title: Prevalence of plasmid-mediated quinolone resistance genes in uropathogenic Escherichia coli isolated in a teaching hospital of northern Italy.
abstract: A retrospective study was conducted to determine the prevalence of plasmid-mediated quinolone resistance (PMQR) determinants in uropathogenic Escherichia coli isolated from inpatients and outpatients in a teaching hospital of northern Italy. The presence of qnrA, qnrB, qnrS, aac(6')-Ib-cr, and qepA was evaluated in 76 and 72 nalidixic acid-resistant E. coli, isolated in 2004 and 2006, respectively. Positivity for the aac(6')-Ib-cr gene was demonstrated in 3 of 76 (3.9%) and 8 of 72 (11%) isolates, respectively; no other PMQR determinant was found. All aac(6')-Ib-cr-positive strains also showed two point mutations in the gyrA and parC genes. Most aac(6')-Ib-cr-positive isolates demonstrated the contemporary presence of bla(CTX-M-15), bla(OXA-1/30), and bla(TEM-1) genes and 4/11 harbored a class 1 integron with a dfrA17-aadA5 gene cassette arrangement. Interestingly, all aac(6')-Ib-cr-positive isolates belonged to B2 phylogenetic group, O25b antigen type, multi locus sequence type 131, and to a cluster of approximately 70% similarity level by pulsed-field gel electrophoresis (PFGE). These findings suggest the circulation of the previously described intercontinentally spreading E. coli O25:H4-ST131 clone in our geographical area since 2004. Hybridization studies of the PFGE profiles showed the aac(6')-Ib-cr gene to be associated with different molecular weight bands (40-350 kb) and interestingly aac(6')-Ib-cr chromosomal integration was demonstrated in one strain by I-Ceu I method. This represents the first report to investigate the presence and diffusion of PMQR determinants in northern Italy and to describe aac(6')-Ib-cr chromosomal integration in E. coli.
authors.affiliation: Department of Clinical Medicine and Prevention, University of Milano-Bicocca, Monza (MB), Italy.
authors.forename: Rosario
authors.initials: R
authors.lastname: Musumeci
authors.forename: Marco
authors.initials: M
authors.lastname: Rausa
authors.forename: Roberto
authors.initials: R
authors.lastname: Giovannoni
authors.forename: Anna
authors.initials: A
authors.lastname: Cialdella
authors.forename: Simone
authors.initials: S
authors.lastname: Bramati
authors.forename: Bruno
authors.initials: B
authors.lastname: Sibra
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Giltri
authors.forename: Franco
authors.initials: F
authors.lastname: Viganò
authors.forename: Clementina Elvezia
authors.initials: CE
authors.lastname: Cocuzza
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D004927:Escherichia coli Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000235:genetics*; D006784:Hospitals, Teaching; D006801:Humans; D032023:Integrons; D007558:Italy / Q000453:epidemiology; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D009154:Mutation; D010802:Phylogeny; D010957:Plasmids; D015995:Prevalence; D015363:Quinolones / Q000494:pharmacology*; D012189:Retrospective Studies; D056689:Uropathogenic Escherichia coli / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; C485384:Qnr protein, E coli; D015363:Quinolones; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase