Monday, February 20, 2012

E. coli O26 infections linked to Clover Sprouts

Raw sprouts are responsible for another outbreak of foodborne illness and at least the fourth outbreak linked to the same restaurant chain, Jimmy Johns. In this latest case, there are 12 people infected with STEC O26 (CDC and AP link below). 

After the last outbreak linked to the restaurant chain in late 2010 where close to 120 people became ill with Salmonella, the chain switched from alfalfa sprouts to clover sprouts. But sprouts are sprouts – they are a higher risk food item in that it can be difficult to remove organisms such as Salmonella and E.coli from the seeds, and the process that allows the seed to sprout also may allow the organism to grow. Now, it appears the chain will drop sprouts from its menu ( 

Tainted sprouts again linked to Jimmy John’s, outbreak is fourth linked to restaurantBy Associated Press, Published: February 15

WASHINGTON — Raw sprouts from the sandwich chain Jimmy John’s have been linked to an outbreak of foodborne illness — again.

The federal Centers for Disease Control and Prevention said Wednesday that 12 cases of E. coli poisoning in five states are linked to raw clover sprouts eaten at Jimmy John’s restaurants. The outbreak comes a year after raw alfalfa sprouts from one of the chain’s suppliers were linked to 140 salmonella illnesses. Sprouts from the chain’s suppliers were also linked to a 2009 salmonella outbreak in several Midwestern states and were suspected in an E. coli outbreak in Boulder, Colo. in 2008.

Illinois-based Jimmy John’s declined to comment on the outbreak. After the salmonella outbreak a year ago, the company said it would switch from using alfalfa sprouts to using clover sprouts because they are easier to clean. But federal regulators warn against eating all raw sprouts, which are one of the most frequent perpetrators of foodborne illness.

Though they are often touted as a health food, sprouts need warm and humid conditions to grow, encouraging bacterial growth. Many restaurants have stopped serving them after multiple outbreaks, and the government recommends that the very young, elderly, pregnant and others with compromised immune systems stay away from raw sprouts completely. Fully cooked sprouts are safe to eat.

According to the CDC, there have been at least 30 outbreaks associated with raw or lightly cooked sprouts in the United States in the last 15 years and even more around the world, including a 1996 outbreak in Japan that sickened thousands of people with E. coli. Fenugreek sprout seeds from Egypt are thought to have caused a major outbreak of E. coli poisoning in Europe last year that killed more than 50 people.

Illnesses in the current outbreak were reported in Iowa, Missouri, Kansas, Arkansas and Wisconsin. The illnesses occurred between Dec. 25 and Jan. 15 and two of the victims were hospitalized.

In most sprout outbreaks the restaurant is not to blame for the contamination itself. Contamination usually happens when the seeds are grown or harvested and is often impossible to wash off.

Food safety lawyer Bill Marler has represented victims in the three previous sprout outbreaks potentially linked to Jimmy John’s. He has pushed the FDA to require warning labels on sprouts and praises restaurants that have taken them off the menu.

“You have to wonder what this company is thinking,” he said.

Investigation Announcement: Multistate Outbreak of Shiga Toxin-producing Escherichia coli O26 Infections Linked to Raw Clover Sprouts at Jimmy John's Restaurants Posted February 15, 2012 1:30 PM ET

· Read the Advice to Consumers »
· A total of 12 persons infected with the outbreak strain of STEC O26 have been reported from 5 states.
· The number of ill persons identified in each state is as follows: Iowa (5), Missouri (3), Kansas (2), Arkansas (1), and Wisconsin (1).
· Two ill persons have been hospitalized, and no deaths have been reported.
· Preliminary results of the epidemiologic and traceback investigations indicate eating raw clover sprouts at Jimmy John's restaurants is the likely cause of this outbreak.
· FDA's traceback investigation is ongoing. Traceback information on sprouts has identified a common lot of clover seeds used to grow clover sprouts served at Jimmy John's restaurant locations where ill persons ate.
Initial Announcement
CDC is collaborating with public health officials in multiple states and the U.S. Food and Drug Administration (FDA) to investigate a multistate outbreak of Shiga toxin-producing Escherichia coli serogroup O26 (STEC O26) infections likely linked with eating raw clover sprouts. Public health investigators are using DNA "fingerprints" of E. coli bacteria obtained through diagnostic testing with pulsed-field gel electrophoresis, or PFGE, to identify cases of illness that may be part of this outbreak. They are using data from PulseNet, the national subtyping network made up of state and local public health laboratories and federal food regulatory laboratories that performs molecular surveillance of foodborne infections.

The type of bacteria responsible for this outbreak are referred to as STEC. STEC bacteria are grouped by serogroups (e.g., O157 or O26). The STEC serogroup found most commonly in U.S. patients is E. coli O157. Other E. coli serogroups in the STEC group, including O26, are sometimes called "non-O157 STECs." Some types of STEC frequently cause severe disease, including bloody diarrhea and hemolytic uremic syndrome (HUS). Others, such as common strains of STEC O26, typically cause milder illness. Currently, there are limited public health surveillance data on the occurrence of non-O157 STECs, including STEC O26; therefore, STEC O26 infections may go undiagnosed or unreported. Because non-O157 STEC infections are more difficult to identify than STEC O157, many clinical laboratories do not test for them. The STEC O26 PFGE pattern in this outbreak has rarely been seen before in PulseNet.

Initial Case Count

A total of 12 persons infected with the outbreak strain of STEC O26 have been reported from 5 states. The number of ill persons identified in each state is as follows: Iowa (5), Missouri (3), Kansas (2), Arkansas (1), and Wisconsin (1). Among persons for whom information is available, illness onset dates range from December 25, 2011 to January 15, 2012. Ill persons range in age from 9 years to 49 years old, with a median age of 25 years old. One hundred percent of ill persons are female. Among the 12 ill persons, 2 (17%) were hospitalized. None have developed HUS, and no deaths have been reported.
The outbreak can be visually described with a chart showing the number of people who became ill each day. This chart is called an epi curve. Illnesses that occurred after January 27, 2012, might not be reported yet due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 3 weeks. All epi curves for this investigation are available on the epi curve page. Please see the E. coli Outbreak Investigations: Timeline for Reporting Cases for more details.
Initial Investigation Information

Epidemiologic and traceback investigations conducted by officials in local, state, and federal public health, agriculture, and regulatory agencies have linked this outbreak to eating raw clover sprouts. Among the 11 ill persons with information available, 10 (91%) reported eating at a Jimmy John's sandwich restaurant in the 7 days preceding illness. Ill persons reported eating at 9 different locations of Jimmy John's restaurants in 4 states in the week before becoming ill. One location was identified where more than one ill person reported eating in the week before becoming ill. Among the 10 ill persons who reported eating at a Jimmy John's restaurant location, 8 (80%) reported eating a sandwich containing sprouts, and 9 (90%) reported eating a sandwich containing lettuce. Currently, no other common grocery stores or restaurants are associated with illnesses.

FDA's traceback investigation is ongoing. Preliminary traceback information has identified a common lot of clover seeds used to grow clover sprouts served at Jimmy John's restaurant locations where ill persons ate. FDA and states conducted a traceback that identified two separate sprouting facilities; both used the same lot of seed to grow clover sprouts served at these Jimmy John's restaurant locations. On February 10, 2012, the seed supplier initiated notification of sprouting facilities that received this lot of clover seed to stop using it. Investigations are ongoing to identify other locations that may have sold clover sprouts grown from this seed lot.

This investigation is ongoing, but preliminary results of the epidemiologic and traceback investigations indicate eating raw clover sprouts at Jimmy John's restaurants is the likely cause of this outbreak. CDC and state and local public health partners are continuing laboratory surveillance through PulseNet to identify additional ill persons and to interview ill persons about foods eaten before becoming ill. FDA is continuing to work closely with CDC and state partners during this investigation. CDC will update the public on the progress of this investigation as information becomes available.

Based on previous outbreaks associated with sprouts, investigation findings have demonstrated that sprout seeds might become contaminated in several ways. They could be grown with contaminated water or improperly composted manure fertilizer. They could be contaminated with feces from domestic or wild animals, or with runoff from animal production facilities, or by improperly cleaned growing or processing equipment. Seeds also might become contaminated during harvesting, distribution, or storage. Many clover seeds are produced for agricultural use, so they might not be processed, handled, and stored as human food would. Conditions suitable for sprouting the seed also permit bacteria that might be present on seeds to grow and multiply rapidly. 

In 1999, FDA released guidance to help seed producers and sprout growers enhance the safety of their products. Specific measures recommended in the guidelines include a seed disinfection step and microbiologic tests of water that has been used to grow each lot of sprouts. The microbiologic tests currently recommended under this guidance would not identify the presence of STEC O26.

Initial Laboratory Testing Information

Preliminary results indicate that this strain of E. coli produces Shiga toxin type 1 and does not produce Shiga toxin type 2.


  1. Thanks for this great blog post. I do a lot of Sprouting Seeds and i never really came across having E Coli. This was a very interesting article. Good information and insights...

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