Helicobacter pylori infection: further evidence for the role of feco-oral transmission

Gastrointestinal symptoms of long COVID-19 related to the ectopic colonization of specific bacteria that move between the upper and lower alimentary tract and alterations in serum metabolites

BACKGROUND

Since the coronavirus disease 2019 (COVID-19) outbreak, many COVID-19 variants have emerged, causing several waves of pandemics and many infections. Long COVID-19, or long-term sequelae after recovery from COVID-19, has aroused worldwide concern because it reduces patient quality of life after rehabilitation. We aimed to characterize the functional differential profile of the oral and gut microbiomes and serum metabolites in patients with gastrointestinal symptoms associated with long COVID-19.

METHODS

We prospectively collected oral, fecal, and serum samples from 983 antibiotic-naïve patients with mild COVID-19 and performed a 3-month follow-up postdischarge. Forty-five fecal and saliva samples, and 25 paired serum samples were collected from patients with gastrointestinal symptoms of long COVID-19 at follow-up and from healthy controls, respectively. Eight fecal and saliva samples were collected without gastrointestinal symptoms of long COVID-19 at follow-up. Shotgun metagenomic sequencing of fecal samples and 2bRAD-M sequencing of saliva samples were performed on these paired samples. Two published COVID-19 gut microbiota cohorts were analyzed for comparison. Paired serum samples were analyzed using widely targeted metabolomics.

RESULTS

Mild COVID-19 patients without gastrointestinal symptoms of long COVID-19 showed little difference in the gut and oral microbiota during hospitalization and at follow-up from healthy controls. The baseline and 3-month samples collected from patients with gastrointestinal symptoms associated with long COVID-19 showed significant differences, and ectopic colonization of the oral cavity by gut microbes including 27 common differentially abundant genera in the Proteobacteria phylum, was observed at the 3-month timepoint. Some of these bacteria, including Neisseria, Lautropia, and Agrobacterium, were highly related to differentially expressed serum metabolites with potential toxicity, such as 4-chlorophenylacetic acid, 5-sulfoxymethylfurfural, and estradiol valerate.

CONCLUSIONS

Our study characterized the changes in and correlations between the oral and gut microbiomes and serum metabolites in patients with gastrointestinal symptoms associated with long COVID-19. Additionally, our findings reveal that ectopically colonized bacteria from the gut to the oral cavity could exist in long COVID-19 patients with gastrointestinal symptoms, with a strong correlation to some potential harmful metabolites in serum.

Oral-Gut Microbiome Axis in Gastrointestinal Disease and Cancer

It is well-known that microbiota dysbiosis is closely associated with numerous diseases in the human body. The oral cavity and gut are the two largest microbial habitats, playing a major role in microbiome-associated diseases. Even though the oral cavity and gut are continuous regions connected through the gastrointestinal tract, the oral and gut microbiome profiles are well-segregated due to the oral-gut barrier. However, the oral microbiota can translocate to the intestinal mucosa in conditions of the oral-gut barrier dysfunction. Inversely, the gut-to-oral microbial transmission occurs as well in inter- and intrapersonal manners. Recently, it has been reported that oral and gut microbiomes interdependently regulate physiological functions and pathological processes. Oral-to-gut and gut-to-oral microbial transmissions can shape and/or reshape the microbial ecosystem in both habitats, eventually modulating pathogenesis of disease. However, the oral-gut microbial interaction in pathogenesis has been underappreciated to date. Here, we will highlight the oral-gut microbiome crosstalk and its implications in the pathogenesis of the gastrointestinal disease and cancer. Better understanding the role of the oral-gut microbiome axis in pathogenesis will be advantageous for precise diagnosis/prognosis and effective treatment.

Oral–Gut Microbiome Axis in Gastrointestinal Disease and Cancer

It is well-known that microbiota dysbiosis is closely associated with numerous diseases in the human body. The oral cavity and gut are the two largest microbial habitats, playing a major role in microbiome-associated diseases. Even though the oral cavity and gut are continuous regions connected through the gastrointestinal tract, the oral and gut microbiome profiles are well-segregated due to the oral–gut barrier. However, the oral microbiota can translocate to the intestinal mucosa in conditions of the oral–gut barrier dysfunction. Inversely, the gut-to-oral microbial transmission occurs as well in inter- and intrapersonal manners. Recently, it has been reported that oral and gut microbiomes interdependently regulate physiological functions and pathological processes. Oral-to-gut and gut-to-oral microbial transmissions can shape and/or reshape the microbial ecosystem in both habitats, eventually modulating pathogenesis of disease. However, the oral–gut microbial interaction in pathogenesis has been underappreciated to date. Here, we will highlight the oral–gut microbiome crosstalk and its implications in the pathogenesis of the gastrointestinal disease and cancer. Better understanding the role of the oral–gut microbiome axis in pathogenesis will be advantageous for precise diagnosis/prognosis and effective treatment.

Characteristics of Helicobacter pylori-seropositive subjects according to the stool antigen test findings: a prospective study

BACKGROUND/AIMS

In countries with a higher risk of gastric atrophic gastritis, noninvasive tests are helpful for a more reliable diagnosis of Helicobacter pylori infection. The aim of this study was to evaluate the characteristics of seropositive subjects according to their stool H. pylori antigen test, serum pepsinogen (PG) assay, and endoscopic findings.

METHODS

Consecutive subjects who visited Konkuk University Medical Center for upper gastrointestinal endoscopy for a regular check-up were included in a prospective setting if the serum anti-H. pylori immunoglobulin G assay was positive. A H. pylori antigen stool test was measured using a stool H. pylori antigen enzyme-linked immunosorbent assay kit on the same day as a serum PG assay and endoscopy.

RESULTS

Of 318 seropositive subjects, 256 (80.5%) showed positive stool test findings. Subjects with a negative stool test result showed lower serum PG I (p < 0.001) and PG II (p < 0.001) levels and higher PG I/II ratio (p < 0.001) than those with a positive stool test. Chronic atrophic gastritis was more common in the positive stool test group than the negative stool test group on endoscopic finding (p = 0.009). A higher serum PG I level (p = 0.001) and a lower serum PG I/II ratio (p = 0.001) were independent risk factors for the presence of H. pylori antigen in stool.

CONCLUSION

A high serum PG level denotes an ongoing current H. pylori infection with positive stool H. pylori antigen test findings. Seropositive subjects with increased gastric secreting ability tend to have H. pylori in their fecal material as reflected by a positive stool H. pylori antigen test finding.

Serologic Evidence for Fecal-Oral Transmission of Helicobacter pylori

Helicobacter pylori infection is among the most prevalent infections in the world and a key cause of gastric diseases; however, its route of transmission remains unclear. This study aimed to assess the potential for fecal-oral transmission of H. pylori by leveraging its association with a disease with known etiology. Utilizing serology data from the National Health and Nutrition Examination Survey (NHANES 1999; N = 6,347), the association between H. pylori and hepatitis A virus (HAV), a sensitive indicator for fecal-oral exposure, was assessed. Survey-weighted kappa and multiple logistic regression were used to quantify the association between H. pylori and HAV after controlling for age, sex, race, poverty, birthplace, crowding, smoking, and alcohol use. Concordant serological results were found among 69.8% of participants (survey-weighted κ = 0.30, 95% confidence interval [CI] = 0.26, 0.35). The adjusted odds of H. pylori seropositivity were over two times higher after adjusting for confounders (odds ratio = 2.27, 95% CI = 1.79, 2.87). Results from this study suggest H. pylori and HAV infections are strongly associated. Since HAV is primarily transmitted through the fecal-oral route, fecal-oral transmission may be an important pathway for H. pylori spread.

Survey of Helicobacter infection in domestic and feral cats in Korea

Discovery of Helicobacter (H.) pylori has led to a fundamental change in our understanding of gastric diseases in humans. Previous studies have found various Helicobacter spp. in dogs and cats, and pets have been questioned as a zoonotic carrier. The present study surveyed the Helicobacter infections and investigated the presence of H. felis and H. pylori infections in domestic and feral cats in Korea. Sixty-four domestic cats and 101 feral cats were selected from an animal shelter. Saliva and feces were evaluated by Helicobacter genus-specific polymerase chain reaction (PCR). Genus-specific PCR positive samples were further evaluated for H. felis and H. pylori using specific primer pairs. Thirty-six of 64 (56.3%) samples from domestic cats and 92 of 101 (91.1%) samples from feral cats were PCR positive; the positive rate of feces samples was higher than that of saliva samples in both groups. H. felis and H. pylori species-specific PCR was uniformly negative. The prevalence of Helicobacter spp. in feral cats was approximately two-fold higher than that of domestic cats. The fecal-oral route may be more a common transmission route not only between cats but also in humans.

The seroepidemiology of Helicobacter pylori infection in Australia

BACKGROUND

Infection with Helicobacter pylori is common worldwide and a significant cause of upper gastrointestinal disease. Prevalence of this infection varies in different population groups internationally. Because of the invasiveness of specimen collection for bacteriologic diagnosis and the expense of tests such as labeled urea breath tests, serology is the most feasible means of determining the population epidemiology of H. pylori. The aim of this study was to describe the seroepidemiology of H. pylori infection in Australia.

METHODS

H. pylori-specific ELISA for the presence of IgG antibodies was performed on a representative sample of 2413 sera from Australia in 2002, using validated serosurveillance methods.

RESULTS

The overall seroprevalence of H. pylori infection in Australia was 15.1% in 2002, with no statistical difference between genders. Seropositivity rates increased progressively with age, ranging between 4.0% in the 1-4-year-olds and 23.3% in the 50-59-year-olds.

CONCLUSIONS

The prevalence of infection with H. pylori in Australia was lower than rates reported in other developed countries, at 15.4%. This study provides important baseline measurements for future preventive measures including vaccine research and development. Further studies to determine subgroups at higher risk of infection may help target the more susceptible populations.

H pylori: Treatment for the patient only or the whole family?

AIM: To compare the effects of treatment of H pylori-infected individuals with the effects of treatment of individuals as well as all H pylori-infected family members.

METHODS: H pylori-positive patients with similar demographic specifications were prospectively randomized with respect to treatment, with a triple regimen of either patients and all H pylori-positive family members living together (groupI) or patients only (group II). Nine months after treatment, all patients were assessed for H pylori positivity.

RESULTS: There were 70 H pylori-positive patients in each group; patients in groupsIand II lived with 175 and 190 H pylori-positive relatives, respectively. Age, sex and H pylori positivity rate were similar in both groups of relatives. Nine months after 14 d standard triple therapy, H pylori positivity was 7.1% in groupIpatients and 38.6% in group II patients [P < 0.01, OR = 8.61 95% confidence interval (CI): 2.91-22.84].

CONCLUSION: The present results indicate bad environmental hygienic conditions and close intra-familial relationships are important in H pylori contamination. These findings indicate all family members of H pylori-positive individuals should be assessed for H pylori positivity, particularly in developing countries where H pylori prevalence is high; they also suggest patients, their spouses and all H pylori-positive family members of H pylori-positive individuals should be treated for H pylori infection.

Epidemiology of Helicobacter pylori infection

Helicobacter pylori infection is typically acquired in early childhood in both low- and high-income regions of the world and, once established, commonly persists lifelong unless treated. Social and economic development decreases the prevalence both within and between countries. The epidemiology of H. pylori infection highlights the geographic, ethnic, and racial differences throughout the world.