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.com
Volume 7, Issue 2 (Suppl)
J Ecosyst Ecography, an open access journal
ISSN:2157-7625
September 18-20, 2017
September 18-20, 2017 Toronto, Canada
Joint Conference
International Conference on
International Conference on
Environmental Microbiology and Microbial Ecology
&
Ecology and Ecosystems
In vitro
co-culture of commensal
Escherichia coli
strains enhances Stx2a production by the German
E. coli
O104:H4 outbreak strain
Yongxiang Zhang
1
, Lu-Ya Wang
1
, Chad Laing
1
, Roger Johnson
2
, Cassandra Jokinen
1
, James Thomas
3
and
Victor Gannon
1
1
National Microbiology Laboratory at Lethbridge, Canada
2
National Microbiology Laboratory at Guelph, Canada
3
University of Lethbridge, Canada
I
n 2011, a novel shiga toxin-producing
E. coli
(STEC) O104:H4 strainwas associated with a large foodborne disease outbreak centered
in Germany. The outbreak was characterized by a much higher rate of the hemolytic uremic syndrome (HUS) than typically occurs
following STEC O157:H7 infections. Interestingly, this O104:H4 strain produced much lower levels of Stx2a than an STEC O157:H7
outbreak strain in the laboratory. Because the amount of Stx2a produced by O157:H7 strains is correlated with the development of
severe clinical illness, such as STEC-associated HUS in humans, we wished to see if Stx2a-encoding phages released by these two
STEC strains would increase toxin production by infecting commensal
E. coli.
In this study, we examined the role of commensal
non-STEC in amplifying Shiga toxin 2a (Stx2a) production by the toxin-encoding phage released spontaneously from STEC.
Co-incubation of
E. coli
K-12 C600 with the STEC O104:H4 strain ON-2011 and O157:H7 strain
EDL933
resulted in 21-and 8-fold
increases in shiga toxin production, respectively. However, among commensal non-STEC, only isolates of serotypes OR:H19 and
O46:H31 from two of ten human fecal samples significantly increased Stx2a production following co-incubation with ON-2011,
and no increase was observed following co-incubation of commensal
E. coli
with
EDL933
. While stable Stx2a phage ΦON-2011
and 933W
E. coli
C600 lysogens were readily isolated following co-culture with these two pathogens, only ΦON-2011 lysogens were
isolated following co-incubation with the commensal
E. coli.
Two genes encoding putative phage receptor-binding determinants were
present in the ΦON-2011 genome but not that of 933W. While further study is required, it seems likely that differences in 933w and
ΦON2011 commensal
E. coli
host range may result in variability in the levels of Stx2a produced in certain individuals during the
course of infection which could contribute to differences in the severity of STEC-associated disease.
Biography
Yongxiang Zhang is a biologist from National Microbiology Laboratory of public health agency of Canada. He has experience in studying the evolution and virulence
of shiga toxin-producing
Escherichia coli
and the shiga toxin-encoding phage.
Yongxiang.zhang@canada.caYongxiang Zhang, J Ecosyst Ecography 2017, 7:2 (Suppl)
DOI: 10.4172/2157-7625-C1-029