Association of Helicobacter bilis Infection with the Development of Colorectal Cancer

The first two human infections with Helicobacter zhangjianzhongii, a new Helicobacter closely related to Helicobacter canis

PURPOSE

In 2023, Helicobacter zhangjianzhongii was proposed as a new species in the Helicobacter genus. We here describe two human cases of H. zhangjianzhongii bacteremia.

METHODS

Four clinical strains from the Helicobacter genus isolated from blood culture between 2017 and 2023 were studied. They were initially identified as H. canis by MALDI-TOF and 16S rDNA sequencing. The strains were biochemically characterized and tested at different temperatures and atmospheres. Two databases were used to characterize the isolates: the Bruker® MBT compass Version 4.1.1 database and a in-house spectrum-enriched database. After bacterial DNA extraction the genomes were sequenced on NovaSeq 6000 (Illumina) and analyzed using an in-house pipeline.

RESULTS

Case 1 involved a 58-year-old woman who was hospitalized in a thoracic oncology unit because her general condition deteriorated in a setting of small-cell carcinoma. She presented with abdominal pain associated with significant hepatomegaly. Case 2 involved a 78-year-old woman on rituximab who was hospitalized to treat chest pain, anemia, and inflammatory syndrome. Both strains exhibited very similar microbiological and genomic characteristics, thus growth in a microaerobic atmosphere at 37°C and 42°C, oxidase-positivity, and urease- and catalase-negativity. Both were formally identified by whole-genome sequencing as H. zhangjianzhongii (ANI > 99% and DDH > 94%).

CONCLUSION

This proposed species is associated with bacteremia in humans. It is thus likely to be a novel human pathogen. Dogs may have been the source of infection.

Helicobacter cholecystus Bacteremia in an Adult with Acute Cholecystitis

We report the isolation of Helicobacter cholecystus from a positive blood culture of a 58-year-old male with bacteremia and acute cholecystitis, in China. The patient's condition improved after symptomatic support treatment and subtotal cholecystectomy. This suggests that H. cholecystus should be considered a potential human pathogen.

Helicobacter bilis Contributes to the Occurrence of Inflammatory Bowel Disease by Inducing Host Immune Disorders

Gut microbiota coevolve with humans to achieve a symbiotic relationship, which ultimately leads to physiological homeostasis. A variety of diseases can occur once this balance is disrupted. Helicobacter bilis (H. bilis) is an opportunistic pathogen in humans, triggering multiple diseases, including inflammatory bowel disease (IBD). IBD is a chronic immunologically mediated inflammation of the human gastrointestinal tract, and its occurrence is closely related to the gut microbiota. Several studies have demonstrated that H. bilis colonization is associated with IBD, and its mechanism is related to host immunity. However, few studies have investigated these mechanisms of action. Therefore, this article is aimed at reviewing these studies and summarizing the mechanisms of H. bilis-induced IBD from two perspectives: adaptive immunity and innate immunity. Furthermore, this study provides a preliminary discussion on treating H. bilis-related IBD. In addition, we also demonstrated that H. bilis played an important role in promoting the carcinogenesis of IBD and discussed its mechanism.

Prevalence, diversity and public health implications of Helicobacter species in pet and stray dogs

Background

It is probable that humans can acquire H. pylori and non—H. pylori Helicobacter infections via domestic animals. The prevalence and risk factors of infections of Helicobacter species in canines of Taipei city were therefore analysed in this study.

Materials and methods

A total of 95 canine faecal samples were collected from different animal shelters and hospitals in Taipei city. Total DNA was extracted for semi-nested PCR detection of Helicobacter species. The PCR products were sequenced for further comparative database and phylogenetic analyses.

Results

The overall prevalence of Helicobacter species in canines of Taipei city was 75.79% (72/95). Two gastric, seven enterohepatic and two unclassified Helicobacter species were identified, all of which have been implicated in the aetiology of human diseases. The predominant species detected included H. canis (27.78%), H. pylori (26.39%), H. canicola (18.06%), and H. bilis (13.89%) in decreasing order, while H. canadensis and H. typhlonius were identified for the first time in canines. The genotypes in H. pylori and H. canicola clusters grouped together, with their respective reference strains, showed a close evolutionary distance in the phylogenetic tree, indicating a common ancestry may have existed in these clusters respectively. The residential region of canines, dog living status (pet or stray) and breed (purebred or mixed-breed) are the risk factors associated with Helicobacter infections in the canines examined.

Conclusion

The high prevalence of Helicobacter infections in canines highlights a potential public health risk of zoonotic transmission among dogs, humans and other animals, and therefore, the need for proper methods in controlling the transmission routes. In addition, the 16S rRNA gene amplification method was found to be useful for bacterial identification and phylogenetic analysis.

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The prevalence of Helicobacter infection in dogs of Taipei city was found to be 75.79%.

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Species detected included H. canis, H. pylori, H. canicola, H. bilis and others, including 2 unclassified species.

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Almost all the species detected are identical with those reported to be found in humans in some other studies, suggesting possible cross-transmission between humans and canines.

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Residential region, living status (pet or stray) and breed type of canines are risk factors associated with Helicobacter infections in the canines.

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Phylogenetic analysis indicated an evolutionary pattern in H. pylori and H. canicola clusters, suggesting a common ancestry may have existed in these clusters respectively.