title: Analysis of the genotypic diversity of strains of Helicobacter pylori isolated from pediatric patients in Mexico.
abstract: Genotypic differences in Helicobacter pylori play an important role in infection. We characterized the diversity of the cagA, cagE, babA2, and vacA genes in H. pylori strains isolated from pediatric patients and the relationship between these genes and clinical disease. Additionally, we employed the Neighbor-net algorithm to predict the behavior of the genotypes of the strains isolated from patients. Of 93 patients analyzed, 32 were positive for infection. A total of 160 H. pylori strains (five isolates per positive patient) were analyzed. A total of 91% and 83% of strains possessed the cagA and cagE genes, respectively. For the vacA gene, 84% of strains possessed the s1 allele, 15% the s2 allele, 81% the m1 allele and 13.8% the m2 allele. The babA2 gene was present in 79% of strains. Infection with H. pylori strains with the vacA (s1m1) genotype was associated with risk of esophagitis and gastritis (p=0.0001). The combination of cagA and vacA (s1m1) was significantly associated with abdominal pain (p=0.002); however, EPIYA type was not significantly associated with abdominal pain. A total of 16 different genotypes were identified; the most common genotype was vacAs1m1cagA+cagE+babA2+ (47.5%). A total of 84% of pediatric patients were infected by at least two and up to five different genotypes. The network recovered two genotype groups (A: strains with vacAs1 and B: strains with vacAs2). The presence of multiple paths in the network suggests that reticulate events, such as recombination or reinfection, have contributed to the observed genotypic diversity.
authors.affiliation: Laboratorio de Infectologia, Hospital Infantil de México Federico Gómez, México D.F., Mexico; Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, México D.F., Mexico.
authors.forename: S
authors.initials: S
authors.lastname: Mendoza-Elizalde
authors.affiliation: Laboratorio de Infectologia, Hospital Infantil de México Federico Gómez, México D.F., Mexico; Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, México D.F., Mexico.
authors.forename: A C
authors.initials: AC
authors.lastname: Cortés-Márquez
authors.affiliation: Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, México D.F., Mexico.
authors.forename: S
authors.initials: S
authors.lastname: Giono-Cerezo
authors.affiliation: Departamento de Zoología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, México D.F., Mexico.
authors.forename: G
authors.initials: G
authors.lastname: Zuñiga
authors.affiliation: Departamento de Gastroenterología y Nutrición, Hospital Infantil de México Federico Gómez, México D.F., Mexico.
authors.forename: A
authors.initials: A
authors.lastname: Consuelo-Sánchez
authors.affiliation: Departamento de Patología, Hospital Infantil de México Federico Gómez, México D.F., México.
authors.forename: P
authors.initials: P
authors.lastname: Valencia-Mayoral
authors.affiliation: Laboratorio de Infectologia, Hospital Infantil de México Federico Gómez, México D.F., Mexico.
authors.forename: J C
authors.initials: JC
authors.lastname: Vigueras-Galindo
authors.affiliation: Laboratorio de Infectologia, Hospital Infantil de México Federico Gómez, México D.F., Mexico.
authors.forename: G
authors.initials: G
authors.lastname: Escalona-Venegas
authors.affiliation: Laboratorio de Infectologia, Hospital Infantil de México Federico Gómez, México D.F., Mexico.
authors.forename: J
authors.initials: J
authors.lastname: Arellano-Galindo
authors.affiliation: Laboratorio de Infectologia, Hospital Infantil de México Federico Gómez, México D.F., Mexico. Electronic address: normave@himfg.edu.mx.
authors.forename: N
authors.initials: N
authors.lastname: Velázquez-Guadarrama
mesh_terms: D000293:Adolescent; D000465:Algorithms; D001426:Bacterial Proteins / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D019295:Computational Biology / Q000379:methods; D014644:Genetic Variation; D005838:Genotype; D016481:Helicobacter Infections / Q000382:microbiology* / Q000473:pathology; D016480:Helicobacter pylori / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D006801:Humans; D007223:Infant; D008800:Mexico; D017422:Sequence Analysis, DNA; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D037521:Virulence Factors
keywords: Children; EPIYA; Helicobacter pylori; babA2; cagA; vacA