Transcript VTEC non-O157 serotypes linked with haemolytic uremic

Lienemann T1, Rimhanen-Finne R2, Kuusi M2 and Siitonen A1
1 Bacteriology
Unit and 2 Epidemic Surveillance and Response Unit, National Institute for Health and Welfare (THL), P.O.BOX 30, 00271 Helsinki, Finland
VTEC non-O157 serotypes linked with haemolytic
uraemic syndrome in Finland (1996-2011)
Introduction
Methods
Haemolytic uraemic syndrome (HUS) is the most severe clinical
manifestation of verocytotoxin –producing Escherichia coli
(VTEC). The serotype O157:H7/H- is most frequently associated
with severe disease such as HUS but some non-O157 serotypes
can cause HUS as well. In this study, we report all the detected
non-O157 serotypes which were linked with HUS in Finland
(1996-2011).
In Finland, clinical microbiology laboratories throughout the
country send all human VTEC isolates to the Bacteriology Unit of
THL for confirmation and for further phenotypic and genotypic
characterization. Patients’ symptoms and travelling data were
asked from the laboratory by phone. The presence of stx1, stx2,
eaeA, hlyA and saa genes was determinated by multiplex-PCR.
XbaI-PFGE profiles were analysed using BioNumerics 5.10
software. The strains were O:H serotyped by standard methods,
and the ability to ferment sorbitol was tested on SMAC plates
and in tubes containing 0.5% sorbitol.
Results
Of all detected 352 VTEC strains, 148 (42%) were non-O157 serotypes. Of these, 18 strains belonged to 12 different serotypes that
were associated with HUS. These 12 serotypes included O26:H11, O78:H-, O101:H-, O104:H4, O121:H19, O145:H28, O145:H-,
O174:H21, O178:H19, R:H4, R:H49 and OX182:H25 (Table). The median age of the HUS patients was 2 years (ranging from two weeks
to 66 years). Of all patients with HUS, 10 (55%) were female. All cases were domestically-acquired and sporadic (or family-related)
cases. All HUS-related non-O157 strains were sorbitol-fermenting. Among the non-O157 strains, 15 had stx2 only, 2 had stx1 only and
one strain had both stx1 and stx2 genes. In addition, 11 strains harboured eaeA, 14 strains had hlyA and 2 strains had saa gene. All the
strains except two O145:H28 strains in 1999 had a unique Xbal-PFGE profile and no clustering was detected within the other strains or
within a certain serotype.
Table: Number of VTEC O157 and non-O157 associated with HUS cases during 1996-2011 and characterisation of VTEC non-O157 strains linked with HUS in Finland.
Year
1996
No. of
confirmed No. of HUS cases
VTEC cases associated with
each year
O157 serotype
6
1
1997
1998
1999
61
43
38
6*
5
3
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
18
15
15
15
10
21
14
12
8
29
20
1
2
2
0
0
4
3
1
0
1
1
2011
27
3
Total
352
33
* including two deaths
No. of HUS cases
associated with
non-O157
non-O157
serotypes
serotype
2
O174:H21
R:H49
1
O101:H0
3
O145:H28
O145:H28
O145:H1
R:H4
1
O178:H19
0
1
O26:H11
0
0
1
O26:H11
0
0
1
O78:H4
O145:HO26:H11
O121:H19
OX182:H25
3
O121:H19
O121:H19
O104:H4
18
Virulence genes
(stx1, stx2, eaeA,
hlyA, saa )
stx2
stx2
stx2, hlyA
PFGE profile
O174a
R1
O101a
Fermentation
of sorbitol
+
+
+
Sex of
patient
female
male
male
Age of
patient
[yr]
66
33
1
stx2, eaeA, hlyA
stx2, eaeA, hlyA
stx2, eaeA, hlyA
stx2
stx1, stx2, hlyA, saa
O145a
O145a
O145b
Rd
O178a
+
+
+
+
+
female
female
female
female
female
1
1
1
15
2
feaces
feaces
feaces
feaces
feaces
Domestic
Domestic
Domestic
Domestic
Domestic
stx2,eaeA, hlyA
O26i
+
female
2
feaces
Domestic
stx2, eaeA, hlyA
O26L
+
male
1
feaces
Domestic
stx1, hlyA
stx2, eaeA, hlyA
stx2, eaeA, hlyA
stx2, eaeA, hlyA
stx1,eaeA, hlyA, saa
stx2,eaeA, hlyA
stx2,eaeA, hlyA
stx2
O78a
O145L
O26j
O121a
O182a
O121b
O121c
O104c
+
+
+
+
+
+
+
+
Conclusions
HUS was found in 51/352 (14%) of VTEC infections. It predominated in infections caused
by VTEC O157:H7/H- strains but approximately one third of the HUS cases were caused
by VTEC non-O157 strains. During the surveillance period, 12 different non-O157
serotypes with varying virulence gene profiles were associated with HUS, and VTEC
O78:H- was also found to be able to invade the bloodstream of a newborn baby.
Sample type
feaces
feaces
feaces
Origin
Domestic
Domestic
Domestic
male
<1
feaces and blood
male
4
feaces
male
4
feaces
female
<1
feaces
female
5
feaces
male
2
feaces
male
6
feaces
female
3
feaces
Median age 2 yr
Domestic
Domestic
Domestic
Domestic
Domestic
Domestic
Domestic
Domestic
Acknowledgements
The personnel of the Bacteriology Unit of
THL is gratefully acknowledged for the
skilful technical assistance in serotyping,
virulence genes determination and PFGE
analysis of the studied strains.
Contact: taru.lienemann@ thl.fi or
[email protected]