High prevalence of mixed infections by <i>Helicobacter pylori</i> in Hong Kong: metronidazole sensitivity and overall genotype

Wong, Bcy; Wang, W. H.; Berg, Douglas E.; Fung, F. M. Y.; Wong, K. W.; Wong, Wai Man; Lai, K. C.; Cho, C. H.; Hui, W. M.; Lam, Shiu‐Kum

doi:10.1046/j.1365-2036.2001.00949.x

Cited by 44 publications

(37 citation statements)

References 32 publications

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“…Further, it is possible to underestimate familial clustering by not investigating all strains that may theoretically infect an individual (40). In the presence of both shared and unique isolates, the number of shared strains will be underestimated if only the unique ones are examined.…”

Section: Discussionmentioning

confidence: 99%

Concordance ofHelicobacter pyloriStrains within Families

et al. 2003

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Helicobacter pylori infection is typically acquired in early childhood, and a predominantly intrafamilial transmission has been postulated. To what extent family members share the same strains is poorly documented. Our aim was to explore patterns of shared strains within families by using molecular typing. Family members of H. pylori-infected 10-to 12-year-old index children identified in a school survey were invited to undergo gastroscopy. Bacterial isolates were typed with random amplified polymorphic DNA and PCRrestriction fragment length polymorphism of the genes ureA-B, glmM, or flaA. The presence or absence of the cag pathogenicity island, a bacterial virulence factor, was determined by PCR. GelCompar II software, supplemented with visual inspection, was used in the cluster analysis. In 39 families, 104 individuals contributed 208 bacterial isolates from the antrum and corpus. A large proportion, 29 of 36 (81%) of the offspring in a sibship, harbored the same strain as at least one sibling. Mother-offspring strain concordance was detected in 10 of 18 (56%) of the families. Of 17 investigated father-offspring relations in eight families, none were strain concordant. Spouses were infected with the same strains in 5 of 23 (22%) of the couples. Different strains in the antrum and corpus were found in 8 of 104 (8%) of the subjects. Our family-based fingerprinting study demonstrates a high proportion of shared strains among siblings. Transmission between spouses seems to be appreciable. The data support mother-child and sib-sib transmission as the primary transmission pathways of H. pylori.Helicobacter pylori colonizes half of the world's population, and the infection is associated with chronic gastritis, peptic ulcer, gastric cancer, and gastric lymphoma. In-depth knowledge of the transmission patterns may constitute important information for future intervention strategies.In the absence of consistent and verified environmental reservoirs, a predominantly person-to-person transmission has been postulated. H. pylori infection is associated with poor living conditions, and possible transmission routes are fecaloral, oral-oral, or gastro-oral, but firm evidence is lacking (36). The infection clusters in families and is usually acquired in early childhood. A child's risk of being infected is largely determined by the presence or absence of infected family members. Having an infected mother has been suggested to be a more prominent risk factor than having an infected father (30,35). Indications of sib-sib transmission have been reported (14). Transmission between spouses occurs but its significance is unclear (5, 9, 19).Molecular typing of pathogens can corroborate and further characterize the transmission pathways suggested by epidemiologic data based on infection status. Shared strains among individuals indicate person-to-person transmission or acquisition from a common source. Unrelated individuals harbor distinct H. pylori isolates (1), while clonal lineages can be discerned within families (2,7,11,16,20,22,24,2...

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Section: Discussionmentioning

confidence: 99%

Concordance ofHelicobacter pyloriStrains within Families

et al. 2003

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“…A smaller number of patients (10 to 20%) have shown evidence of a mixed infection, defined as clones from a single patient that are more similar to isolates from other patients than they are to each other. Interestingly, strains isolated at the same time or after 6 months to 10 years have shown similar divergence (11,35,40,41,46,57). Thus, while populations may diverge within the host, divergence appears to occur slowly.…”

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confidence: 88%

“…Molecular fingerprinting studies using RAPD (57), amplified fragment length polymorphisms (AFLP) (40), and sequence analysis of virulence-associated or housekeeping genes (20,46) with multiple single-colony isolates or cultures obtained from separate biopsy samples from single patients revealed that strains isolated from single patients were closely related but that there were subtle differences in the majority of patients. The variants have even been referred to as quasispecies of a single strain (35).…”

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confidence: 99%

Genetic Analysis of Helicobacter pylori Strain Populations Colonizing the Stomach at Different Times Postinfection

et al. 2007

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Genetic diversity of the human gastric pathogen Helicobacter pylori in an individual host has been observed; whether this diversity represents diversification of a founding strain or a mixed infection with distinct strain populations is not clear. To examine this issue, we analyzed multiple single-colony isolates from two to four separate stomach biopsies of eight adult and four pediatric patients from a high-incidence Mexican population. Eleven of the 12 patients contained isolates with identical random amplified polymorphic DNA, amplified fragment length polymorphism, and vacA allele molecular footprints, whereas a single adult patient had two distinct profiles. Comparative genomic hybridization using whole-genome microarrays (array CGH) revealed variation in 24 to 67 genes in isolates from patients with similar molecular footprints. The one patient with distinct profiles contained two strain populations differing at 113 gene loci, including the cag pathogenicity island virulence genes. The two strain populations in this single host had different spatial distributions in the stomach and exhibited very limited genetic exchange. The total genetic divergence and pairwise genetic divergence between isolates from adults and isolates from children were not statistically different. We also analyzed isolates obtained 15 and 90 days after experimental infection of humans and found no evidence of genetic divergence, indicating that transmission to a new host does not induce rapid genetic changes in the bacterial population in the human stomach. Our data suggest that humans are infected with a population of closely related strains that vary at a small number of gene loci, that this population of strains may already be present when an infection is acquired, and that even during superinfection genetic exchange among distinct strains is rare.

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“…Genetic variations in this bacterium during its chronic infection can be one of the main causes of treatment failure through the emergence of newly evolved resistant H. pylori strains in each patient (9). However, this failure could also be caused by coinfection with diverse strains presenting different resistance phenotypes (2).…”

Section: Introductionmentioning

confidence: 99%

“…Helicobacter pylori is a gram-negative, microaerophilic bacterium that was established as an etiological agent of chronic gastritis, peptic ulcer, mucosal-associated lymphoid tissue (MALT) lymphoma, and gastric cancer (1)(2)(3)(4). Greater than 50z of people in the world are infected with this bacterium (5).…”

Section: Introductionmentioning

confidence: 99%

Genotype Diversity and Quasispecies Development of <i>Helicobacter pylori</i> in a Single Host

et al. 2015

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SUMMARY:Infection with different strains of Helocobacter pylori and emergence of new genomic variants during their long-term gastric colonization are assumed to be the main reasons for eradication failure. We used genotyping and arbitrarily primed PCR fingerprinting (RAPD) to detect relatedness and genetic variations among H. pylori single isolates from each patient in Iran. Multiplex-PCR amplification of gene alleles encoding the virulence factors vacA (m/s), cagA, and iceA (A1/A2) and comparison of RAPD patterns of different singles colonies were performed for each individual patient's isolate. Results showed a high frequency of diversity among the H. pylori strains. Nearly 23z of infected patients showed a single type infection. The infection types related, unrelated, and related/unrelated were found among 25.6z, 12.8z, and 38.5z of patients, respectively. Both mixed type infections (77z) and quasispecies development (15.4z) were detected in these patients. Genotype conversion among vacA (41.6z), cagA (41.6z), and iceA (50z) alleles was observed for the strains with identical or related RAPD patterns. Coevolution of different alleles was also detected in a patient infected with strains presenting the same RAPD patterns. Collectively, results of this study revealed the occurrence of quasispecies development, mixed type infections, and changes in virulence properties of H. pylori strains among the studied patients.

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High prevalence of mixed infections by Helicobacter pylori in Hong Kong: metronidazole sensitivity and overall genotype

Cited by 44 publications

References 32 publications

Concordance ofHelicobacter pyloriStrains within Families

Concordance ofHelicobacter pyloriStrains within Families

Genetic Analysis of Helicobacter pylori Strain Populations Colonizing the Stomach at Different Times Postinfection

Genotype Diversity and Quasispecies Development of <i>Helicobacter pylori</i> in a Single Host

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