title: Enteroaggregative Escherichia coli O78:H10, the cause of an outbreak of urinary tract infection.
abstract: In 1991, multiresistant Escherichia coli O78:H10 strains caused an outbreak of urinary tract infections in Copenhagen, Denmark. The phylogenetic origin, clonal background, and virulence characteristics of the outbreak isolates, and their relationship to nonoutbreak O78:H10 strains according to these traits and resistance profiles, are unknown. Accordingly, we extensively characterized 51 archived E. coli O78:H10 isolates (48 human isolates from seven countries, including 19 Copenhagen outbreak isolates, and 1 each of calf, avian, and unknown-source isolates), collected from 1956 through 2000. E. coli O78:H10 was clonally heterogeneous, comprising one dominant clonal group (61% of isolates, including all 19 outbreak isolates) from ST10 (phylogenetic group A) plus several minor clonal groups (phylogenetic groups A and D). All ST10 isolates, versus 25% of non-ST10 isolates, were identified by molecular methods as enteroaggregative E. coli (EAEC) (P < 0.001). Genes present in >90% of outbreak isolates included fimH (type 1 fimbriae; ubiquitous in E. coli); fyuA, traT, and iutA (associated with extraintestinal pathogenic E. coli [ExPEC]); and sat, pic, aatA, aggR, aggA, ORF61, aaiC, aap, and ORF3 (associated with EAEC). An outbreak isolate was lethal in a murine subcutaneous sepsis model and exhibited characteristic EAEC "stacked brick" adherence to cultured epithelial cells. Thus, the 1991 Copenhagen outbreak was caused by a tight, non-animal-associated subset within a broadly disseminated O78:H10 clonal group (ST10; phylogenetic group A), members of which exhibit both ExPEC and EAEC characteristics, whereas O78:H10 isolates overall are phylogenetically diverse. Whether ST10 O78:H10 EAEC strains are both uropathogenic and diarrheagenic warrants further investigation.
authors.affiliation: Department of Clinical Microbiology, Hillerød Hospital, 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: Rebecca L
authors.initials: RL
authors.lastname: Andersen
authors.forename: Megan
authors.initials: M
authors.lastname: Menard
authors.forename: Nadia
authors.initials: N
authors.lastname: Boisen
authors.forename: Brian
authors.initials: B
authors.lastname: Johnston
authors.forename: Dennis S
authors.initials: DS
authors.lastname: Hansen
authors.forename: Karen A
authors.initials: KA
authors.lastname: Krogfelt
authors.forename: James P
authors.initials: JP
authors.lastname: Nataro
authors.forename: James R
authors.initials: JR
authors.lastname: Johnson
mesh_terms: D000818:Animals; D002648:Child; D016000:Cluster Analysis; D003718:Denmark / Q000453:epidemiology; D004195:Disease Models, Animal; D004196:Disease Outbreaks; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D007231:Infant, Newborn; D051379:Mice; D017720:Molecular Epidemiology; D058889:Molecular Typing; D010802:Phylogeny; D018805:Sepsis / Q000401:mortality; D012703:Serotyping; D016019:Survival Analysis; D014552:Urinary Tract Infections / Q000453:epidemiology* / Q000382:microbiology