Affiliation:
1. Department of Clinical Microbiology, Hillerød Hospital, Hillerød, Denmark
2. WHO Collaborating Centre for Reference and Research on Escherichia and Klebsiella, Statens Serum Institut, Copenhagen, Denmark
3. Veterans Affairs Medical Center and Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
4. University of Virginia School of Medicine, Department of Pediatrics, Charlottesville, Virginia, USA
5. Department of Microbiological Surveillance and Research, Statens Serum Institut, Copenhagen, Denmark
Abstract
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.
Publisher
American Society for Microbiology