseases, but its relevance to H. hepaticus infection-induced liver inflammation and fibrosis is unknown. In this study, we found that the expression of IL-33 in mice liver was significantly induced by H. hepaticus infection at 24 weeks post infection (WPI). Immunohistochemistry analysis revealed that IL-33 was transferred from the nucleus to the cytoplasm due to infection. The quantitation of inflammatory cytokine and histopathology evaluation showed that IL-33 knockdown attenuated the H. hepaticus-induced hepatic inflammation and fibrosis. More importantly, H. hepaticus promoted the expression of the IL-33 receptor ST2 on cell surfaces, and the expression of ST2 then activated the expression nuclear factor-κB (p65), α-SMA, and Erk1/2. These observations provide novel insights into the pathogenic mechanism of hepatic inflammation and fibrosis during H. hepaticus infection.

Dual role of Helicobacter and Campylobacter species in IBD: a systematic review and meta-analysis

OBJECTIVE

To conduct a comprehensive global systematic review and meta-analysis on the association between Helicobacter pylori infection and IBD. As bacterial antigen cross-reactivity has been postulated to be involved in this association, published data on enterohepatic Helicobacter spp (EHS) and Campylobacter spp and IBD was also analysed.

DESIGN

Electronic databases were searched up to July 2015 for all case-control studies on H. pylori infection/EHS/Campylobacter spp and IBD. Pooled ORs (P-OR) and 95% CIs were obtained using the random effects model. Heterogeneity, sensitivity and stratified analyses were performed.

RESULTS

Analyses comprising patients with Crohn's disease (CD), UC and IBD unclassified (IBDU), showed a consistent negative association between gastric H. pylori infection and IBD (P-OR: 0.43, p value <1e-10). This association appears to be stronger in patients with CD (P-OR: 0.38, p value <1e-10) and IBDU (P-OR: 0.43, p value=0.008) than UC (P-OR: 0.53, p value <1e-10). Stratification by age, ethnicity and medications showed significant results. In contrast to gastric H. pylori, non H. pylori-EHS (P-OR: 2.62, p value=0.001) and Campylobacter spp, in particular C. concisus (P-OR: 3.76, p value=0.006) and C. showae (P-OR: 2.39, p value=0.027), increase IBD risk.

CONCLUSIONS

H. pylori infection is negatively associated with IBD regardless of ethnicity, age, H. pylori detection methods and previous use of aminosalicylates and corticosteroids. Antibiotics influenced the magnitude of this association. Closely related bacteria including EHS and Campylobacter spp increase the risk of IBD. These results infer that H. pylori might exert an immunomodulatory effect in IBD.

Genome Dynamics and Molecular Infection Epidemiology of Multidrug-Resistant Helicobacter pullorum Isolates Obtained from Broiler and Free-Range Chickens in India

Some life-threatening, foodborne, and zoonotic infections are transmitted through poultry birds. Inappropriate and indiscriminate use of antimicrobials in the livestock industry has led to an increased prevalence of multidrug-resistant bacteria with epidemic potential. Here, we present a functional molecular epidemiological analysis entailing the phenotypic and whole-genome sequence-based characterization of 11 H. pullorum isolates from broiler and free-range chickens sampled from retail wet markets in Hyderabad City, India. Antimicrobial susceptibility tests revealed all of the isolates to be resistant to multiple antibiotic classes such as fluoroquinolones, cephalosporins, sulfonamides, and macrolides. The isolates were also found to be extended-spectrum β-lactamase producers and were even resistant to clavulanic acid. Whole-genome sequencing and comparative genomic analysis of these isolates revealed the presence of five or six well-characterized antimicrobial resistance genes, including those encoding a resistance-nodulation-division efflux pump(s). Phylogenetic analysis combined with pan-genome analysis revealed a remarkable degree of genetic diversity among the isolates from free-range chickens; in contrast, a high degree of genetic similarity was observed among broiler chicken isolates. Comparative genomic analysis of all publicly available H. pullorum genomes, including our isolates (n = 16), together with the genomes of 17 other Helicobacter species, revealed a high number (8,560) of H. pullorum-specific protein-encoding genes, with an average of 535 such genes per isolate. In silico virulence screening identified 182 important virulence genes and also revealed high strain-specific gene content in isolates from free-range chickens (average, 34) compared to broiler chicken isolates. A significant prevalence of prophages (ranging from 1 to 9) and a significant presence of genomic islands (0 to 4) were observed in free-range and broiler chicken isolates. Taken together, these observations provide significant baseline data for functional molecular infection epidemiology of nonpyloric Helicobacter species such as H. pullorum by unraveling their evolution in chickens and their possible zoonotic transmission to humans.

IMPORTANCE

Globally, the poultry industry is expanding with an ever-growing consumer base for chicken meat. Given this, food-associated transmission of multidrug-resistant bacteria represents an important health care issue. Our study involves a critical baseline approach directed at genome sequence-based epidemiology and transmission dynamics of H. pullorum, a poultry pathogen having established zoonotic potential. We believe our studies would facilitate the development of surveillance systems that ensure the safety of food for humans and guide public health policies related to the use of antibiotics in animal feed in countries such as India. We sequenced 11 new genomes of H. pullorum as a part of this study. These genomes would provide much value in addition to the ongoing comparative genomic studies of helicobacters.

Biochar, Bentonite and Zeolite Supplemented Feeding of Layer Chickens Alters Intestinal Microbiota and Reduces Campylobacter Load

A range of feed supplements, including antibiotics, have been commonly used in poultry production to improve health and productivity. Alternative methods are needed to suppress pathogen loads and maintain productivity. As an alternative to antibiotics use, we investigated the ability of biochar, bentonite and zeolite as separate 4% feed additives, to selectively remove pathogens without reducing microbial richness and diversity in the gut. Neither biochar, bentonite nor zeolite made any significant alterations to the overall richness and diversity of intestinal bacterial community. However, reduction of some bacterial species, including some potential pathogens was detected. The microbiota of bentonite fed animals were lacking all members of the order Campylobacterales. Specifically, the following operational taxonomic units (OTUs) were absent: an OTU 100% identical to Campylobacter jejuni; an OTU 99% identical to Helicobacter pullorum; multiple Gallibacterium anatis (>97%) related OTUs; Bacteroides dorei (99%) and Clostridium aldenense (95%) related OTUs. Biochar and zeolite treatments had similar but milder effects compared to bentonite. Zeolite amended feed was also associated with significant reduction in the phylum Proteobacteria. All three additives showed potential for the control of major poultry zoonotic pathogens.

Association between Helicobacter spp. infections and hepatobiliary malignancies: a review

Hepatobiliary cancers are highly lethal cancers that comprise a spectrum of invasive carcinomas originating in the liver hepatocellular carcinoma, the bile ducts intrahepatic cholangiocarcinoma and extrahepatic cholangiocarcinoma, the gallbladder and the ampulla of Vater (collectively known as biliary tract cancers). These tumors account for approximately 13% of all annual cancer-related deaths worldwide and for 10%-20% of deaths from hepatobiliary malignancies. Cholangiocarcinoma (CCA) is a devastating disease that displays a poor survival rate for which few therapeutic options are available. Population genetics, geographical and environmental factors, cholelithiasis, obesity, parity, and endemic infection with liver flukes have been identified as risk factors that influence the development of biliary tract tumors. Other important factors affecting the carcinogenesis of these tumors include chronic inflammation, obstruction of the bile ducts, and impaired bile flow. It has been suggested that CCA is caused by infection with Helicobacter species, such as Helicobacter bilis and Helicobacter hepaticus, in a manner that is similar to the reported role of Helicobacter pylori in distal gastric cancer. Due to the difficulty in culturing these Helicobacter species, molecular methods, such as polymerase chain reaction and sequencing, or immunologic assays have become the methods of choice for diagnosis. However, clinical studies of benign or malignant biliary tract diseases revealed remarkable variability in the methods and the findings, and the use of uniform and validated techniques is needed.

Natural and experimental Helicobacter pullorum infection in Brown Norway rats

Helicobacter pullorum is an enterohepatic Helicobacter species (EHS) that was recently reported as a naturally acquired infection in mice. Faecal samples from 18 out of 20 Brown Norway (BN) rats, housed in the same barrier as the H. pullorum-infected mice, were positive for H. pullorum using species-specific PCR. In addition, we determined whether H. pullorum was able to persistently colonize the gastrointestinal tract and/or biliary tree and elicit tissue inflammation as well as a serum IgG response in BN rats. Six (four male, two female) 6-week-old, H. pullorum-negative BN rats were orally dosed with 4×10(8) c.f.u. of H. pullorum every other day for a total of three doses. At 2 weeks post-infection, all rats were H. pullorum-positive by faecal PCR. Five out of the six BN rats remained H. pullorum-positive for the entire 30 week study. PCR analysis of tissue collected at necropsy confirmed that the colon and caecum were the primary sites of H. pullorum colonization. Rats that were persistently colonized by H. pullorum had a sustained H. pullorum-specific IgG response measured by ELISA. Intestinal or hepatic pathology associated with H. pullorum infection was not noted. To our knowledge, this is the first report documenting that rats can be persistently colonized with an EHS that also infects humans.

Persistent Helicobacter pullorum colonization in C57BL/6NTac mice: a new mouse model for an emerging zoonosis

Helicobacter pullorum, an enterohepatic Helicobacter species, is associated with gastroenteritis and hepatobiliary disease in humans and chickens. Recently, a novel H. pullorum outbreak in barrier-maintained rats and mice was described. In this study, persistence of infection and serological responses were further evaluated in H. pullorum-infected female C57BL/6NTac and C3H/HeNTac mice obtained from the barrier outbreak. C57BL/6NTac mice (n=36) aged 10-58 weeks were confirmed to be chronically infected with H. pullorum by PCR or culture of caecum, colon and faeces, with no evidence of hepatic infection; two of three C3H/HeNTac mice cleared H. pullorum infection by 26 weeks of age. A quantitative PCR (qPCR) assay based on the cdtB gene specific to H. pullorum demonstrated that colonization was high in the caecum and colon at 10(4)-10(6) c.f.u. equivalents per µg host DNA, and decreased by several logs from 32 to 58 weeks of age. Infected mice were seropositive by ELISA, and H. pullorum-specific IgG levels decreased as colonization was lost over time in selected mice. Consistent with the lack of pathology associated with chronic infection of C57BL/6 mice with other murine enteric helicobacters, C57BL/6NTac and C3H/HeNTac mice infected with H. pullorum did not develop gross or histological lesions of the liver or gastrointestinal tract. The cdtB-based qPCR assay can be used in screening animals, food sources and environmental samples for H. pullorum, as this food-borne pathogen has zoonotic potential. These findings will also allow future studies in murine models to dissect potential pathogenic mechanisms for this emerging pathogen.

Hemorrhage-induced intestinal damage is complement-independent in Helicobacter hepaticus-infected mice

With more than half of the world population infected, Helicobacter infection is an important public health issue associated with gastrointestinal cancers and inflammatory bowel disease. Animal studies indicate that complement and oxidative stress play a role in Helicobacter infections. Hemorrhage (HS) induces tissue damage that is attenuated by blockade of either complement activation or oxidative stress products. Therefore, we hypothesized that chronic Helicobacter hepaticus infection would modulate HS-induced intestinal damage and inflammation. To test this hypothesis, we examined HS-induced jejunal damage and inflammation in uninfected and H. hepaticus-infected mice. Helicobacter hepaticus infection increased HS-induced midjejunal mucosal damage despite attenuating complement activation. In addition, infection alone increased chemokine secretion, changing the HS-induced neutrophil infiltration to a macrophage-mediated inflammatory response. The HS-induced macrophage infiltration correlated with increased secretion of tumor necrosis factor-α and nitric oxide in the infected mice. Together, these data indicate that Helicobacter infection modulates the mechanism of HS-induced intestinal damage and inflammation from a complement-mediated response to a macrophage response with elevated tumor necrosis factor-α and nitric oxide. These data indicate that chronic low-level infections change the response to trauma and should be considered when designing and administering therapeutics.

Commensal bacteria, traditional and opportunistic pathogens, dysbiosis and bacterial killing in inflammatory bowel diseases

PURPOSE OF REVIEW

The authors present evidence published during the past 2 years of the roles of commensal and pathogenic bacteria in the pathogenesis of the inflammatory bowel diseases.

RECENT FINDINGS

Rodent models conclusively implicate commensal enteric bacteria in chronic, immune-mediated, experimental colitis, and genetically determined defects in bacterial killing by innate immune cells are found in a subset of patients with Crohn's disease. There is no evidence that a single pathogen, including Mycobacterium avium subspecies paratuberculosis, causes Crohn's disease or ulcerative colitis. However, adherent/invasive Escherichia coli are associated with ileal Crohn's disease, with the mechanisms and genetics of adherent/invasive E. coli virulence being elucidated. Molecular characterization of the microbiota in patients with inflammatory bowel diseases reveals decreased biodiversity of commensal bacteria, most notably the phyla Bacteroidetes and Firmicutes, including the clinically relevant Faecalibacterium prausnitzii, and increased E. coli concentrations. VSL#3 is one probiotic preparation shown to be efficacious in certain clinical situations in small clinical trials.

SUMMARY

Further characterization of altered microbiota in patients with inflammatory bowel diseases and linking dysbiosis with host genetic alterations in immunoregulation, innate microbial killing and barrier function are critical, so that individualized treatments to increase beneficial commensals and their metabolic products (probiotic and prebiotic administration) and diminish deleterious species such as adherent/invasive E. coli can be tailored for defined patient subsets.

Cross-reactivity between immune responses to Helicobacter bilis and Helicobacter pylori in a population in Thailand at high risk of developing cholangiocarcinoma

Helicobacter bilis DNA has been detected in human tissue and is a candidate for etiologic investigations on the causes of hepatic and biliary tract diseases, but reliable serologic tests need to be developed in order to pursue such investigations. The scope of this study was to assess the specificity of two assays for H. bilis immune response allowing for H. pylori, and their cross-reactivity in a population in Thailand at high risk for cholangiocarcinoma. Plasma samples from 92 Thai volunteers were independently tested in two laboratories (Massachusetts Institute of Technology [MIT] and Lund). MIT performed three analyses of H. pylori and H. bilis based either on (i) outer membrane protein (OMP) with no preabsorption or on antigens derived from whole-cell sonicate before (ii) or after (iii) preabsorption with H. pylori sonicate protein. Lund used cell surface proteins from H. pylori and H. bilis as antigens. Testing for H. bilis was preabsorbed with a whole-cell lysate of H. pylori. More than 80% of the samples were positive for H. pylori in both laboratories. As tested by MIT, 58.7% (95% confidence interval, 47.9 to 68.9%) were positive for H. bilis by OMP and 44.5% (34.1 to 55.3%) were positive for H. bilis sonicate protein, but only 15.2% (8.6 to 24.2%) remained positive after preabsorption with H. pylori sonicate protein. Lund found 34.5% of the samples positive for H. bilis (22.0 to 41.0%), which was statistically compatible with all three MIT results. Serologic responses to OMPs of the two bacteria coincided in 66 and 45% of the samples in the MIT and Lund assays, respectively. We found high cross-reactivity between the immune responses to H. pylori and H. bilis antigens. More-specific H. bilis antigens need to be isolated to develop serologic tests suitable for epidemiological studies.