title: Tn7 distribution in Helicobacter pylori: a selective paradox.
abstract: The presence of class 1, 2 and 3 integrons in Helicobacter pylori, which in other species are usually related to antimicrobial resistance, were looked for in 40 epidemiologically-unrelated isolates. The presence of the class 2 integrase, which led to the discovery of Tn7, was found in 15 of 35 different clones identified by lspA-glmM polymorphism. MIC values for trimethoprim and streptomycin were not affected by the presence or absence of dfrA1 and aadA1 genes. The polyclonal spread of Tn7 showed the ability of H. pylori to harbour antimicrobial resistance mechanisms, usually located on plasmids, and also suggested that other important mechanisms of resistance may also be acquired, which would result in failure of chemotherapy.
authors.affiliation: Departamento de Microbiología, Parasitología e Inmunología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Paraguay 2155, P-12, Capital Federal, Argentina.
authors.forename: Oscar
authors.initials: O
authors.lastname: Crespo
authors.forename: Mariana
authors.initials: M
authors.lastname: Catalano
authors.forename: Silvia
authors.initials: S
authors.lastname: Piñeiro
authors.forename: Mario
authors.initials: M
authors.lastname: Matteo
authors.forename: Alejandro
authors.initials: A
authors.lastname: Leanza
authors.forename: Daniela
authors.initials: D
authors.lastname: Centrón
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004251:DNA Transposable Elements; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D016481:Helicobacter Infections / Q000453:epidemiology* / Q000382:microbiology; D016480:Helicobacter pylori / Q000187:drug effects* / Q000235:genetics*; D006801:Humans; D019426:Integrases / Q000235:genetics; D032023:Integrons / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D010437:Peptic Ulcer / Q000453:epidemiology* / Q000382:microbiology; D016133:Polymerase Chain Reaction; D013307:Streptomycin / Q000494:pharmacology; D014295:Trimethoprim / Q000494:pharmacology; D014296:Trimethoprim Resistance
chemical_list: D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D014295:Trimethoprim; D019426:Integrases; D013307:Streptomycin