Helicobacter pylori : Clonal Population Structure and Restricted Transmission within Families Revealed by Molecular Typing

Abstract

Helicobacter pylori infects up to 50% of the human population worldwide. The infection occurs predominantly in childhood and persists for decades or a lifetime. H. pylori is believed to be transmitted from person to person. However, tremendous genetic diversity has been reported for these bacteria. In order to gain insight into the epidemiological basis of this phenomenon, we performed molecular typing of H. pylori isolates from different families. Fifty-nine H. pylori isolates from 27 members of nine families were characterized by using restriction fragment length polymorphism analysis of five PCR-amplified genes, by pulsed-field gel electrophoresis (PFGE) of chromosomal DNA, and byvacA and cagA genotyping. The 16S rRNA gene exhibited little allelic variation, as expected for a unique bacterial species. In contrast, the vacA, flaA,ureAB, and lspA-glmM genes were highly polymorphic, with a mean genetic diversity of 0.83, which exceeds the levels recorded for all other bacterial species. In conjunction with PFGE, 59 H. pylori isolates could be differentiated into 21 clonal types. Each individual harbored only one clone, occasionally with a clonal variant. Identical strains were always found either between siblings or between a mother and her children. Statistical analysis revealed clonality of population structure in all isolates. The results of this study suggest the possible coexistence of a large array of clonal lineages that are evolving in each individual in isolation from one another. Transmission appears to occur primarily from mother to child and perhaps between siblings.

Long‐term follow‐up of Helicobacter pylori eradication therapy in Vietnam: reinfection and clinical outcome

“…Reinfection with the same strain has been suggested to indicate recrudescence of the same infection but could also be due to reinfection with the same strain from an infected individual in the environment of the patient. Conflicting results have been reported on the possibility of transmission of identical H. pylori strains among family members 34–36 . In a previous fingerprinting study, we have found a high degree of concordance of H. pylori strains within families 31 .…”

Does hospital work constitute a risk factor for Helicobacter pylori infection?

“…Person-to-person spread therefore seems to be the most likely mode of transmission. 2 Evidence that supports person-to-person transmission includes the clustering of H. pylori infection in families, [6][7][8] in institutions for the mentally handicapped 9,10 and in submarine crews. 11 As well as in the human stomach, viable H. pylori cells have been detected in faeces and oral secretions.…”

Helicobacter pylorienter and survive within multivesicular vacuoles of epithelial cells

“…Helicobacter pylori colonize the gastric mucosa of about 50% of human beings throughout the world. Infection usually occurs in childhood and can persist for a lifetime (Neale and Logan, 1995;Rothenbacher et al ., 1999;Goodman and Correa, 2000;Han et al, 2000;Miyaji et al, 2000). Chronic asymptomatic gastritis is the most common outcome of infection, but some individuals also develop peptic and duodenal ulcers and 1% of infected individuals will develop gastric cancer.…”