Published Date: 2006-03-04 23:50:00
Subject: PRO/AH/EDR> E. coli VTEC non-O157, minced beef - Norway
Archive Number: 20060304.0680
E. COLI VTEC NON-O157, MINCED BEEF - NORWAY
A ProMED-mail post
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International Society for Infectious Diseases
Date: Thu, 2 Mar 2006
From: ProMED-mail <email@example.com>
Source: Eurosurveillance [edited]
On 20 and 21 Feb 2006, 6 cases of diarrhea-associated hemolytic uraemic
syndrome (HUS) were reported to Nasjonalt folkehelseinstitutt (Norwegian
Institute of Public Health, NIPH). 4 cases were reported by a pediatrician
in a university hospital in Oslo and the other 2 cases were diagnosed in
Bergen. On 27 Feb 2006, a 7th case of HUS was reported. The number of cases
of domestic enterohemorrhagic _Escherichia coli_ (EHEC) [other
terminologies are VTEC for Vero-toxin producing _E. coli_ and STEC for
Shiga toxin producing _E. coli_) infection reported annually has been about
10 in recent years, mostly sporadic cases of bloody diarrhea, only rarely
complicated with HUS (1). HUS is not notifiable in Norway.
The 7 patients (3 boys and 4 girls) were between 2 and 8 years old, median
age 5 years. 6 children had bloody diarrhea before they developed HUS. 5 of
the children are still in hospital, and 2 have been discharged. 5 patients
were from counties in central Norway and 2 patients from the west coast.
On 22 Feb 2006, the parents of the 1st 6 HUS patients were interviewed,
using a standardized trawling questionnaire. Based on the responses, a more
specific questionnaire listing 26 food items was developed for a case
control study. We included specific questions on the brands of meat and
dairy products consumed, and the shops where they were bought. 3 age- and
sex-matched controls were selected for each case from the municipal
population registers in the areas where the patients lived. We asked the
parents about food consumed by their children in the week before onset of
diarrheal symptoms. The matched controls answered these questions for the
All 6 patients and 14 out of 18 controls had eaten minced beef. The case
control study strongly pointed to the consumption of a specific brand of
minced meat (brand A) as the likely source of the HUS outbreak. Minced beef
of brand A had been consumed by all patients (100 per cent) and by only 6
controls (33 per cent). Thus, the matched odds ratio was infinity.
Parents of the first 6 patients indicated that they had purchased fresh
minced beef between late Dec 2005 and mid-Feb 2006. This information was
immediately communicated to the Norwegian Food Safety Authority. An
Enter-net (<http://www.hpa.org.uk/hpa/inter/enter-net_menu.htm>) urgent
enquiry to detect any cases outside Norway was sent out on 22 Feb 2006, but
no other country reported cases that could be linked to this outbreak.
Initial isolation of _E. coli_ from stool samples from the HUS cases was
attempted at the primary hospital laboratories, but all results were
negative. However, many of the primary hospital laboratories test for _E.
coli_ O157, but not for other serogroups. Further investigation at the
national reference laboratory for enteropathogenic bacteria isolated _E.
coli_ serogroup O103 from 2 patients' samples. Both isolates contained the
eae gene (intimin-encoding), while only 1 isolate contained shiga-like
toxin 2 (Stx2). One serum sample from a 3rd patient showed a high antibody
titer (2560) against _E. coli_ O103. Further characterization of patient
isolates and serology is ongoing.
Environmental investigation and control measures:
Leftover minced beef and other food items still stored in the patients�
homes were collected and batch numbers were checked. Producer A is a
national meat manufacturer producing meat exclusively from Norwegian
cattle, with several slaughterhouses in different parts of Norway.
On 24 Feb 2006, product tracing at producer A showed that the incriminated
minced beef had probably been produced by one specific slaughterhouse. A
thorough environmental inspection took place and minced meat production was
put on hold. The same day, producer A issued a recall of 3 types of fresh
and frozen minced beef labelled N103' an authorisation number indicating
that the meat had been produced at the suspected slaughterhouse. The recall
was announced widely through mass media. Consumers were advised to return
the suspect minced beef packages to the supermarket or to destroy them. At
the same time, recommendations on good kitchen hygiene and thorough cooking
of minced meat were given. There is no indication that the product has been
exported to any other country.
Health authorities advised the public to contact a physician if they
experienced symptoms of bloody diarrhea. Test results of the leftover
minced beef collected from the implicated households are pending.
Preliminary samples from the producer have been negative.
The fact that all the EHEC cases reported in this outbreak developed HUS
may indicate that there is substantial underreporting of non-O157 EHEC
infections due to the current laboratory methods used by many laboratories.
The importance of testing for non-O157 EHEC strains has also been raised by
others (2). Discussions to implement pediatric HUS surveillance in Norway
are warranted, reflecting experiences from other European countries.
1. Grahek-Ogden D, Lassen J, Nygard K. EHEC-infeksjoner i Norge 1995-2004.
MSIS-rapport 2005; 33(38): 1. [in Norwegian].
2. Kraigher A, Seme K, Krt-Lah A, Fisher A. Fatal case of HUS after VTEC E.
coli O145 infection in Slovenia highlights importance of testing for this
rare strain. Eurosurveillance 2005; 10(9): 050915.
[Authors: Schimmer B(<firstname.lastname@example.org>), Eriksen H-M, Nygard K, et al]
[This report is an excellent example of how to investigate a VTEC outbreak.
A map showing the localities of Oslo and Bergen in southern Norway can be
found at <http://www.lonelyplanet.com/mapshells/europe/norway/norway.htm>.
Although much attention has been paid to O157:H7 strains of _E. coli_ that
(by virtue of toxin production) cause enterohemorrhagic disease with or
without hemolytic-uremic syndrome, other serotypes of _E. coli_ have been
associated with this illness as well.
_E. coli_ strains can be grouped by the presence of their O (somatic) and H
(flagellar) antigens, hence O157:H7. The toxins produced are generally one
or 2 Shiga toxins (stx1 and stx 2) as well as eae, a protein intimin that
is responsible for attachment of the organism and mucosal effacing lesions
and other virulence factors including E-hly, espA, etp and katP.
Other _E. coli_ serogroups that have been associated with VTEC disease
include motile ones such as O26:H11 and O104:H21 and nonmotile ones such as
O111:NM (or H-). Such non-O157 isolates can be obtained from sheep and
cattle and although they cause as many as 30 per cent of outbreaks of VTEC
(1), appear to be somewhat less (or at least more variably) virulent in a
variety of in vivo and in vitro assays (2-4). In analyzing the genetic and
phenotypic profiles of non-O157 groups, it has been found that they belong
to their own lineages and have unique profiles of virulence traits
different from O157 (5). The serogroups appearing to be most prominent are
O26, O111, O128, and O103 (6), the latter serotype being the implicated
strain in this outbreak.
If a laboratory is using sorbitol-MacConkey (sMAC) plates to identify VTEC
by virtue of O157's inability to ferment sorbitol, the non-O157 strains
will be missed. In a 3 year pediatric study from the University of
Washington, USA (7), 1851 stool samples were processed for sorbitol
fermentation as well as toxin production by EIA, and 28 strains of O157
were found along with O103 (4 strains), O118 (2 strains), O111 (2 strains),
and 3 other strains.
Clinically, the O157 infections had a higher frequency of bloody stools,
fecal leukocytes, and abdominal pain with shorter symptom duration. 5 (18
per cent) of O157 infections developed HUS; none of the non-O157 strains
did. Since toxin assay did not identify all O157 strains found on sMAC
plates, the investigators did not advocate performing toxin assay alone.
Non-O157 can produce hemolytic-uremic syndrome, as demonstrated by a
cluster of O121 cases associated with a lake in Connecticut, USA (8).
Since toxin assays are not uniformly performed in many areas, and most
cases do not produce HUS, it is likely that cases due to non-O157 strains
are being missed. How frequent this phenomenon will become over time is
1. Hussain HS, Omaye ST. Introduction to the food safety concerns of
verotoxin-producing Escherichia coli. Exp Biol Med 2003; 228: 331-2.
2. Blanco J, Blanco M, Blanco JE, et al. Verotoxin-producing Escherichia
coli in Spain:prevalence, serotypes, and virulence genes of O157:H7 and
non-O157 VTEC in ruminants, raw beef products and humans. Exp Biol Med
2003; 228: 345-51.
3. Law D, Kelly J. Use of heme and hemoglobin by Escherichia coli O157 and
other Shiga-toxin-producing E. coli serogroups. Infect Immun 1995; 63: 700-2.
4. Tzipori S, Wachsmuth KI, Smithers J, Jackson C. Studies in gontobiotic
piglets on non-O157:H7 Escherichia coli serotypes isolated from patients
with hemorrhagic colitis. Gastroenterology 1988; 94: 590-7.
5. Schmidt H, Geitz C, Tarr PI, et al. Non-O157:H7 pathogenic Shiga-toxin
producing Escherichia coli: phenotypic and genetic profiling of virulence
traints and evidence for clonality. J Infect Dis 1999; 179: 115-23.
6. Bettelheim KA. Role of non-O157 VTEC. Symp Ser Soc Appl Microbiol 2000;
7. Klein EJ, Stapp JR, Calusen CR, et al. Shiga toxin-producing Escherichia
coli in children with diarrhea:a prospective point-of-care study. J Pediatr
2002; 141: 172-7.
8. McCarthy TA, Barrett NL, Hadler JL, et al. Hemolytic-uremic syndrome and
Escherichia coli O121 at a lake in Connecticut, 1999. Pediatrics 2001; 108: