Effect of Small Bowel Bacterial Overgrowth on the Immunogenicity of Single‐Dose Live Oral Cholera Vaccine CVD 103‐HgR

TLDR

Live oral vaccines, including CVD 103‑HgR, elicit weaker immune responses in developing countries compared to industrialized settings. The study tested whether proximal small bowel bacterial overgrowth reduces the vibriocidal antibody response to the single‑dose live oral cholera vaccine CVD 103‑HgR. Researchers performed lactulose breath H₂ tests on 202 fasting 5‑ to 9‑year‑old Santiago schoolchildren one day before administering CVD 103‑HgR to detect proximal small bowel bacterial overgrowth. Of 178 analyzable children, 10 (5.6%) had small bowel overgrowth; seroconversion rates were similar (60% vs 67%) but geometric mean titers were lower (160 vs 368), and higher peak breath H₂ and greater weight were associated with reduced seroconversion.

Abstract

Several live oral vaccines (polio, bovine rotavirus, CVD 103-HgR cholera) are less immunogenic in developing than in industrialized countries. It was hypothesized that proximal small bowel bacterial overgrowth (common in children in less developed countries but rare in industrialized settings) diminishes the vibriocidal antibody response to CVD 103-HgR. In total, 202 fasting Santiago schoolchildren aged 5–9 years had lactulose breath H2 tests to detect proximal small bowel bacteria 1 day before ingesting CVD 103-HgR. Florig small bowel overgrowth was observed in 10 (5.6%) of 178 analyzable children. In children with florid overgrowth, vibriocidal seroconversion differed little from other children (60% vs. 67%), but the geometric mean titer was lower (160 vs. 368; P = .25). By logistic regression, increased peak breath H2 at small bowel time points was associated with diminished seroconversion (P = .04), as was the interaction of H2 value and weight (children >25 kg had lower seroconversion rates among subjects with heaviest overgrowth).