Gastroenteritis associated with Helicobacter pullorum

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.

Functional molecular characterization and the assessment of the transmission route of multidrug-resistant Helicobacter pullorum isolates from free-range and broiler chickens

BACKGROUND

Some of the life-threatening, food-borne, and zoonotic infections are transmitted through poultry birds. Inappropriate and irrational use of antimicrobials in the livestock industry has resulted in an increased incidence of multi-drug resistant bacteria of epidemic potentials.

MATERIALS AND METHODS

The adhesion and invasion properties of 11 free-range and broiler chicken derived Helicobacterpullorum isolates were evaluated. To examine the biofilm formation of H. pullorum isolates, crystal violet assay was performed. A quantitative assay of invasion-associated genes was carried out after infecting HepG2 cells with two different representative (broiler and free-range chicken) H. pullorum isolates, using RT-PCR assay. Furthermore, we investigated the prevalence of H. pullorum, Campylobacter jejuni and Salmonella spp. in chicken caeca and oviducts to determine the possibility of trans-ovarian transmission.

RESULTS

All H. pullorum isolates adhered to HepG2 cells significantly but a notable difference towards their invasion potential was observed between free-range and broiler chicken isolates wherein broiler isolates were found to be more invasive compared to free-range isolates. Furthermore, cdtB, flhA and flaB genes of H. pullorum were upregulated post infection of HepG2 cells, in broiler chicken isolates compared to free-range chicken isolates. Moreover, all isolates of H. pullorum were found to form biofilm on the liquid-air interface of the glass coverslips and sidewalls of the wells with similar propensities. Despite presence of H. pullorum and C. jejuni in high concentrations in the caecum, they were completely absent in oviduct samples, thus ruling out the possibility of vertical transmission of these bacterial species. In contrast, Salmonella spp. was found to be present in a significant proportion in the oviduct samples of egg-laying hens suggesting its vertical transmission.

CONCLUSIONS

Our findings suggest that H. pullorum, an emerging multi-drug resistant (MDR) pathogen could be transmitted from poultry sources to humans. In addition to this, its strong functional similarity with C. jejuni provides a firm basis for H. pullorum to be an emerging food-associated, MDR pathogenic bacterium that could pose risk to public health.

In Silico and In Vitro Analysis of Helicobacter pullorum Type Six Secretory Protein Hcp and Its Role in Bacterial Invasion and Pathogenesis

Helicobacter pullorum is a human zoonotic pathogen transmitted through poultry where it is associated with vibrionic hepatitis and colitis. Hemolysin co-regulated protein (Hcp) is an important structural as well as effector protein of type six secretory system; however, its role in H. pullorum invasion and pathogenesis has not been elucidated. In this study, we predicted the Helicobacter pullorum Hcp (HpuHcp) structure and identified Campylobacter jejuni Hcp (CjHcp) as its nearest homologue. Analysis of the predicted structure shows several common bacterial Hcp motifs like Protein kinase C phosphorylation site, Casein kinase II phosphorylation site, N-myristoylation site, cAMP-and cCGMP-dependent protein kinase phosphorylation site, N-glycosylation site. The presence of unique microbodies C-terminal targeting signal domain was present in HpuHcp which was seen for the first time in CjHcp. This could indicate that Hcp is a structural protein as well as a secretory protein. Moreover, the presence of a deamidase domain, similar to the tecA of Burkholderia cenocepacia an opportunistic pathogen, may help in bacterial internalization as it depolymerises the membranous actin by deamidation of the host cell Rho GTPases cdc42 and Rac1, which was supported by increased invasion of hepatocytes by Hcp-positive isolates.

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).

Effect of chitosan complexes on the bacterial community of cecum and productivity of broiler chickens

The search and development of natural biological additives that have a comprehensive effect as immunostimulants and improve digestion in poultry is relevant. This study was carried out at the Selection and Genetics Center “Zagorskoe EPH”. The control and experimental groups were formed of the 1-day-old Ross-308 cross broilers (35 heads in each). Six groups were formed. The broilers of the group No.1 (control) received basic feed (BF) with the addition of feed antibiotic Maxus. The group No.2 (control) received BF without feed antibiotic. The broilers of the group No.3 (experimental) received BF and the KH-1 chitosan complex. The group No.4 (experimental) received BF and the KHM chitosan complex with the addition of copper nanoparticles. The group No.5 (experimental) received BF and drinking preparation based on the KH-Aqua chitosan complex. The group No.6 (experimental) received BF and drinking preparation based on the KH-Aqua chitosan complex enriched with copper nanoparticles. The bacterial community of the gut cecum was analyzed using the molecular genetics method of next-generation sequencing (NGS). The addition of chitosan complexes (both supplemented with copper nanoparticles and in the drinking form) made it possible to obtain high livability of broilers with increased live body weight and decreased feed consumption per 1 kg of live body weight gain. The live body weight of 35-day-old broilers in the experimental groups was 2.96-5.70% higher than that of the control with a 5.86-8.23% decrease in feed consumption per 1 kg of live body weight gain. The results of NGS showed that the effect of chitosan complexes on the regulation of the composition of the microbiome of broilers’ cecum was predominantly positive. There was an up to 4.4-fold increase in the content of representatives of the normoflora, bacteria of the family Lactobacillaceae. The number of bacteria of genus Helicobacter, among which pathogens are often found, in the experimental groups was 2.6-33.3 times lower than in the group received antibiotics. So, the chitosan complexes were proved to be valuable supplements for poultry.

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.

Nitrosative stress defences of the enterohepatic pathogenic bacterium Helicobacter pullorum

Helicobacter pullorum is an avian bacterium that causes gastroenteritis, intestinal bowel and hepatobiliary diseases in humans. Although H. pullorum has been shown to activate the mammalian innate immunity with release of nitric oxide (NO), the proteins that afford protection against NO and reactive nitrogen species (RNS) remain unknown. Here several protein candidates of H. pullorum, namely a truncated (TrHb) and a single domain haemoglobin (SdHb), and three peroxiredoxin-like proteins (Prx1, Prx2 and Prx3) were investigated. We report that the two haemoglobin genes are induced by RNS, and that SdHb confers resistance to nitrosative stress both in vitro and in macrophages. For peroxiredoxins, the prx2 and prx3 expression is enhanced by peroxynitrite and hydrogen peroxide, respectively. Mutation of prx1 does not alter the resistance to these stresses, while the single ∆prx2 and double ∆prx1∆prx2 mutants have decreased viability. To corroborate the physiological data, the biochemical analysis of the five recombinant enzymes was done, namely by stopped-flow spectrophotometry. It is shown that H. pullorum SdHb reacts with NO much more quickly than TrHb, and that the three Prxs react promptly with peroxynitrite, Prx3 displaying the highest reactivity. Altogether, the results unveil SdHb and Prx3 as major protective systems of H. pullorum against nitrosative stress.

Helicobacter pullorum: An Emerging Zoonotic Pathogen

Helicobacter pullorum (H.pullorum) commonly colonizes the gastrointestinal tract of poultry causing gastroenteritis. The bacterium may be transmitted to humans through contaminated meat where it has been associated with colitis and hepatitis. Despite the high prevalence of H. pullorum observed in poultry, little is known about the mechanisms by which this bacterium establishes infection in host and its virulence determinants. In this article we aim to provide an overview of this emerging zoonotic pathogen; its general characteristics, hosts, prevalence, and transmission as well as its pathogenic potential. We also discuss possible control strategies and risk of disease emergence.

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.

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.

Pathogenic properties of enterohepatic Helicobacter spp. isolated from rhesus macaques with intestinal adenocarcinoma

Considerable progress has been made in understanding the roles of Helicobacter pylori in inflammation and gastric cancer; however, far less is known about the roles of enterohepatic Helicobacter species (EHS) in carcinogenesis and their zoonotic or pathogenic potential. We determined the prevalence of EHS infection in a cohort of geriatric rhesus monkeys in which intestinal adenocarcinoma (IAC) is common and investigated the association between EHS infection and IAC. The cohort consisted of 36 animals, 14 of which (age 26-35 years) had IAC. Of the 36 rhesus, 35 (97%) were positive for EHS using PCR or bacterial isolation from faeces, colonic or tumour tissues. Only a single rhesus, which had IAC, was negative for EHS by all detection methods. The EHS identified by 16S rRNA sequencing in this study were from three Helicobacter taxa: Helicobacter macacae (previously rhesus monkey taxon 1), Helicobacter sp. rhesus monkey taxon 2, previously described from strain MIT 99-5507, and Helicobacter sp. rhesus monkey taxon 4, related to Helicobacter fennelliae. Thirteen of 14 monkeys with IAC were positive for either H. macacae (7/13, 54%), EHS rhesus monkey taxon 4 (4/13, 31%) or a mixture of the two EHS (2/13, 15%). These results indicate that EHS are prevalent among aged rhesus macaques with IAC. Using Helicobacter genus-specific florescent in situ hybridization, EHS were detected on the surface of colonic epithelia of infected monkeys. All Helicobacter isolates, including H. macacae, effectively adhered to, invaded, and significantly induced proinflammatory genes, including IL-8, IL-6, TNF-α and iNOS, while downregulating genes involved in the function of inflammasomes, particularly IL-1β, CASPASE-1, NRLP3, NLRP6 and NLRC4 in the human colonic T84 cell line (P<0.0001). These results suggest that EHS may represent an aetiological agent mediating diarrhoea, chronic inflammation, and possibly intestinal cancer in non-human primates, and may play a role in similar disease syndromes in humans. Downregulation of inflammasome function may represent an EHS strategy for long-term persistence in the host and play a role in inducing pathological changes in the host's lower bowel.

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.

Enterohepatic helicobacter in ulcerative colitis: potential pathogenic entities?

BACKGROUND

Changes in bacterial populations termed "dysbiosis" are thought central to ulcerative colitis (UC) pathogenesis. In particular, the possibility that novel Helicobacter organisms play a role in human UC has been debated but not comprehensively investigated. The aim of this study was to develop a molecular approach to investigate the presence of Helicobacter organisms in adults with and without UC.

METHODOLOGY/PRINCIPAL FINDINGS

A dual molecular approach to detect Helicobacter was developed. Oligonucleotide probes against the genus Helicobacter were designed and optimised alongside a validation of published H. pylori probes. A comprehensive evaluation of Helicobacter genus and H. pylori PCR primers was also undertaken. The combined approach was then assessed in a range of gastrointestinal samples prior to assessment of a UC cohort. Archival colonic samples were available from 106 individuals for FISH analysis (57 with UC and 49 non-IBD controls). A further 118 individuals were collected prospectively for dual FISH and PCR analysis (86 UC and 32 non-IBD controls). An additional 27 non-IBD controls were available for PCR analysis. All Helicobacter PCR-positive samples were sequenced. The association between Helicobacter and each study group was statistically analysed using the Pearson Chi Squared 2 tailed test. Helicobacter genus PCR positivity was significantly higher in UC than controls (32 of 77 versus 11 of 59, p = 0.004). Sequence analysis indicated enterohepatic Helicobacter species prevalence was significantly higher in the UC group compared to the control group (30 of 77 versus 2 of 59, p<0.0001). PCR and FISH results were concordant in 74 (67.9%) of subjects. The majority of discordant results were attributable to a higher positivity rate with FISH than PCR.

CONCLUSIONS/SIGNIFICANCE

Helicobacter organisms warrant consideration as potential pathogenic entities in UC. Isolation of these organisms from colonic tissue is needed to enable interrogation of pathogenicity against established criteria.

Prevalence of Helicobacter pullorum in conventional, organic, and free-range broilers and typing of isolates

Helicobacter pullorum represents a potential food-borne pathogen, and avian species appear to be a relevant reservoir of this organism. In this study, the prevalence of H. pullorum was investigated at 30 conventional farms where 169 ceca from 34 flocks were tested, at eight organic farms where 39 ceca from eight flocks were tested, and at seven free-range farms where 40 ceca from eight flocks were tested. All of the ceca were obtained from healthy broiler chickens. Moreover, amplified fragment length polymorphism, pulsed-field gel electrophoresis, and automated ribotyping were employed to estimate the levels of genetic variability of H. pullorum broiler isolates within and between flocks. Overall, Gram-negative, slender, curved rods, identified as H. pullorum by PCR, were isolated at 93.3% of the farms tested. The percentage of positive free-range farms (54.2%) was significantly lower than that of conventional (100%) or organic (100%) farms (P < 0.001). The level of within-flock genetic variability, calculated as the number of flocks colonized by isolates genetically different by all of the typing methods, was 34.9%. Isolates showing identical profiles by each typing method were observed in 11.6% of the flocks, but they were never detected between flocks. However, groups of isolates clustered together with an overall similarity level of ≥85%. Our results suggest that even though a high level of genetic variability is attributable to H. pullorum broiler isolates, their hierarchical genotyping produces data useful for epidemiological investigations.

Could Helicobacter organisms cause inflammatory bowel disease?

The discovery of Helicobacter pylori sparked a revolution in the understanding and management of peptic ulcer disease and gastric cancer. Other Helicobacter species are recognized as important pathogenic agents in colitic diseases of rodents and primates, in particular Helicobacter bilis, Helicobacter fennelliae, Helicobacter hepaticus and Helicobacter trogontum. Helicobacter bilis and H. hepaticus are now routinely used to initiate rodent models of inflammatory bowel disease (IBD), particularly in immunocompromised hosts. Molecular evidence exists linking various non-pylori Helicobacter spp. with human IBD; however, attempts to culture organisms in this disease cohort have proved unsuccessful to date. Attributing causation has therefore proved elusive. Seven enterohepatic, non-pylori Helicobacter organisms have been successfully cultured from humans, namely Helicobacter canadensis, Helicobacter canis, Helicobacter cinaedi, H. fennelliae, Helicobacter pullorum, Helicobacter winghamensis and Helicobacter sp. flexispira taxon 8 (now classified as H. bilis). Of these, H. cinaedi and H. fennelliae are the closest to fulfilling Koch's postulates as causative agents in homosexual proctitis. The possibility that novel Helicobacter organisms have a role in the initiation of human IBD warrants further consideration and targeted investigations.

Diversity of caecal bacteria is altered in interleukin-10 gene-deficient mice before and after colitis onset and when fed polyunsaturated fatty acids

Interleukin-10 gene-deficient (Il10(-/-)) mice show a hyper-reaction to normal intestinal bacteria and develop spontaneous colitis similar to that of human Crohn's disease when raised under conventional (but not germ-free) conditions. The lack of IL10 protein in these mice leads to changes in intestinal metabolic and signalling processes. The first aim of this study was to identify changes in the bacterial community of the caeca at 7 weeks of age (preclinical colitis) and at 12 weeks of age (when clinical signs of colitis are present), and establish if there were any changes that could be associated with the mouse genotype. We have previously shown that dietary n-3 and n-6 polyunsaturated fatty acids (PUFA) have anti-inflammatory effects and affect colonic gene expression profiles in Il10(-/-) mice; therefore, we also aimed to test the effect of the n-3 PUFA eicosapentaenoic acid (EPA) and the n-6 PUFA arachidonic acid (AA) on the bacterial community of caeca in both Il10(-/-) and C57 mice fed these diets. The lower number of caecal bacteria observed before colitis (7 weeks of age) in Il10(-/-) compared to C57 mice suggests differences in the intestinal bacteria that might be associated with the genotype, and this could contribute to the development of colitis in this mouse model. The number and diversity of caecal bacteria increased after the onset of colitis (12 weeks of age). The increase in caecal Escherichia coli numbers in both inflamed Il10(-/-) and healthy C57 mice might be attributed to the dietary PUFA (especially dietary AA), and thus not be a cause of colitis development. A possible protective effect of E. coli mediated by PUFA supplementation and associated changes in the bacterial environment could be a subject for further investigation to define the mode of action of PUFA in colitis.

Helicobacter pullorum outbreak in C57BL/6NTac and C3H/HeNTac barrier-maintained mice

Helicobacter pullorum is a bacterial pathogen in humans. By using microaerobic culture techniques, H. pullorum was isolated from the feces of barrier-maintained mice and identified, on the basis of biochemical, restriction fragment length polymorphism, and 16S rRNA gene sequence analyses. This finding presents an opportunity to study H. pullorum pathogenesis in mice.

Association between entero-hepatic Helicobacter species and Crohn's disease: a prospective cross-sectional study

BACKGROUND

The pathogenesis of Crohn's disease (CD) involved microbial factors. Some Helicobacter species, the so-called entero-hepatic Helicobacters (EHH), can naturally colonize the intestinal surface and have been detected in humans. Aim To look for an association between CD and the presence of EHH DNA in intestinal biopsies.

METHODS

Two groups of patients were included prospectively in a multicentre cross-sectional study: CD patients with an endoscopic post-operative recurrence within 2 years following a surgical resection and controls screened for colorectal polyps or cancer. Intestinal biopsies were taken for Helicobacter culture and Helicobacter 16S DNA detection. If positive, the EHH species were identified with specific PCRs, sequencing and denaturing gradient gel electrophoresis.

RESULTS

In the 165 included patients (73 CD and 92 controls), Helicobacter cultures were negative. PCR was positive in 44% of CD and 47% of controls. After age-adjustment, CD was significantly associated with EHH in intestinal biopsies (OR = 2.58; 95%CI: 1.04-6.67). All EHH species detected were identified as Helicobacter pullorum and the closely related species Helicobacter canadensis.

CONCLUSION

Crohn's disease is associated with the presence of EHH species DNA in intestinal biopsies after adjustment for age. Whether these species play a role in the pathophysiology of CD remains to be determined.

N-linked glycosylation in bacteria: an unexpected application

Traditionally, glycoproteins have been considered the exclusive property of eukaryotes and archaea, but it is now evident that glycoproteins are found in all domains of life. In recent years N-linked glycosylation among some epsilon-proteobacteria has emerged as a new and exciting research area and represents a useful model to understand this complex process in simple, genetically tractable bacteria. Above all, the transfer of N-linked glycosylation systems to the work-horse bacterium, Escherichia coli, has enabled, for the first time, the production of recombinant glycoproteins. This has potentially provided the option for tailor-made glycoproteins and has opened up the field of glycoengineering, particularly with respect to the development of glycoconjugate vaccines.

Complete nucleotide sequence of the gyrA gene of Helicobacter pullorum and identification of a point mutation leading to ciprofloxacin resistance in poultry isolates

To assess the molecular basis of nalidixic acid and ciprofloxacin resistance in Helicobacter pullorum, the gyrA gene of H. pullorum CIP 104787T was sequenced. In addition, 9 isolates (2 susceptible to ciprofloxacin and resistant to nalidixic acid, 3 susceptible and 4 resistant to both antibiotics) were selected from 44 poultry isolates and the nucleotide sequences of their quinolone resistance-determining regions (QRDRs) were compared. The 2490 bp gyrA gene showed an open reading frame encoding a polypeptide of 829 amino acids. The deduced amino acid sequence of gyrA showed>or=72% identity to Helicobacter hepaticus, Helicobacter pylori and Wolinella succinogenes. Moreover, >or=98% amino acid sequence identity was found comparing the QRDR of the H. pullorum type strain with the QRDRs of the aforementioned bacterial species. All ciprofloxacin-resistant poultry isolates showed an ACA-->ATA (Thr-->Ile) substitution at codon 84 of gyrA, corresponding to codons 86, 87 and 83 of Campylobacter jejuni, H. pylori and Escherichia coli gyrA genes, respectively. This substitution was functionally confirmed to be associated with the ciprofloxacin-resistant phenotype of poultry isolates. This is the first report describing the complete 2490 bp nucleotide sequence of H. pullorum gyrA and confirming the involvement of the Thr84Ile substitution of GyrA in ciprofloxacin resistance of H. pullorum.

Occurrence and antibiotic susceptibility of Helicobacter pullorum from broiler chickens and commercial laying hens in Italy

In 2005, in order to investigate the occurrence of Helicobacter pullorum in poultry, the caecal contents collected from a total of 60 animals intensively reared in Italy on 15 different farms (9 farms of broiler chicken and 6 of laying hens) were examined at the slaughterhouse. A modified Steele-McDermott membrane filter method was used. Small, greyish-white colonies of Gram-negative, gently curved, slender rod bacteria were preliminarily identified as H. pullorum by a Polymerase Chain Reaction (PCR) assay based on 16S rRNA and were then subjected to an ApaLI digestion assay to distinguish H. pullorum from Helicobacter canadensis. One isolate from each farm was phenotypically characterized by biochemical methods and 1D SDS-PAGE analysis of whole cell proteins; antibiotic susceptibility was also tested. According to the PCR and PCR-RFLP results, all the animals examined were positive for H. pullorum. The 1D SDS-PAGE whole protein profile analysis showed high similarity among the 15 isolates tested. A monomodal distribution for the Minimum Inhibitory Concentrations (MICs) was found for ampicillin, chloramphenicol, gentamicin and tetracycline. For erythromycin and ciprofloxacin, a bimodal trend having a second peak at >128 micro(-1) and 32 micro(-1) was found. The isolation method used in this study seems to be highly suitable for isolating H. pullorum from chicken caecal contents. Moreover, the detection of a high number of colonies phenotypically similar to H. pullorum suggests that this microorganism, when present, colonizes the caecum at high concentration.

Relationship between the severity of hepatitis C virus-related liver disease and the presence of Helicobacter species in the liver: A prospective study

AIM: To determine the presence of Helicobacter species DNA in the liver of chronic hepatitis C (CHC) patients with and without cirrhosis as compared to controls, and to identify the bacterial species involved.

METHODS: Seventy-nine consecutive patients (HBV and HIV negative) with a liver sample obtained after liver biopsy or hepatic resection were studied: 41 with CHC without cirrhosis, 12 with CHC and cirrhosis, and 26 controls (HCV negative). Polymerase chain reactions (PCRs) targeting Helicobacter 16S rDNA and species-specific were performed on DNA extracted from the liver. A gastric infection with H pylori was determined by serology and confirmed by ¹³C-urea breath test.

RESULTS: Overall, Helicobacter 16S rDNA was found in 16 patients (20.2%). Although positive cases tended to be higher in CHC patients with cirrhosis (41.6%) than in those without cirrhosis (17.0%) or in controls (15.4%), the difference was not statistically significant (P = 0.08). H pylori-like DNA was identified in 12 cases and H. pullorum DNA in 2, while 2 cases remained unidenti-fied. Gastric infection with H pylori was found in only 2 of these patients.

CONCLUSION: Our results do not confirm the associ-ation of Helicobacter species DNA in the liver of CHC patients with advanced liver disease. The lack of correlation between positive H pylori serology and the presence of H pylori-like DNA in the liver may indicate the presence of a variant of this species.

Tissue Tropism of Helicobacter pullorum in Specific Pathogen-Free Chickens Determined by Culture and Nucleic Acid Detection

Three-day-old specific pathogen-free chickens (n = 24) located in isolators were inoculated orally with Helicobacter pullorum. One group (n = 12) was infected with a H. pullorum field isolate from human origin, another one (n = 12) with the American Type Culture Collection H. pullorum reference isolate 51801 originating from chickens. Both isolates were positive for cytolethal distending toxin, investigated using a polymerase chain reaction (PCR). A third group (n = 4) was kept as a negative control. Starting on day 7 of life, birds from each group were euthanatized at different time points up to 35 days. Various organ samples were taken aseptically and processed by culture and a H. pullorum-specific PCR. In the group infected with the human isolate the nucleic acid of H. pullorum was detected in the caecal tonsils and caeca of 12 and 11 birds, respectively. Live bacteria were cultivated from the caecal tonsils and caeca of five birds 24 and 31 days postinfection. Live bacteria were also isolated from the heart of one bird, whereas PCR had to be used to detect the nucleic acid of H. pullorum in the gallbladder of four birds. No live bacteria were reisolated at any time from birds infected with the avian isolate, but bacterial nucleic acid was detected in the caeca of five birds and in the gallbladder of one. In both groups neither live H. pullorum nor its nucleic acid were detected in the liver, spleen, and duodenum. Compared to the avian H. pullorum isolate the human isolate proved to be more invasive. No obvious clinical symptoms or disease was seen in the chickens during the entire experiment. The reisolation of live bacteria at the end of the experiments indicates that H. pullorum could enter the food chain even after early infection in birds. Furthermore, PCR was demonstrated to be helpful in tracing these fastidious bacteria.

Detection and identification of food-borne pathogens of the genera Campylobacter, Arcobacter and Helicobacter by multiplex PCR in poultry and poultry products

The objective of this study was to develop a multiplex polymerase chain reaction (PCR) to detect and differentiate food-borne pathogens of the three genera Campylobacter, Arcobacter and Helicobacter in a single step procedure. One common reverse primer and three genus-specific forward primers were designed by hybridizing to the 16S rRNA of selected reference strains. Besides the species with significance as food-borne pathogens isolated from poultry meat--Campylobacter jejuni, Campylobacter coli, Arcobacter butzleri and Helicobacter pullorum--several other members of these genera were tested to determine the specificity of the designed multiplex PCR. In total, 20 ATCC and NCTC reference strains of Campyobacter, Arcobacter and Helicobacter were used to evaluate the PCR. Specific amplificates were obtained from all thermophilic species of Campylobacter as well as from species of Arcobacter and Helicobacter. No amplification product was obtained from the non-thermophilic Campylobacter, C. hyointestinalis and C. fetus. Furthermore, a total of 43 field strains of the three genera isolated from poultry, pigs, cattle and humans were investigated using this PCR. To confirm the classification of 10 H. pullorum strains the 16S rRNAs were sequenced. The developed PCR is a helpful diagnostic tool to detect and differentiate Campylobacter, Arcobacter and Helicobacter isolated from poultry and poultry products.

Helicobacter pullorum in chickens, Belgium

A total of 110 broilers from 11 flocks were tested for Helicobacter pullorum by polymerase chain reaction; positive samples were reexamined with a conventional isolation method. H. pullorum isolates were examined by amplified fragment length polymorphism (AFLP) fingerprinting for interstrain genetic diversity and relatedness. Sixteen isolates from cecal samples from 2 different flocks were obtained. AFLP analysis showed that these isolates and 4 additional isolates from a different flock clustered according to their origin, which indicates that H. pullorum colonization may occur with a single strain that disseminates throughout the flock. Strains isolated from different hosts or geographic sources displayed a distinctive pattern. H. pullorum is present in approximately one third of live chickens in Belgium and may represent a risk to human health.

Prevalence of Helicobacter pullorum among patients with gastrointestinal disease and clinically healthy persons

Feces from 531 patients with gastroenteritis and from 100 clinically healthy individuals were tested for Helicobacter pullorum by use of PCR. Samples positive by PCR were qualified for isolation. H. pullorum DNA was demonstrated to be present in feces from 4.3% of patients with gastrointestinal disease but also in feces from 4.0% of clinically healthy persons. One strain was isolated from one patient with gastrointestinal disease.

Expression of matrix metalloprotease-2, -7 and -9 on human colon, liver and bile duct cell lines by enteric and gastricHelicobacterspecies

Gastric and enteric Helicobacter species have been associated with malignant and inflammatory diseases of the stomach, liver, gall bladder and intestine. Matrix metalloproteinases (MMPs) participate in degradation of extracellular matrix, which allows bacteria to come in contact with and interact with the cells. Enhanced level of MMPs facilitates metastasis and cell invasion of tumor cells by removal of physical barriers, as well as modulation of biologic activities of the proteins residing in the extracellular matrix. The aim of this study was to evaluate the effect of gastric and enteric Helicobacter on induction of MMPs in hepatocytes and epithelial cells of gall bladder and colon. Human hepatocytes HepG2, gall bladder epithelial cells TFK-1, and colon epithelial cells HT29 were infected with strains of H. pylori cagA+, cagE+, H. pylori cagA-, cagE-, H. pullorum, H. cholecystus, H. bilis and H. hepaticus. Protein levels of MMPs were analyzed by enzyme-linked immunosorbent assay and immunohistochemistry. Reverse transcription-quantitative polymerase chain reaction was used to study mRNA levels. Increased expression of MMP-2 and MMP-9 was observed on HepG2, TFK-1 and HT29 infected with H. pylori cagA+, cagE+ and H. cholecystus strains. H. pylori cagA+, cagE+, H. cholecystus, H. pullorum, H. bilis and H. hepaticus strains increased expression of MMP-7 on HT29, compared to uninfected control cells. The effect of MMP upregulation on HepG2, TFK-1 and HT29 was bacterial dose dependent. H. pylori cagA-, cagE- strain did not increase expression of MMPs. Inducible MMPs on colon and bile duct epithelial cells as well as hepatocytes may play an important role in facilitating invasion and progression of cancer by Helicobacter species colonizing the hepatobiliary and gastrointestinal tract.

Detection of Helicobacter species DNA by quantitative PCR in the gastrointestinal tract of healthy individuals and of patients with inflammatory bowel disease

In many animal species different intestinal Helicobacter species have been described and a few species are associated with intestinal infection. In humans, the only member of the Helicobacter family which is well described in literature is Helicobacter pylori. No other Helicobacter-associated diseases have definitely been shown in humans. We developed a sensitive quantitative PCR to investigate whether Helicobacter species DNA can be detected in the human gastrointestinal tract. We tested gastric biopsies (including biopsies from H. pylori positive persons), intestinal mucosal biopsies and fecal samples from healthy persons, and intestinal mucosal biopsies from patients with inflammatory bowel disease (IBD) for the presence of Helicobacter species. All gastric biopsies, positive for H. pylori by culture, were also positive in our newly developed PCR. No Helicobacter species were found in the mucosal biopsies from patients with IBD (n = 50) nor from healthy controls (n = 25). All fecal samples were negative. Our study suggests that Helicobacter species, other than H. pylori, are not present in the normal human gastrointestinal flora and our results do not support a role of Helicobacter species in IBD.

Identification of campylobacteria isolated from Danish broilers by phenotypic tests and species-specific PCR assays

AIMS

To validate a phenotypic Campylobacter species identification method employed to identify campylobacters in broilers by comparison with campylobacterial species identification using various species-specific PCR analyses.

METHODS AND RESULTS

From a collection of 2733 phenotypically identified campylobacterial cultures, 108 Campylobacter jejuni cultures and 351 campylobacterial cultures other than Camp. jejuni were subjected to various species-specific PCR assays. On the basis of the genotypic tests, it was demonstrated that Camp. jejuni and Camp. coli constituted approx. 99% of all cultures, while other species identified were Helicobacter pullorum, Camp. lari and Camp. upsaliensis. However, 29% of the 309 Camp. coli cultures identified by phenotypic tests were hippurate-variable or negative Camp. jejuni cultures, whereas some Camp. lari cultures and unspeciated campylobacter cultures belonged to H. pullorum. It was also notable that 2-6% of the cultures were, in fact, mixed cultures.

CONCLUSIONS

The phenotypic identification scheme employed failed to appropriately differentiate Campylobacter species and particularly to identify the closely related species, H. pullorum.

SIGNIFICANCE AND IMPACT OF THE STUDY

Future phenotypic test schemes should be designed to allow a more accurate differentiation of Campylobacter and related species. Preferably, the phenotypic tests should be supplemented with a genotypic strategy to disclose the true campylobacterial species diversity in broilers.

Immune responses to bile-tolerant helicobacter species in patients with chronic liver diseases, a randomized population group, and healthy blood donors

Bile-tolerant Helicobacter species such as Helicobacter pullorum, Helicobacter bilis, and Helicobacter hepaticus are associated with hepatic disorders in animals and may be involved in the pathogenesis of chronic liver diseases (CLD) in humans. Antibody responses to cell surface proteins of H. pullorum, H. bilis, and H. hepaticus in serum samples from patients with CLD, a randomized population group, and healthy blood donors were evaluated by using enzyme linked immunosorbent assay (ELISA). The results were compared with the antibody responses to Helicobacter pylori. For analysis of a possible cross-reactivity between bile-tolerant Helicobacter species and H. pylori, sera from a subpopulation of each group were absorbed with a whole-cell extract of H. pylori and retested by ELISA. Results before absorption showed that the mean value of the ELISA units for H. pullorum was significantly higher in patients with CLD than in healthy blood donors (P = 0.01). Antibody reactivity to cell surface protein of H. hepaticus was also significantly higher in the CLD patients than in the healthy blood donors and the population group (P = 0.005 and P = 0.002, respectively). Following the absorption, antibody responses to H. pullorum decreased significantly in all three groups (P = 0.0001 for CLD patients, P = 0.0005 for the population group, and P < 0.0001 for the blood donors), indicating that cross-reactivity between H. pylori and other Helicobacter spp. occurs. The antibody responses to H. hepaticus and H. bilis in CLD patients remained high following absorption experiments compared to ELISA results before absorption. The significance of this finding requires further investigations.

Review article: Helicobacter species and hepatobiliary diseases

Helicobacter species, which may colonize the biliary tract, have been implicated as a possible cause of hepatobiliary diseases ranging from chronic cholecystitis and primary sclerosing cholangitis to gall-bladder carcinoma and primary hepatic carcinomas. Research in this area has been limited by the lack of a gold standard in the diagnosis of these organisms in bile. Most published data to date have been based on molecular techniques that detect the DNA of Helicobacter species in bile, rather than evidence of viable organisms in bile. Helicobacter species have not been shown to induce histological injury to the biliary epithelium or liver parenchyma. The strongest association of the presence of these organisms in bile is with cholestatic conditions. This article reviews the literature on this newly developing field as it has evolved historically, taking pertinent methodological issues into account.

Bacteremia caused by a Helicobacter pullorum-like organism

We report a case of bacteremia caused by a Helicobacter pullorum-like organism in a 35-year-old man with pyrexia of unknown origin. Culture of blood samples obtained at admission yielded a motile, spiral-shaped gram-negative rod, and 16S rRNA gene sequencing identified this organism as Helicobacter pullorum-like, showing 23 base differences compared with the recently described "Helicobacter canadensis" (a recently proposed group that had previously been classified within H. pullorum). We believe that this is the first report of bacteremia caused by this organism.

Helicobacter winghamensis sp. nov., a novel Helicobacter sp. isolated from patients with gastroenteritis

From 1997 to 1999 seven isolates of Campylobacter-like organisms from five patients that were exhibiting symptoms of gastroenteritis, including fever, stomach malaise, and diarrhea, were investigated. The organisms were isolated from stool samples and found to exhibit a diverse colony morphology; hence multiple isolates were submitted from one of the patients. All isolates were found to be identical. The organisms were catalase, urease, alkaline phosphatase, and nitrate negative but oxidase and indoxyl acetate positive. They grew at 37 degrees C but not at 42 degrees C, and three of the isolates from two different patients were sensitive to nalidixic acid and cephalothin. Full 16S rRNA sequence analysis not only grouped these organisms within the Helicobacter genus but also differentiated them from previously identified Helicobacter species. The closest relative by phylogenetic analysis was Helicobacter sp. flexispira taxon 1. Electron microscopy showed that these isolates had one or two bipolar flagella; however, the periplasmic fibers, a characteristic of the known Helicobacter sp. flexispira taxa, were not observed. The present isolates also lacked a flagellar sheath, a trait shared with four other Helicobacter spp., H. canadensis, H. mesocricetorum, H. pullorum, and H. rodentium. On the basis of the unique phenotypic properties of these isolates and 16S rRNA sequence analysis, we propose the classification of a new Helicobacter species, Helicobacter winghamensis sp. nov.

"Helicobacter rappini" isolates from 2 homosexual men

We report 2 cases of bacteremia due to "Helicobacter rappini" in 2 young, homosexual men, including the first report of H. rappini in a human immunodeficiency virus-positive patient. Blood cultures showed a spiral, fusiform, gram-negative bacterium with bipolar sheathed flagella.

Emergence of diverse Helicobacter species in the pathogenesis of gastric and enterohepatic diseases

Since Helicobacter pylori was first cultivated from human gastric biopsy specimens in 1982, it has become apparent that many related species can often be found colonizing the mucosal surfaces of humans and other animals. These other Helicobacter species can be broadly grouped according to whether they colonize the gastric or enterohepatic niche. Gastric Helicobacter species are widely distributed in mammalian hosts and are often nearly universally prevalent. In many cases they cause an inflammatory response resembling that seen with H. pylori in humans. Although usually not pathogenic in their natural host, these organisms serve as models of human disease. Enterohepatic Helicobacter species are an equally diverse group of organisms that have been identified in the intestinal tract and the liver of humans, other mammals, and birds. In many cases they have been linked with inflammation or malignant transformation in immunocompetent hosts and with more severe clinical disease in immunocompromised humans and animals. The purpose of this review is to describe these other Helicobacter species, characterize their role in the pathogenesis of gastrointestinal and enterohepatic disease, and discuss their implications for our understanding of H. pylori infection in humans.

A probable new Helicobacter species isolated from a patient with bacteremia

A probable new Helicobacter species was isolated from the blood of a 14-month-old aboriginal child who presented with vomiting, diarrhea, fever, and dry cough. The most similar 16S rRNA gene sequence was that of Helicobacter fennelliae CCUG 18820(T) but the new sequence differed from it by at least 32 base substitutions and by the presence of a large (353-nucleotide) intervening sequence.

Differentiation of clinical Helicobacter pullorum isolates from related Helicobacter and Campylobacter species

BACKGROUND

Helicobacter pullorum, first detected in the liver and intestinal contents of poultry, was defined as a new species in 1994. This organism has since been isolated from humans with gastroenteritis. Phenotypic as well as genotypic methods have been used to identify H. pullorum associated with cases of human disease.

MATERIALS AND METHODS

Clinical isolates were submitted for identification to the National Laboratory for Enteric Pathogens by Provincial Public Health Laboratories within Canada. Phenotypic characterization was conducted using a variety of growth and biochemical tests including oxidase, catalase, indoxyl acetate, H2S production in triple sugar iron (TSI) agar, antimicrobial susceptibility testing, and fatty acid analysis. Genotypic identification was performed using a polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) analysis of a 1-kb fragment of the Helicobacter 16S rRNA gene.

RESULTS

During the last 7 years (1993-1999) a total of 11 isolates of H. pullorum were detected from patients with gastroenteritis for inclusion in this study. Typically, these isolates were oxidase and catalase positive, produced optimal growth at 42 degrees C, and produced H2S in TSI. Of these 11 isolates, 1 showed DNase activity, while another did not produce H2S in TSI, and only 2 showed tolerance to 1% bile. Antimicrobial susceptibility assays indicated that 6 of the 11 strains were resistant to nalidixic acid. The fatty acid profiles of the isolates were similar to each other and provided a distinguishing profile from the other related species. Genetically identical and distinct species-specific restriction fragment-length polymorphism (RFLP) patterns were produced using the restriction enzymes Bsr I and Dde I.

CONCLUSION

Phenotypic and genotypic procedures were used to identify H. pullorum. Interspecies phenotypic variability was apparent and supported the use of a polyphasic approach for identification. Similarities to the more prominent human pathogens Campylobacter coli and C. lari were also noted. The use of a combination of phenotypic and, in particular, genotypic markers for H. pullorum should prove valuable both for epidemiological investigations and for the diagnosis of disease related to this emerging human pathogen.

Cytolethal distending toxin sequence and activity in the enterohepatic pathogen Helicobacter hepaticus

Little is known about the molecular pathogenesis of hepatitis and enterocolitis caused by enterohepatic Helicobacter species. Sonicates of the murine pathogen Helicobacter hepaticus were found to cause progressive cell distension, accumulation of filamentous actin, and G(2)/M cell cycle arrest in HeLa cell monolayers. The genes encoding this cytotoxic activity were cloned from H. hepaticus. Three open reading frames with closest homology to cdtA, cdtB, and cdtC from Campylobacter jejuni were identified. Sonicates of a laboratory strain of Escherichia coli carrying the cloned cdtABC gene cluster from H. hepaticus reproduced the cytotoxic activities seen with sonicates of H. hepaticus. Cytolethal distending toxin activity is a potential virulence determinant of H. hepaticus that may play a role in the pathogenesis of Helicobacter-associated hepatitis and enterocolitis.

Colonization and tissue tropism of Helicobacter pylori and a novel urease-negative Helicobacter species in ICR mice are independent of route of exposure

BACKGROUND

In humans, Helicobacter pylori is known to colonize the stomach and to induce persistent gastritis; selected reports also suggest it causes extragastric disease, including hepatitis. H. pylori and a novel urease-negative Helicobacter sp. induce gastritis and typhlocolitis, respectively, when inoculated orally into mice. Experimental typhlocolitis and hepatitis have been caused by intraperitoneal (i.p.) injection of H. hepaticus, H. bilis, and the novel Helicobacter spp. However, the route by which i.p.-inoculated organisms localize to specific areas of the gastrointestinal system is unknown.

MATERIALS AND METHODS

To determine whether Helicobacter spp. can be isolated from blood, can preferentially colonize specific tissues, and can cause pathological changes, we inoculated 6-week-old outbred mice orally or intraperitoneally with H. pylori or a novel Helicobacter sp.

RESULTS

When these mice were inoculated by the i.p. route, H. pylori was cultured from lungs, spleen, liver, cecum, and stomach on day 1 after inoculation, from liver and stomach mucosa on day 3 after inoculation, and from the stomach on day 30 after inoculation, suggesting preferential colonization of the stomach. After inoculation by the i.p. route, the novel intestinal Helicobacter sp. was cultured from the blood, lungs, spleen, liver, kidneys, cecum, and feces but not from stomach mucosa on day 1 after inoculation. By day 30 after inoculation, the novel Helicobacter sp. was cultured from cecum and feces only, suggesting that it had preferentially colonized the lower bowel. By the i.p. route, the novel Helicobacter sp. induced hepatitis that persisted for 30 days after inoculation. Though mice inoculated intraperitoneally with H. pylori developed an acute hepatitis, the liver lesion began to resolve 30 days after inoculation. Mice inoculated orally with either H. pylori or the novel Helicobacter sp. did not have hepatitis on day 30 after inoculation but developed 100% colonization of stomach and cecum, respectively.

CONCLUSION

The isolation of H. pylori and the novel Helicobacter sp. from multiple tissues infers that a transient helicobacter bacteremia occurs when Helicobacter spp. are injected intraperitoneally, but organisms are cleared rapidly from nontarget tissues and preferentially colonize specific regions of the gastrointestinal tract.