Usefulness and influence of age of a novel Rapid HpStAR stool antigen for the diagnosis of Helicobacter pylori infection in children.

A novel rapid monoclonal enzyme immunoassay stool antigen for Helicobacter pylori detection (Rapid HpStAR) was evaluated in 16 infected and 92 noninfected children. The overall sensitivity, specificity, and positive and negative predictive values were 87.5%, 97.8%, 87.5%, and 97.8%, respectively, with an accuracy of 96.2%. The negative predictive value was good in all age groups, reaching 100% in younger children.

Using macro-arrays to study routes of infection of Helicobacter pylori in three families.

BACKGROUND: Analysis of the evolutionary dynamics of Helicobacter pylori allowed tracing the spread of infection through populations on different continents but transmission pathways between individual humans have not been clearly described. MATERIALS AND METHODS: To investigate person-to-person transmission, we studied three families each including one child with persistence of symptoms after antibiotic treatment. Ten isolates from the antrum and corpus of stomach of each family member were analyzed both by sequencing of two housekeeping genes and macroarray tests. RESULTS: A total of 134 (8.4%) out of the 1590 coding sequences (CDSs) tested, including cag PAI and insertion sequences, were present in some but not all isolates (and are therefore defined as variable CDSs). Most of the variable CDSs encoded proteins of unknown function (76/134) or were selfish DNA including that encoding restriction/modification enzymes (13/134). Isolates colonizing the stomach of one individual can vary by point mutations, as seen in hspA, or by the gain or loss of one to five CDSs. They were considered as (genetic) variants. The phylogenetic clustering of gene profiles obtained on macro-arrays allowed identifying the different strains infecting families. Two to five strains circulated within a family. Identical strains were present in at least two members of all three families supporting the accepted model of intrafamilial transmission. Surprisingly, the mother was not implicated in the transmission of H. pylori in the two French families. Sibling-to-sibling transmission and acquisition of H. pylori from outside the family appeared to be probable in the transmission pathways. CONCLUSION: Macroarray analysis based on previously selected CDSs gives a comprehensive view of the genome diversity of a pathogen. This approach combined with information on the origin of the hspA and glmM alleles revealed that Helicobacter pylori infection may be acquired by more diverse routes than previously expected.

[Helicobacter pylori infection in children]. / Infection à Helicobacter pylori chez l'enfant.

Knowledge about Helicobacter pylori infection in children continues to advance. While its prevalence appears to be falling in developed countries, it remains a major problem in developing nations. Its transmission pathway remains highly controversial. It has not yet been definitively elucidated, although the oral-oral route seems most probable. Infection is most often intrafamilial. Risk factors for infection are associated with low socioeconomic level, including overcrowding, unhygienic conditions, sharing beds in childhood, low maternal educational level. Infection in children differs from that in adults in three respects: symptoms, endoscopic appearance of the gastric mucosa, and histologic appearance of lesions. No study has established a clear association between recurrent abdominal pain and H. pylori infection. Nonetheless, in proven infections, recurrent abdominal pain is the most common marker. More recently, an association has been reported between H. pylori infection and iron deficiency anemia. The endoscopic aspect most suggestive of H. pylori infection in children is micronodular gastritis, but it is not specific to H. pylori infection. In children as in adults, H. pylori infection is always associated with histologic gastritis. Many questions about H. pylori remain unanswered, and numerous studies are still needed.

Helicobacter pylori primary resistant strains over 11 years in French children.

The yearly prevalence between 1994 and 2005 of primary resistance to amoxicillin, metronidazole, and clarithromycin of 377 Helicobacter pylori strains isolated from children was studied. All the H. pylori strains were susceptible to amoxicillin, 138/377 (36.7%) were resistant to metronidazole, 86/377 (22.8%) to clarithromycin, and 30/377 (7.9%) to both metronidazole and clarithromycin. Over the entire period, resistance to clarithromycin did not change, whereas metronidazole resistance decreased significantly from 43.3% (1994-1998) to 32% (1999-2005), P = 0.001.

Clarithromycin resistance in Helicobacter pylori strains isolated from French children: prevalence of the different mutations and coexistence of clones harboring two different mutations in the same biopsy.

BACKGROUND: The aim of our study was to assess the different mutations involved in clarithromycin-resistant Helicobacter pylori strains isolated from French children and their temporal trends. METHODS: The point mutations of H. pylori were detected by PCR followed by RFLP technique in 50 clarithromycin-resistant strains collected between 1993 and 2004 in France. RESULTS: Clarithromycin resistance was observed in 23% (50/217) of H. pylori isolates. Two mutations A2143G and A2142G in the 23S rRNA genes of H. pylori were detected. The former was found in 45/50 (90%) of isolates. The rate of resistance increased with time from 18.6% in the period 1993-1996 to 41.6% in 2001-2004. No significant difference was observed in the distribution of mutations during the same periods. No correlation was found between any mutation and age, sex, and ethnic origin of children. Furthermore, no significant differences in minimal inhibitory concentrations level were observed according to the different point mutations. In all cases, only one point mutation was present, except in two cases where two different mutations were found in two different clones from the same biopsy. CONCLUSION: The mutation A2143G is predominant in clarithromycin-resistant H. pylori strains isolated from children in France. We report for the first time the presence of two clarithromycin-resistant clones harboring two different mutations of the 23S rRNA genes present in the same biopsy specimen and genotypically identical as demonstrated by RAPD fingerprinting.

Heterogeneous susceptibility to metronidazole and clarithromycin of Helicobacter pylori isolates from a single biopsy in adults is confirmed in children.

The aim of this study was to assess the resistance to metronidazole and clarithromycin of individual colonies of Helicobacter pylori from a single biopsy taken from 14 adults and 14 children. The Etest was used to determine the minimum inhibitory concentrations (MICs) of these two antimicrobial drugs for ten individual H. pylori colonies isolated from each initial gastric biopsy culture. We confirmed the heterogeneity in metronidazole and clarithromycin resistance in children as seen in adults before anti-H. pylori treatment. The number of resistant individual colonies ranged from two to nine depending on the subject. All individual colonies from the same biopsy that were resistant to clarithromycin were genetically identical according to randomly amplified polymorphic DNA testing and exhibited the same point mutation according to polymerase chain reaction-restriction fragment length polymorphism.

Usefulness and influence of age of a novel rapid monoclonal enzyme immunoassay stool antigen for the diagnosis of Helicobacter pylori infection in children.

A novel rapid monoclonal enzyme immunoassay stool antigen for Helicobacter pylori detection (Immunocard STAT!HpSA, Meridian Diagnostic Inc , Cincinnati, OH) was evaluated in 29 infected and 99 noninfected children. The overall sensitivity, specificity, and positive and negative predictive values were 86.2%, 92.9%, 78.1%, and 95.8%, respectively, with an accuracy of 91.4%. The highest performance was observed in children older that 10 years, with a sensitivity level of 100%, contrasting with a lower level, 75%, in those younger than 5 years. A good negative predictive value was observed in all age groups, particularly in older children achieving 100%.

Genetic and transmission analysis of Helicobacter pylori strains within a family.

To look for evidence of intrafamilial infection, we isolated 107 Helicobacter pylori clones from biopsied specimens taken from both parents and four children. We compared the sequences of two housekeeping genes (hspA and glmM) from these clones with those of 131 unrelated strains from patients living in different geographic regions. Strain relationships within the family were determined by analyzing allelic variation at both loci and building phylogenetic trees and by using multilocus sequence typing. Both hspA- and glmM-based phylogenetic trees showed East Asian and African branches. All samples from family members showed natural mixed infection. Identical alleles found in some strains isolated from the children and parents, but not in the strains isolated from unrelated patients, demonstrated that strains have circulated within the family. Several mechanisms, such as point mutations, intragenic recombination, and introduction of foreign (African) alleles, were shown to enhance strain diversity within the family.