title: Presence of plasmid-mediated quinolone resistance determinants and mutations in gyrase and topoisomerase in Salmonella enterica isolates with resistance and reduced susceptibility to ciprofloxacin.
abstract: In recent decades, the emergence and spread of resistance to nalidixic acid are usually associated with reduced susceptibility to ciprofloxacin among Salmonella serotypes. The aims of this study were to investigate the mechanisms associated with resistance to fluoroquinolone and the clonal relatedness of Salmonella strains isolated from human and nonhuman origins, in a 5-year period in São Paulo, Brazil. Antimicrobial susceptibility testing for Salmonella isolates was performed. PCR and DNA sequencing were accomplished to identify mutations in the quinolone resistance-determining regions of the topoisomerase genes and to determine the fluoroquinolone determinants. The strains presented MIC to ciprofloxacin ranging from 0.125 to 8.0 mg/L (all nonsusceptible). From these, 16 strains (17.5%) were resistant to ciprofloxacin (MIC ≥1 mg/L) and belonging to serotypes Typhimurium, I. 4,5,12:i:-, Enteritidis, and Heidelberg. Amplification and DNA sequencing of topoisomerases genes identified multiple amino acid substitutions in GyrA and ParC. No mutations were identified in GyrB, and 1 amino acid substitution was identified in ParE. Among the 16 Salmonella strains resistant to ciprofloxacin, 8 S. I. 4,5,12:i:- presenting mutations in gyrA and parE genes were grouped into the same pulsotype. Plasmid-mediated quinolone resistance (PMQR) determinants: qnrB, aac(6')-lb-cr, and oqxA/B were detected among 13 strains. To the best of our knowledge, this is the first work to report Salmonella isolates resistant to ciprofloxacin in Brazil. Indeed, this is the first detection of PMQR determinants in Salmonella strains from Sao Paulo State. These findings alert for the potential spread of quinolone resistance of Salmonella strains, particularly in S. I. 4,5,12:i:-, a prevalent serotype implicated in human disease and foodborne outbreaks.
authors.affiliation: Núcleo de Doenças Entéricas e Infecções por Patógenos Especiais, Centro de Bacteriologia, Instituto Adolfo Lutz, São Paulo, Brazil. Electronic address: mrtiba@yahoo.com.br.
authors.forename: Monique Ribeiro Tiba
authors.initials: MR
authors.lastname: Casas
authors.affiliation: Núcleo de Doenças Entéricas e Infecções por Patógenos Especiais, Centro de Bacteriologia, Instituto Adolfo Lutz, São Paulo, Brazil.
authors.forename: Carlos Henrique
authors.initials: CH
authors.lastname: Camargo
authors.affiliation: Núcleo de Doenças Entéricas e Infecções por Patógenos Especiais, Centro de Bacteriologia, Instituto Adolfo Lutz, São Paulo, Brazil.
authors.forename: Flávia Barrosa
authors.initials: FB
authors.lastname: Soares
authors.affiliation: Laboratório de Biologia Molecular Bacteriana, Universidade Estadual de Campinas, Campinas, Brazil.
authors.forename: Wanderley Dias
authors.initials: WD
authors.lastname: da Silveira
authors.affiliation: Núcleo de Doenças Entéricas e Infecções por Patógenos Especiais, Centro de Bacteriologia, Instituto Adolfo Lutz, São Paulo, Brazil.
authors.forename: Sueli Aparecida
authors.initials: SA
authors.lastname: Fernandes
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D001938:Brazil; D027081:DNA Gyrase / Q000235:genetics*; D026942:DNA Topoisomerases / Q000235:genetics*; D024881:Drug Resistance, Bacterial; D024841:Fluoroquinolones / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D009154:Mutation; D010957:Plasmids / Q000235:genetics*; D012480:Salmonella Infections / Q000453:epidemiology / Q000382:microbiology; D019779:Salmonella enterica / Q000145:classification / Q000187:drug effects* / Q000235:genetics*; D065288:Serogroup
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D024841:Fluoroquinolones; D026942:DNA Topoisomerases; D027081:DNA Gyrase
keywords: Fluoroquinolones; Molecular epidemiology; Plasmid; Salmonella