E. coli O157, spinach - USA (multistate)(05)

International Society for Infectious Diseases
<http://www.isid.org>

Source: FDA.gov [edited]
< http://www.fda.gov/bbs/topics/NEWS/2006/NEW01457.html>

Case Reports:
To date, 114 cases of illness due to _E. coli_ [O157:H7] infection
have been reported to CDC, including 18 cases of Hemolytic Uremic
Syndrome (HUS), 60 hospitalizations, and 1 death. Illnesses continue
to be reported to CDC. This is considered to be an ongoing investigation.

States Affected:
There are now 21 confirmed states: California, Connecticut, Idaho,
Illinois, Indiana, Kentucky, Maine, Michigan, Minnesota, Nebraska,
Nevada, New Mexico, New York, Ohio, Oregon, Pennsylvania, Utah,
Virginia, Washington, Wisconsin, and Wyoming.

Consumer Advice:
FDA advises consumers not to eat fresh spinach or fresh
spinach-containing products until further notice.

If individuals believe they may have experienced symptoms of illness
after consuming fresh spinach or fresh spinach-containing products,
FDA recommends that they seek medical advice.

2 Recalls:
On 17 Sep 2006, River Ranch, of Salinas, California, announced a
recall of packages of spring mix containing spinach. River Ranch
obtained bulk spring mix containing spinach from Natural Selections.
The following brands are involved: Fresh N' Easy Spring Mix and
Hy-Vee Spring mix containing baby spinach, distributed to retailers
in Texas, Iowa and New Mexico. Product was packed in 5-oz. bags and
5-oz. plastic trays. Products that do not contain spinach are not
part of this recall.

On 15 Sep 2006, Natural Selections Foods, LLC, of San Juan Bautista,
California, announced a recall of all of its products containing
spinach in all brands they pack with "Best if Used by Dates" of 17
Aug 2006 through 1 Oct 2006. These products include spinach and any
salad with spinach in a blend, both retail and food service products.
Products that do not contain spinach are not part of this recall. The
Natural Selections Foods LLC brands recalled can be found on the
previous posts.

Another recall is announced in this posting related to a company
that received its spinach from Natural Selections.

Illinois and Nebraska are new in this posting with 12 more cases and
2 more cases of hemolytic uremic syndrome compared to ProMED's previous post.

A selective agar is used to identify _E. coli_ O157:H7 in clinical
specimens and food. Unlike a typical _E. coli_, isolates of O157:H7
do not ferment sorbitol but do, like the usual _E. coli_, ferment
lactose. Sorbitol-MacConkey agar (MacConkey agar contains lactose)
has been used extensively to isolate this organism from clinical specimens.
Sorbitol-positive isolates of _E. coli_ O157 present a significant
problem in screening stools for this pathogen, as the lack of
sorbitol fermenting is usually a prime criterion.  If clinical
suspicion exists, potential isolates should be sent to reference
laboratories.  Toxin production can be detected by immunoblot, and
O157 antigen can be detected by ELISA.  Not only do these isolates
ferment sorbitol, but they also are tellurite-susceptible (1) and
will not be isolated on cefixime-tellurite Sorbitol-MacConkey agar, a
selective medium for the usual _E. coli_ O157.

Although first recognized in Germany in 1988 (1),
sorbitol-fermenting, verotoxigenic _E. coli _O157 was thought to be
restricted to continental Europe (2) until an isolation in Australia
in 2002. The first isolation in the UK was also reported in 2002.

E. coli_ strains can be grouped by the presence of their O (somatic)
and H (flagellar) antigens, hence O157:H7.  The verotoxin-producing
E. coli (VTEC) -- the prototype is O157:H7 -- toxins are generally
one or 2 Shiga toxins (stx1 and stx 2) as well as eae, a protein
intimin that is responsible for intimate 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 causing as much as 30
percent of outbreaks of VTEC (3), appear to be somewhat less or at
least more variable in virulence in a variety of in vivo and in vitro
assays (4-5).  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 (7). The serogroups appearing to be most prominent are O26,
O111, O128, and O103 (8).

If a laboratory is using sorbitol-MacConkey (sMAC) plates to identify
VTEC by virtue of O157's ability to ferment sorbitol, the non-O157
strains will be missed.  In a 3-year pediatric study from the
University of Washington, USA (9), 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. Five (18 percent) O157 infections developed
hemolytic-uremic syndrome; 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 (10).

1. Karch H, Bielaszewska M. Sorbitol-fermenting shiga toxin-producing
_Escherichia coli_ O157:H- strains: epidemiology, phenotypic and
molecular characteristics, and microbiological diagnosis. J Clin
Microbiol 2001;39: 2043-9.

2. Bettleheim KA, Whipp M, Djordjevic SP, Ramachandran V. First
isolation outside Europe of sorbitol-fermenting verocytotoxigenic
_Escherichia coli_ (VTEC) belonging to O group O157. J Med Microbiol
2002; 51: 713-4.

3.  Hussain HS, Omaye ST. Introduction to the food safety concerns of
verotoxin-producing Escherichia coli. Exp Biol Med 2003;228:331-32.

4.  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.

5.  Law D, Kelly J. Use of heme and hemoglobin by Escherichia coli
O157 and other Shiga-toxin-producing E. coli serogroups. Infect Immun
1995;63:700-702.

6.  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;94:590-97.

7.  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 199;179:115-23.

8.  Bettelheim KA. Role of non-O157 VTEC. Symp Ser Soc Appl Microbiol
2000; (29):38S-50S.

9.  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;141:172-77.

10.  McCarthy TA, Barrett NL, Hadler JL, et al. Hemolytic-uremic
syndrome and Escherichia coli O121 at a lake in Connecticut, 1999.
Pediatrics 2001;108:E59.