title: Clarithromycin resistance and prevalence of Helicobacter pylori virulent genotypes in patients from Southern México with chronic gastritis.
abstract: In developing countries, clarithromycin resistance and frequency of re-infection are factors that contribute to high prevalence of Helicobacter pylori infection. The aim of this research was determine the prevalence of clarithromycin resistance and its relation with A2142G, A2142C and A2143G mutations in the domain V of the 23S rRNA gene of H. pylori isolates in patients from Southern Mexico with chronic gastritis. Another purpose of this work was to study the prevalence of virulent genotypes and distribution of resistant strains according to the vacA/cagA/babA2 H. pylori genotypes. One hundred forty-four patients with chronic gastritis were studied. Forty-five H. pylori strains were isolated and clarithromycin susceptibility was determined by the disk-diffusion method. The 82.2% of the strains had the combination of alleles vacA s1 m1 and the cagA gene was detected in 77.8% and 40% of the strains were babA2 positive. The vacA s1 m1 genotype was detected more frequently in cagA(+) strains, vacA s1m1/cagA(+)/babA2(-) genotype was more frequent than vacA s1m1/cagA(+)/babA2(+), 37.8% and 33.3%, respectively. Eight strains were clarithromycin resistant, in three of these, point mutations were identified, but only in one strain the A2143G mutation associated with clarithromycin resistance was found. Other point mutations (A1821G, G1826A, T1830C, A2089G, T1600C, C1601T, C1602T, T1610C, A1611C and T1633G) that have not been associated with clarithromycin resistance were identified. The highest proportion of resistant strains was vacA s1m1/cagA(+) (62.5%). In patients from southern Mexico with chronic gastritis, the prevalence of clarithromycin resistance is within internationally accepted range (17.8%) and allows continued use of triple therapy for H. pylori eradication. However, it is necessary to monitor the evolution of clarithromycin resistance in this area. The largest proportion of resistant H. pylori strains is not harboring the A2142G, A2142C and A2143G mutations in the 23S rRNA gene (87.5%). The vacA s1m1/cagA(+) genotype was the most prevalent and among clarithromycin-resistant strains, this was the predominant.
authors.affiliation: Laboratorio de Investigación en Bacteriología, Unidad Académica de Ciencias Químico Biológicas, Universidad Autónoma de Guerrero, Chilpancingo, Guerrero, México. Electronic address: judmi_7@hotmail.com.
authors.forename: Judit
authors.initials: J
authors.lastname: Alarcón-Millán
authors.affiliation: Laboratorio de Investigación Clínica, Unidad Académica de Ciencias Químico Biológicas, Universidad Autónoma de Guerrero, Chilpancingo, Guerrero, México. Electronic address: gferti@hotmail.com.
authors.forename: Gloria
authors.initials: G
authors.lastname: Fernández-Tilapa
authors.affiliation: Laboratorio de Biología Molecular del Cáncer, Unidad de Investigación, Hospital Juárez de México, Ciudad de México, México. Electronic address: emcortes@cinvestav.mx.
authors.forename: Enoc Mariano
authors.initials: EM
authors.lastname: Cortés-Malagón
authors.affiliation: Hospital de Alta Especialidad, Oaxaca, Oaxaca, México. Electronic address: carlos.ctn@gmail.com.
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: Castañón-Sánchez
authors.affiliation: Hospital General "Dr. Raymundo Abarca Alarcón", Chilpancingo, Guerrero, México. Electronic address: dr.jdsr@hotmail.com.
authors.forename: José
authors.initials: J
authors.lastname: De Sampedro-Reyes
authors.affiliation: Hospital General "Dr. Raymundo Abarca Alarcón", Chilpancingo, Guerrero, México; Unidad Especializada de Gastroenterología Endoscopia, Chilpancingo, Guerrero, México. Electronic address: d_r_cruz@hotmail.com.
authors.forename: Iván
authors.initials: I
authors.lastname: Cruz-Del Carmen
authors.affiliation: Unidad Especializada de Gastroenterología Endoscopia, Chilpancingo, Guerrero, México. Electronic address: rbetancourtl@hotmail.com.
authors.forename: Reyes
authors.initials: R
authors.lastname: Betancourt-Linares
authors.affiliation: Laboratorio de Investigación en Bacteriología, Unidad Académica de Ciencias Químico Biológicas, Universidad Autónoma de Guerrero, Chilpancingo, Guerrero, México. Electronic address: arroman6046@gmail.com.
authors.forename: Adolfo
authors.initials: A
authors.lastname: Román-Román
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000942:Antigens, Bacterial / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D002908:Chronic Disease; D017291:Clarithromycin / Q000494:pharmacology*; D003430:Cross-Sectional Studies; D024881:Drug Resistance, Bacterial / Q000187:drug effects / Q000235:genetics; D005260:Female; D005756:Gastritis / Q000453:epidemiology / Q000382:microbiology*; D016481:Helicobacter Infections / Q000150:complications / Q000453:epidemiology / Q000382:microbiology*; D016480:Helicobacter pylori / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity*; D006801:Humans; D008297:Male; D008800:Mexico / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009154:Mutation; D012338:RNA, Ribosomal, 23S; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D012338:RNA, Ribosomal, 23S; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori; D017291:Clarithromycin
keywords: Clarithromycin; Disk-diffusion; Helicobacter pylori; Resistance; Virulence genotypes