Pre-existing Helicobacter pylori serum IgG enhances the vibriocidal antibody response to CVD 103-HgR live oral cholera vaccine in Malian adults

Mucosal and systemic immune responses to Vibrio cholerae infection and oral cholera vaccines (OCVs) in humans: a systematic review

INTRODUCTION

Cholera is an enteric disease caused by Vibrio cholerae, a water-borne pathogen, and characterized by severe diarrhea. Vaccines have been recommended for use by the WHO in resource-limited settings. Efficacies of the currently licensed cholera vaccines are not optimal in endemic settings and low in children below the age of five, a section of the population most susceptible to the disease. Development of next generation of cholera vaccines would require a detailed understanding of the required protective immune responses.

AREA COVERED

In this review, we revisit clinical trials which are focused on the early transcriptional mucosal responses elicited during Vibrio cholerae infection and upon vaccination along with summarizing various components of the effector immune response against Vibrio cholerae.

EXPERT OPINION

The inability of currently licensed killed/inactivated vaccines to elicit key inflammatory pathways locally may explain their restricted efficacy in endemic settings. More studies are required to understand the immunogenicity of the live attenuated cholera vaccine in these regions. Various extrinsic and intrinsic factors influence anti-cholera immunity and need to be considered to develop region-specific next generation vaccines.

Evaluation of antibiotic resistance of Helicobacter pylori bacteria obtained from gastric biopsy samples: A cohort study

Objective

Helicobacter pylori infection is associated with a wide range of gastrointestinal diseases and is very common in developing countries. Overuse and self-prescribed antibiotics have led to antibiotic resistance and failure of complete eradication of the bacterium. The aim of this study is to evaluate the antibiotic resistance of h. pylori from samples obtained from gastric biopsy.

Methods

In this descriptive-analytical study was performed on 205 patients’ samples positive for h. pylori infection. Following h. pylori testing, the sample were culture with different antibiotics to obtain data regarding the resistance. Demographic information of the patients such as age, sex, employment status, area of residence and patient-related factors such as reason for referral, and previous history of treatment were obtained and evaluated for the correlation with antibiotic resistance.

Results

In this study, the mean age of the subjects was 42.32 ± 16.65 years. The most common reason for referral of patients in the present study was epigastric pain in 49.3% (101 patients). Antibiotic resistance to amoxicillin was 46.8%, tetracycline was 41%, metronidazole was 33.2%, clarithromycin was 70.7%. levofloxacin was 36.1% and bismuth was 19.5%. Sex, age, type of living (rural or urban), employment, reason for referral and history of treatment was not associated with any antibiotic resistance, p > 0.05.

Conclusion

Our study showed that clarithromycin resistance is the most common in our population followed by amoxicillin and tetracycline. Excessive use of these antibiotics and self-prescription should be analyzed in future studies and public-awareness programs might be required.

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H.pylori infection is associated with a wide range of gastrointestinal diseases.

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Self-prescribed antibiotics have led to antibiotic resistance and failure of complete eradication.

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Clarithromycin resistance is the most common in our population followed by amoxicillin and tetracycline.

Relationship Between Helicobacter pylori IgG Seroprevalence and the Immune Response to Poliovirus Vaccine Among School-Age Children From a Population With Near-Universal Immunity Level

Objectives

To examine the association between Helicobacter pylori seroprevalence and serum pepsinogens (PGs) as markers of gastric inflammation), with high neutralizing antibody titers to poliovirus type 1 and 3 vaccine strains among children age 3–4 years, subsequent to sub-clinical infection acquired during a wild-type poliovirus type 1 outbreak in Israel.

Methods

A serosurvey was conducted among 336 children aged 5–17 years who were vaccinated with both inactivated polio vaccine and oral polio vaccines. H. pylori serum IgG antibodies and PG concentrations were measured using ELISA. Neutralizing antibodies to poliovirus vaccine strains were measured and children with a titer ≥1:8 were considered immune. High-level immunity was defined as having a serum NA titer >1:2048. Propensity score inverse weighting was used to account for confounders.

Results

Neutralizing antibodies titers ≥1:8 to poliovirus type 1 and 3 vaccine strains were found in 99.4 and 98.2% of the children, respectively. An inverse association was found between H. pylori seropositivity accompanied by PGI:PGII ratio ≤6.5 (marker of gastric inflammation) and high-level immunity to poliovirus type 1: OR 0.39 (95% CI 0.68–0.91), p = 0.027. The association between H. pylori seropositivity of CagA virulent phenotype and polio high immunity was not significant. The association between H. pylori seropositivity and high neutralizing antibodies to type 3 poliovirus was of low magnitude and not significant.

Conclusions

H. pylori seroprevalence accompanied by evidence of gastric inflammation was inversely correlated with high titers of neutralizing antibodies to poliovirus in children from a population with near universal polio immunity.

Update on CVD 103-HgR single-dose, live oral cholera vaccine

Cholera remains endemic in >50 countries, putting millions at risk, especially young children for whom killed vaccines offer limited protection. An oral, live attenuated vaccine - CVD 103-HgR (Vaxchora vaccine) - was licensed by the US FDA in 2016 for adults aged 18-64 years traveling to endemic regions, based on clinical trials in human volunteers showing the vaccine was well tolerated and conferred 90% efficacy within 10 days. The evidence base for Vaxchora vaccine has expanded with additional clinical trial data, in older adults (aged 46-64 years) and children (aged 2-17 years), demonstrating that the vaccine produces a strong vibriocidal antibody response. Over 68,000 doses have been administered in the United States, with no new safety signals. The dose volume has been reduced in children to improve acceptability, and cold chain requirements are less st ringent, at +2°C─+8°C. The vaccine has recently been licensed in the Untied States for children aged 2-17 years, in Europe for individuals aged ≥2 years, and for home administration in Europe. Next steps include a Phase 4 study in infants (6-23 months). Additional information is needed regarding duration of immunity, the need for and timing of revaccination, and efficacy data from lower-middle-income countries.