title: Prevalence of qnr determinants among extended-spectrum beta-lactamase-positive Enterobacteriaceae clinical isolates in southern Stockholm, Sweden.
abstract: Three hundred and nineteen extended-spectrum beta-lactamase-positive Enterobacteriaceae clinical isolates were screened for qnr genes. Twelve isolates were positive for qnr, including one qnrA1, two qnrB1, three qnrB2, one qnrB4, one qnrB6 and four qnrS1. No qnr-positive strains were identified among the isolates recovered before 2006. The first qnr-positive Escherichia coli was detected from a patient in 2006. qnr genes remained rare in E. coli (6/288; 2.1%), but appeared to be more prevalent in Klebsiella pneumoniae (4/25; 16%) and Enterobacter cloacae (2/3; 66.7%). All qnr-positive isolates were resistant to nalidixic acid while presenting varied susceptibilities to fluoroquinolones. Isolates harbouring qnrB4 or qnrB6 were highly resistant to all the fluoroquinolones tested. Their high-level resistance is associated with multiple chromosomal substitutions in gyrA and parC. Alterations at codons Ser-83 and Asp-87 in GyrA and at codons Ser-80 and Glu-84 in ParC were observed in these isolates.
authors.affiliation: Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska University Hospital Huddinge, Karolinska Institutet, SE-141 86 Stockholm, Sweden.
authors.forename: Hong
authors.initials: H
authors.lastname: Fang
authors.forename: Haihui
authors.initials: H
authors.lastname: Huang
authors.forename: Yuejie
authors.initials: Y
authors.lastname: Shi
authors.forename: Göran
authors.initials: G
authors.lastname: Hedin
authors.forename: Carl Erik
authors.initials: CE
authors.lastname: Nord
authors.forename: Måns
authors.initials: M
authors.lastname: Ullberg
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D016972:Enterobacter cloacae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D004756:Enterobacteriaceae Infections / Q000453:epidemiology* / Q000382:microbiology; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D024841:Fluoroquinolones / Q000494:pharmacology; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D009268:Nalidixic Acid / Q000494:pharmacology; D015995:Prevalence; D013548:Sweden / Q000453:epidemiology; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D024841:Fluoroquinolones; C485385:Qnr protein, Klebsiella pneumoniae; D009268:Nalidixic Acid; D001618:beta-Lactamases; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase