title: Three-decade epidemiological analysis of Escherichia coli O15:K52:H1.
abstract: The successful Escherichia coli O15:K52:H1 clonal group provides a case study for the emergence of multiresistant clonal groups of Enterobacteriaceae generally. Accordingly, we tested the hypotheses that, over time, the O15:K52:H1 clonal group has become increasingly (i) virulent and (ii) resistant to antibiotics. One hundred archived international E. coli O15:K52:[H1] clinical isolates from 100 unique patients (1975 to 2006) were characterized for diverse phenotypic and molecular traits. All 100 isolates derived from phylogenetic group D and, presumptively, sequence type ST393. They uniformly carried the F16 papA allele and papG allele II (P fimbria structural subunit and adhesin variants), iha (adhesin-siderophore), fimH (type 1 fimbriae), fyuA (yersiniabactin receptor), iutA (aerobactin receptor), and kpsM II (group 2 capsule); 85% to 89% of them contained a complete copy of the pap operon and ompT (outer membrane protease). Slight additional virulence profile variation was evident, particularly within a minor diarrhea-associated subset (biotype C). However, in contrast to the clonal group's fairly stable virulence profiles over the past 30+ years, during the same interval the clonal group members' antimicrobial resistance profiles increased by a mean of 2.8 units per decade (P < 0.001). Moreover, the numbers of virulence genes and resistance markers were positively associated (P = 0.046), providing evidence against antimicrobial resistance and virulence being mutually exclusive in these strains. Thus, the O15:K52:H1 clonal group has become increasingly resistant to antimicrobials while maintaining (or expanding) its virulence potential, a particularly concerning trend if other emerging multiresistant enterobacterial clonal groups follow a similar pattern.
authors.affiliation: Department of Clinical Microbiology, Hillerød Sygehus, Helsevej 2, DK-3400 Hillerød, Denmark. benol@hih.regionh.dk
authors.forename: Bente
authors.initials: B
authors.lastname: Olesen
authors.forename: Flemming
authors.initials: F
authors.lastname: Scheutz
authors.forename: Megan
authors.initials: M
authors.lastname: Menard
authors.forename: Marianne N
authors.initials: MN
authors.lastname: Skov
authors.forename: Hans Jørn
authors.initials: HJ
authors.lastname: Kolmos
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kuskowski
authors.forename: James R
authors.initials: JR
authors.lastname: Johnson