title: Analysis of plasmid-mediated quinolone and oxyimino-cephalosporin resistance mechanisms in Uruguayan Salmonella enterica isolates from 2011-2013.
abstract: This study characterised the mechanisms of fluoroquinolone and oxyimino-cephalosporin resistance in human Salmonella enterica isolates in Uruguay. Salmonella enterica isolates were collected from 2011-2013 and were selected based on non-susceptibility to ciprofloxacin and/or oxyimino-cephalosporins. The disk diffusion assay was performed for various antibiotics, and the ciprofloxacin minimum inhibitory concentration (MIC) was determined following CLSI guidelines. Genetic relatedness was determined following PulseNet protocols. Extended-spectrum β-lactamases, ampC alleles and plasmid-mediated quinolone resistance were characterised by PCR and sequencing. Plasmid analyses were carried out by conjugation or transformation assays, and plasmid-encoded genes were identified by PCR. Mutations in the quinolone resistance-determining region of gyrases were sought by PCR and sequencing. Among 579 isolates, 105 (18.4%) ciprofloxacin-non-susceptible (CIP-NS) isolates, 9 (1.6%) oxyimino-cephalosporin-resistant isolates and 2 (0.3%) isolates resistant to both antibiotic families were detected. Thirteen isolates carried qnrB alleles (twelve qnrB19 and one qnrB2), four carried blaCTX-M-8, two blaCTX-M-14, two blaSHV-2 and three blaCMY-2-like genes. No correlation was found between mutations in gyrases and ciprofloxacin MICs. Several co-circulating clones of S. enterica ssp. enterica serovar Typhimurium were detected; conversely, S. enterica ssp. enterica serovar Enteritidis corresponded mainly to a single circulating clone. Nine (75%) of twelve of CIP-NS extraintestinal isolates shared the same pulsotype with intestinal isolates. During the study period, the frequency of CIP-NS isolates increased, albeit with ciprofloxacin MICs of 0.125-0.5mg/L. Detection of the same quinolone-resistant clones recovered both from intestinal and extraintestinal samples highlights the significance of epidemiological surveillance of antibiotic susceptibility for every human Salmonella isolate.
authors.affiliation: Departamento de Bacteriología y Virología, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Alfredo Navarro 3051, CP: 11600 Montevideo, Uruguay.
authors.forename: Nicolás F
authors.initials: NF
authors.lastname: Cordeiro
authors.affiliation: Departamento de Laboratorios, Ministerio de Salud Pública, Alfredo Navarro 3051, CP: 11600 Montevideo, Uruguay.
authors.forename: Adriana
authors.initials: A
authors.lastname: Nabón
authors.affiliation: Departamento de Bacteriología y Virología, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Alfredo Navarro 3051, CP: 11600 Montevideo, Uruguay; Departamento de Laboratorios, Ministerio de Salud Pública, Alfredo Navarro 3051, CP: 11600 Montevideo, Uruguay.
authors.forename: Virginia
authors.initials: V
authors.lastname: García-Fulgueiras
authors.affiliation: Departamento de Bacteriología y Virología, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Alfredo Navarro 3051, CP: 11600 Montevideo, Uruguay.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Álvez
authors.affiliation: Departamento de Laboratorios, Ministerio de Salud Pública, Alfredo Navarro 3051, CP: 11600 Montevideo, Uruguay.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Sirok
authors.affiliation: Departamento de Laboratorios, Ministerio de Salud Pública, Alfredo Navarro 3051, CP: 11600 Montevideo, Uruguay.
authors.forename: Teresa
authors.initials: T
authors.lastname: Camou
authors.affiliation: Departamento de Bacteriología y Virología, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Alfredo Navarro 3051, CP: 11600 Montevideo, Uruguay. Electronic address: rvignoli@higiene.edu.uy.
authors.forename: Rafael
authors.initials: R
authors.lastname: Vignoli
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018550:Cephalosporin Resistance / Q000235:genetics*; D002939:Ciprofloxacin / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics; D015363:Quinolones / Q000494:pharmacology; D012480:Salmonella Infections; D019779:Salmonella enterica / Q000187:drug effects / Q000235:genetics*; D014583:Uruguay
chemical_list: D000900:Anti-Bacterial Agents; D015363:Quinolones; D002939:Ciprofloxacin
keywords: PMQR; Salmonella; β-Lactamase