title: Prevalence and characterization of plasmid-mediated quinolone resistance genes in extended-spectrum β-lactamase-producing Enterobacteriaceae isolates in Mexico.
abstract: The objectives of this study were to investigate the prevalence of plasmid-mediated quinolone resistance genes in a collection of 226 extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae isolates and characterize the qnr-positive isolates. The rate of qnr-positive isolates was 21.6% (49/226), 49.5% for aac(6')-Ib-cr (112/226), and 1.7% for qepA1 (4/226). Those isolates carried qnr genes corresponding to types qnrB (71.4%), qnrS1 (24.4%), and qnrA1 (18.3%). The distribution among bacterial species was as follows: 55.8% (19/34) to Enterobacter cloacae, 50% (28/56) to Klebsiella pneumoniae, and 1.4% (2/136) to Escherichia coli. The characterization of qnr-positive isolates indicated the ESBL SHV-types as the most prevalent (81.6%), including the ESBLs SHV-12, SHV-5, and SHV-2a, followed by CTX-M-15 (44.9%) and TLA-1 (8.1%). In addition, for qnr-positive isolates, the prevalence of aac(6')-Ib-cr was 55.1%, but qepA was not identified. Alterations at codons Ser-83 and Asp-87 in GyrA and at codons Ser-80 in ParC were observed in 69% and 80% of the qnr-positive isolates, respectively. The analysis of the transconjugants revealed a cotransmission of bla(CTX-M-15) with qepA1 or aac(6')-Ib-cr and/or qnrA1 and bla(SHV-type) with qnrB5 and qnrB6 genes. To conclude, these findings indicate a high prevalence of qnr and aac(6')-Ib-cr among ESBL-producing isolates from Mexican hospitals and point to the wide spread of qnr-like determinants associated to ESBLs SHV- and CTX-M-type in Mexican clinical isolates.
authors.affiliation: Departamento de Diagnóstico Epidemiológico, Instituto Nacional de Salud Pública, CISEI, Avenida Universidad 655, Cuernavaca, Morelos, México.
authors.forename: Jesus
authors.initials: J
authors.lastname: Silva-Sanchez
authors.forename: Humberto
authors.initials: H
authors.lastname: Barrios
authors.forename: Fernando
authors.initials: F
authors.lastname: Reyna-Flores
authors.forename: Margarita
authors.initials: M
authors.lastname: Bello-Diaz
authors.forename: Alejandro
authors.initials: A
authors.lastname: Sanchez-Perez
authors.forename: Teresa
authors.initials: T
authors.lastname: Rojas
authors.forename: Ulises
authors.initials: U
authors.lastname: Garza-Ramos
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D003227:Conjugation, Genetic; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000453:epidemiology* / Q000382:microbiology; D006801:Humans; D008800:Mexico / Q000453:epidemiology; D010957:Plasmids / Q000235:genetics*; D015995:Prevalence; D015363:Quinolones / Q000494:pharmacology*; D001618:beta-Lactamases / Q000096:biosynthesis*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015363:Quinolones; D001618:beta-Lactamases