title: Temporal trends in antimicrobial resistance and virulence-associated traits within the Escherichia coli sequence type 131 clonal group and its H30 and H30-Rx subclones, 1968 to 2012.
abstract: To identify possible explanations for the recent global emergence of Escherichia coli sequence type (ST) 131 (ST131), we analyzed temporal trends within ST131 O25 for antimicrobial resistance, virulence genes, biofilm formation, and the H30 and H30-Rx subclones. For this, we surveyed the WHO E. coli and Klebsiella Centre's E. coli collection (1957 to 2011) for ST131 isolates, characterized them extensively, and assessed them for temporal trends. Overall, antimicrobial resistance increased temporally in prevalence and extent, due mainly to the recent appearance of the H30 (1997) and H30-Rx (2005) ST131 subclones. In contrast, neither the total virulence gene content nor the prevalence of biofilm production increased temporally, although non-H30 isolates increasingly qualified as extraintestinal pathogenic E. coli (ExPEC). Whereas virotype D occurred from 1968 forward, virotypes A and C occurred only after 2000 and 2002, respectively, in association with the H30 and H30-Rx subclones, which were characterized by multidrug resistance (including extended-spectrum-beta-lactamase [ESBL] production: H30-Rx) and absence of biofilm production. Capsular antigen K100 occurred exclusively among H30-Rx isolates (55% prevalence). Pulsotypes corresponded broadly with subclones and virotypes. Thus, ST131 should be regarded not as a unitary entity but as a group of distinctive subclones, with its increasing antimicrobial resistance having a strong clonal basis, i.e., the emergence of the H30 and H30-Rx ST131 subclones, rather than representing acquisition of resistance by diverse ST131 strains. Distinctive characteristics of the H30-Rx subclone-including specific virulence genes (iutA, afa and dra, kpsII), the K100 capsule, multidrug resistance, and ESBL production-possibly contributed to epidemiologic success, and some (e.g., K100) might serve as vaccine targets.
authors.affiliation: Department of Clinical Microbiology, Herlev Hospital, Herlev, Denmark bente.ruth.scharvik.olesen@regionh.dk.
authors.forename: Bente
authors.initials: B
authors.lastname: Olesen
authors.affiliation: Department of Clinical Microbiology, Herlev Hospital, Herlev, Denmark Department of Microbiology and Infection Control, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Jakob
authors.initials: J
authors.lastname: Frimodt-Møller
authors.affiliation: Department of Microbiology and Infection Control, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Rikke Fleron
authors.initials: RF
authors.lastname: Leihof
authors.affiliation: Department of Microbiology and Infection Control, Statens Serum Institut, Copenhagen, Denmark WHO Collaborating Centre for Reference and Research on Escherichia and Klebsiella, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Carsten
authors.initials: C
authors.lastname: Struve
authors.affiliation: Veterans Affairs Medical Center and University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Johnston
authors.affiliation: Department of Clinical Microbiology, Herlev Hospital, Herlev, Denmark.
authors.forename: Dennis S
authors.initials: DS
authors.lastname: Hansen
authors.affiliation: Department of Microbiology and Infection Control, Statens Serum Institut, Copenhagen, Denmark WHO Collaborating Centre for Reference and Research on Escherichia and Klebsiella, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Flemming
authors.initials: F
authors.lastname: Scheutz
authors.affiliation: Department of Microbiology and Infection Control, Statens Serum Institut, Copenhagen, Denmark WHO Collaborating Centre for Reference and Research on Escherichia and Klebsiella, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Krogfelt
authors.affiliation: Veterans Affairs Medical Center and University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kuskowski
authors.affiliation: Veterans Affairs Medical Center and University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Connie
authors.initials: C
authors.lastname: Clabots
authors.affiliation: Veterans Affairs Medical Center and University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: James R
authors.initials: JR
authors.lastname: Johnson
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics*; D018441:Biofilms; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D011135:Polysaccharides, Bacterial / Q000235:genetics*; D065288:Serogroup; D022603:Shiga Toxins / Q000096:biosynthesis; D037521:Virulence Factors / Q000235:genetics*; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000942:Antigens, Bacterial; D011135:Polysaccharides, Bacterial; D022603:Shiga Toxins; D037521:Virulence Factors; D001618:beta-Lactamases