Bacterial pathogens have been reported on fresh cucumbers and other vegetables used for commercial fermentation. The Food and Drug Administration currently has a 5-log reduction standard for?E. coli?O157:H7 and other vegetative pathogens in acidified pickle products. For fermented vegetables, which are acid foods, there is little data documenting the conditions needed to kill acid resistant pathogens. To address this knowledge gap, we obtained 10 different cucumber fermentation brines at different stages of fermentation from 5 domestic commercial plants. Cucumber brines were used to represent vegetable fermentations because cabbage and other vegetables may have inhibitory compounds that may affect survival. The 5-log reduction times for?E. coli?O157:H7 strains in the commercial brines were found to be positively correlated with brine pH, and ranged from 3 to 24 d for pH values of 3.2 to 4.6, respectively. In a laboratory cucumber juice medium that had been previously fermented with?Lactobacillus plantarum?or?Leuconostoc mesenteroides?(pH 3.9), a 5-log reduction was achieved within 1 to 16 d depending on pH, acid concentration, and temperature. During competitive growth at 30 °C in the presence of?L. plantarum?or?L. mesenteroides?in cucumber juice,?E. coli?O157:H7 cell numbers were reduced to below the level of detection within 2 to 3 d. These data may be used to aid manufacturers of fermented vegetable products determine safe production practices based on fermentation pH and temperature. PRACTICAL APPLICATION:? Disease causing strains of the bacterium?E. coli?may be present on fresh vegetables. Our investigation determined the time needed to kill?E. coli?in cucumber fermentation brines and how?E. coli?strains are killed in competition with naturally present lactic acid bacteria. Our results showed how brine pH and other brine conditions affected the killing of?E. coli?strains. These data can be used by producers of fermented vegetable products to help assure consumer safety.
E. coli bacteria: what are they, where did they come from, and why are some so dangerous?
Escherichia coli (E. coli) are members of a large group of bacterial germs that inhabit the intestinal tract of humans and other warm-blooded animals (mammals, birds). Newborns have a sterile alimentary tract, which within two days becomes colonized with E. coli.
More than 700 serotypes of E. coli have been identified. The “O” and “H” antigens on their bodies and flagella distinguish the different E. coli serotypes, respectively. The E. coli serotypes that are responsible for the numerous reports of outbreaks traced to the consumption of contaminated foods and beverages are those that produce Shiga toxin (Stx), so called because the toxin is virtually identical to that produced by another bacteria known as Shigella dysenteria type 1 (that also causes bloody diarrhea and hemolytic uremic syndrome HUS in emerging countries like Bangladesh) (Griffin & Tauxe, 1991, p. 60, 73). The best-known and most notorious Stx-producing E. coli is E. coli O157:H7. It is important to remember that most kinds of E. coli bacteria do not cause disease in humans, indeed, some are beneficial, and some cause infections other than gastrointestinal infections, such urinary tract infections. This section deals specifically with Stx-producing E. coli, including specifically E. coli O157:H7.
Shiga toxin is one of the most potent toxins known to man, so much so that the Centers for Disease Control and Prevention (CDC) lists it as a potential bioterrorist agent (CDC, n.d.). It seems likely that DNA from Shiga toxin-producing Shigella bacteria was transferred by a bacteriophage (a virus that infects bacteria) to otherwise harmless E. coli bacteria, thereby providing them with the genetic material to produce Shiga toxin.
Although E. coli O157:H7 is responsible for the majority of human illnesses attributed to E. coli, there are additional Stx-producing E. coli (e.g., E. coli O121:H19) that can also cause hemorrhagic colitis and post-diarrheal hemolytic uremic syndrome (D+HUS). HUS is a syndrome that is defined by the trilogy of hemolytic anemia (destruction of red blood cells), thrombocytopenia (low platelet count), and acute kidney failure.
Stx-producing E. coli organisms have several characteristics that make them so dangerous. They are hardy organisms that can survive several weeks on surfaces such as counter tops, and up to a year in some materials like compost. They have a very low infectious dose meaning that only a relatively small number of bacteria (fewer than 50) are needed “to set-up housekeeping” in a victim’s intestinal tract and cause infection.
The Centers for Disease Control and Prevention (CDC) estimates that every year at least 2000 Americans are hospitalized, and about 60 die as a direct result of E. coli infection and its complications. A recent study estimated the annual cost of E. coli O157:H7 illnesses to be $405 million (in 2003 dollars), which included $370 million for premature deaths, $30 million for medical care, and $5 million for lost productivity (Frenzen, Drake, and Angulo, 2005).
E.coli in Cucumbers
A major news story over the weekend concerned death and serious illness in Germany by an infection with the bacteria E.coli ) O157, allegedly from imported cucumbers.
Escherichia coli (E.coli) are common bacteria that live in the intestines of warm-blooded animals. Some strains of E.coli do not cause any ill-effects but some, like O157, can cause illness. This can range from mild diarrhoea to death. The infective dose is very low meaning that only a few bacteria can cause infection.
Infection can occur from consuming food or water that has been contaminated by faeces from infected animals or through contact with them e.g. on farms and premises with animals open to the public.
According to the Food Standards Agency there is no evidence that cucumbers from the alleged sources have been distributed to the U.K.
However, we wish to reiterate the importance of thorough hand washing before eating and after contact with animals. It is also good practice to wash fruit and vegetables before eating.
Germany’s federal agriculture minister conceded Tuesday that “Spanish cucumbers are not the cause of the E. coli outbreak,” according to the Guardian. Germany is now scrambling to find out the real source of the outbreak.
Spain said it was considering suing German officials for blaming its cucumbers for the E. coli outbreak, and for the damage it has likely already done to its food export and farm business, Reuters reported. Spanish farmers have said they are losing around $286m per week in lost sales.
The number dead has now risen to 16 people, and the number sickened 1,500 in Germany, Sweden and other countries. 365 new cases were also reported on Wednesday. The Robert Koch Institute, Germany’s disease control center, said one quarter of the latest cases involved a serious complication called hemolyti-uremic syndrome, which affects the blood and kidneys, according to al-Jazeera.
E. coli cucumber scare: Cases likely to increase
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The Andalucian agriculture minister was keen to show her confidence in the region’s cucumbers
A deadly E. coli outbreak in Europe is expected to worsen in coming days, a senior German scientist has said.
Fourteen people have died in Germany and one woman has now died in Sweden after a trip to Germany.
“We hope the number of cases will go down but we fear it will worsen,” said Oliver Grieve, of the University Medical Centre Schleswig-Holstein, where many victims are being treated.
It is thought cucumbers from Spain caused the outbreak.
But Spanish officials have refused to accept the blame, saying it is still unclear exactly when and where the vegetables were contaminated.
The president of Spain’s fruit and vegetable export federation has urged the government to deal with the outbreak, saying it was costing Spanish exporters $200m (£120m) a week.
Asked which countries had stopped buying Spanish produce, Jorge Brotons reportedly told a news conference: “Almost all Europe. There is a domino effect on all vegetables and fruits.”
Travel linkThe World Health Organization (WHO) has described the outbreak as “very large and very severe” and has urged countries to work together to find the source of contamination.
The Robert Koch Institute (RKI), Germany’s national disease institute, has confirmed 329 cases in the country – though some reports have mentioned as many as 1,200 cases.
How the cucumber crisis affects Europe
Germany Consumers told not to eat cucumbers, lettuces and raw tomatoes. 373 cases of E.coli confirmed; 14 deaths
Spain Top European cucumber producer – threatens to seek compensation from the European Union for lost vegetables sales
Russia Ban on all imports of cucumbers, tomatoes and fresh salad from Spain and Germany pending further notice
This mainly involves adequate hygiene to prevent contamination of food and person to person spread. It particularly applies to farms, abattoirs and those working in healthcare, nurseries and food provision.
Correct food preparation is also important:
• Washing of raw vegetables.
• Adequate cooking of meat especially beefburgers.
• Pasteurisation of dairy products.
Advice to the public from the HPA is:10
• Safe food preparation:
o Fully cook minced meat products like beefburgers or meat loaf so that they are coloured all the way through, and no blood runs from them.
o Keep cooked and uncooked meats separately; store uncooked meat on the bottom shelf of the fridge to avoid dripping raw meat juices on to other food.
o Never put cooked food back on a plate which has had fresh uncooked meat on it.
o Thoroughly wash all salads and vegetables that are to be eaten raw.
o Avoid eating and drinking unpasteurised milk and dairy products.
o Boil any drinking water if you are unsure of its source.
• Do not swim in water that may be contaminated.
o Thoroughly wash hands after using the toilet, handling raw meat, before meals and after contact with animals.
o Ensure children wash their hands with warm water and soap after contact with animals, particularly while on farm visits.
o If someone has E. coli infection, wash all dirty clothes, bedding and towels in the washing machine on the hottest cycle possible. Clean toilet seats, toilet bowls, flush handles, taps and wash hand basins after use, with detergent and hot water, followed by a household disinfectant.
o If you have E. coli infection you should not prepare food for others.
• Some sources suggest that ‘probiotics’ (e.g. certain strains of lactobacilli) may help prevent gastro-intestinal infections, because they colonize the gastrointestinal tract and theoretically prevent pathogenic organisms from infecting the gut.12