Pathogenic Escherichia coli, e coli typical

The article brings information about the beneficial and pathogenic effects of E. coli on human health. From the point of view of the foodborne infections, the most important group are the Enterohaemorrhagic E. coli. products at risk include not only raw or undercooked meat and milk but also vegetables, fruits and sprouted seeds. Prevention of diseases that are caused by the bacteria enteropathogenic E. coli (EPKP), lies in the preventive measures and the observance of the principles of good manufacturing and hygienic practices.

What bacterium is as versatile as escherichia coli escherichia coli (E. coli). It can easily take genes from other species of bacteria, in particular Enterobacteriaceae, and thereby adapt to external conditions. Bacteria of this species are usually found in the gut of humans and warm-blooded animals. Most strains that typical E. coli and E. coli is not pathogenic, some of them positively contribute to the process of digestion and the formation of vitamins, for example B12, K1 and K2. Some strains are even used as probiotics, for example, if you have problems with digestion; among properties, which has a typical E. coli include barrier penetration and expansion of pathogenic bacteria. However, in the case of a weakened immune system can reach to the multiplication and dissemination of Escherichia coli from the gastrointestinal tract lower body. Such action of bacteria causing urinary tract infections and (rarely) sepsis. In such cases, the tests show an increased total number of E. coli (norm: up to 10, 8-th degree CFU/g, increased amount: 10 to 10 degree CFU/g).

Distribution and characteristics of pathogenic Escherichia coli

Only a small proportion of strains of E. coli cause gastrointestinal diseases (respectively, increasing the number of bacteria). These strains penetrate the intestine with the food or water (alimentary way). In accordance with their pathogenic effects on the intestine there are 6 major groups.

1. EPEC – enteropathogenic E. coli, or dyspeptic. Earlier it was a frequent cause of diarrhoea in infants and young children. At present, however, in developed countries, is rare.
2. EIEC – enteroinvasive E. coli. Can cause disease, the course resembles bacterial dysentery.
3. ETEC – enterotoxigenic E. coli. Causes diarrhea in children and adults; widespread, especially in developing countries with warm climates. The disease is often referred to as traveller's diarrhoea.
4. A/EEC – attaching and effacing E. coli (yet has no specific definition in Russian). Causes of the disease, especially in cattle, and is pathogenic only in rare cases.
5. EAEC – enteroaggregative E. Coli. Causes prolonged diarrhea, especially in children; the disease is usually not accompanied by fever.
6. EHEC – Enterohaemorrhagic E. Coli. Creates toxins, such as toxins produced by the bacteria Shigella dysenteriae type 1, also referred to as verotoxins or Shiga (STX). From the name of the toxins occurs another name for this group of E. coli called STEC (E. coli shigatoxigenic).

E. coli and diseases

The most famous representative of the group is EHEC serotype O157:H7, but the incidence in Europe are also involved and other serotypes: Q26, Q91, O103, O145 and O111. Some strains of EHEC/STEC, produce toxins, even a small increase in the degree, can cause serious foodborne illness, particularly in young children. Clinical symptoms include bloody diarrhoea (haemorrhagic colitis; along with the loose stools can stab in the gut), which can move to the stage of acute renal failure (HUS – hemolytic uremic syndrome), causekidney damage or even death of the sick person.

The significance of EHEC/STEC infection and resources

The importance of this disease were in the area of public health described in the 80-ies of the last century, after several major outbreaks in the United States. This disease is transmitted to humans primarily through consumption of contaminated food or water. To a lesser extent there is also direct transmission from animal to human, for example, when visiting a farm or zoo, with direct contact with animals also can be transferred from person to person (fecal-oral route). This reservoir of E. coli are mainly ruminants, farmed as food animals, but wild. Therefore, risk is the consumption of improperly prepared animal products, particularly undercooked beef, milk, or dairy products.

Less frequently cited sources include raw fruits and vegetables. These include: unpasteurized juice, raw salads and cut fruits or vegetables, sprouted seeds and shoots of plants. Contamination usually occurs on soils that are fed organic fertilizers.

Another source of infection may be raw water from uncontrolled sources. The disease can also occur after swimming in natural lakes and ponds, because bacteria can survive a long time in the mud and sediments.

Growth conditions EHEC/STEC

E. coli belongs to facultative anaerobic bacteria, can grow at temperatures in the range of 7-50°C, the optimum temperature is 37°C. Some strains of EHEC/STEC can spread in an acidic environment, even to a pH of 4.4. Bacteria, however, are utilized for pasteurization or sterilization (i.e. high temperatures).

Epidemiology

From an epidemiological point of view, the disease caused by E. coli usually appear as sporadic cases, which have rarely managed to trace the source of infection. One of the biggest epidemics described in Japan in 1996, was caused by EHEC/STEC serotype O157:H7 producing Shiga. It was 9451 cases of children who ate in the school cafeteria. The source of infection was sprouted seeds of radish.

In the XXI century in the countries of the European Union had been 3 outbreaks of epidemics. They all occurred in 2011. From January to may 2011 in the UK was reported about 50 cases of diseases caused by EHEC/STEC, was identical in all patients (serotype O157), and was characterized by the production of both toxins (STX1 and STX2). Among the victims was dominated by women (67%). The origin and source of infection still unclear.

In may of the same year in Germany near Hamburg was the largest epidemic caused by EHEC/STEC in Europe. The victims were adults, especially women (71%) with good eating habits (frequent consumption of vegetables and salads). Ill more than 4,000 people, over 50 of them died from disease. Many people who survived the disease, now face health complications such as kidney failure and neurological and psychological symptoms. The causative agent of the disease is characterized as EHEC/STEC serotype O104:H4. The source of infection was sprouted seeds and shoots of plants used to decorate salads in restaurants, but also common in commercial networks and markets (seeds of fenugreek (Trigonella foenum-graeceum) from Egypt).

Another outbreak occurred in June 2011 in the North of France, where, after consumption of insufficiently cooked hamburgers 7 children were hospitalized with a syndrome developed gemorragicescom-uremic syndrome. The causative agent was identified as EHEC/STEC O157.

Preventive measure

Like other foodborne infections, the disease caused by EHEC/STEC, it is possible to prevent the consistent observance of rules of hygiene. Preventive measures should be applied on farm animals by reducing the incidence of pathogenic bacteria in animals and thus prevent their further spread into the environment.

The key problem is, for example, fertilization of the soil. The use of manure in growing vegetables and fruits, which come into direct contact with the soil, is one of the major risk factors.

An effective measure against the spread of EHEC/STEC is the corresponding heat treatment of raw materials and foodstuffs, particularly beef and milk. Consumption of raw milk and raw milk products is another risk factor.

Vegetables and fruits must be thoroughly washed under running tap water.

In recent years, became popular consumption of germinated seeds, not only because of their nutritional value but also for their interesting appearance and taste. The problem, however, is the contamination of seeds by pathogenic bacteria such as Salmonella, L. monocytogenes or EHEC/STEC. The seeds can be contaminated during harvesting, storage and transportation. In the germination process of the pathogenic bacteria multiply rapidly (high humidity and temperature, sufficient amount of nutrients).

The most common questions about E. coli

How can a person infected with E. coli?

People become infected mainly by oral administration, for example,contaminated water, food or by direct contact with an infected person or animal. To become infected quite easily, because in the case of EHEC O157:H7 induction dose is only 10-100 microbes.

Studies that were carried out in Germany showed that the transmission path associated with age. In infants and young children up to 3 years greatest risk is direct contact with animals, persons suffering from diarrhoea, playing in the sandbox and consumption of raw milk. Threat is also swimming in swimming pools contaminated by the feces or in natural bodies of water contaminated by manure from cultivated land. In children older than 9 and adults often have a choice of foodborne infection.

What foods E. coli occurs?

The main sources of E. coli are considered ruminants, especially cattle, sheep and goats, and fowl. Infected animals do not get sick themselves, but secrete pathogen with droppings. E. coli may also be contained in soil and water, because bacteria are able to survive in such conditions for several weeks. From livestock bacteria can get into food, for example, at slaughter, during milking. E. coli not detected in heat-treated foods from animals, such as:

• raw milk,
• raw dairy products (cheese),
• raw or undercooked meat,
• not heat-treated meat products.

Through contaminated water and contact with feces can be contaminated vegetable products (fruits, vegetables). Bacteria can also get into plants. Eating raw vegetables can be a reason for the emergence of Escherichia coli.

Infection can also occur after drinking unpasteurized Apple juice, raw greens and sprouts.

In addition, the infection can spread and the so-called cross-contamination. The bacteria can be transmitted by direct contact or products via hands, utensils, and other surfaces. Cross contamination, for example, when you use the same knife for raw meat and then for a salad.

How is it possible to kill bacteria?

E. coli is destroyed in the process of cooking, baking, pasteurization, provided that the product is exposed to a temperature of at least 70°C, at least for 2 minutes. Unlike other bacteria, these bacteria are highly resistant to acidity, cooling, drying and high salt concentration. Even freezing cannot reliably destroy them.

Under what conditions do bacteria spread?

E. coli can reproduce at the temperature 7-50°C if the soil has a sufficient supply of nutrients and water, and not exposed to other substances (acids, salts). Optimum temperature is 37°C, bacteria multiply faster when the temperature is close to this figure.

How to protect yourself from E. coli infections caused by the food?

The most effective measures to prevent infection with E. coli:

1. Raw milk should be boiled before consumption; pasteurized and sterilized milk is considered to be safe.
2. Before preparing food and after contact with raw meat wash hands thoroughly with warm water and soap and dry them thoroughly.
3. Raw meat should be stored and handled separately from other food (when preparing to use the other cutting Board, utensils, Cutlery).
4. Surfaces and objects after a contact with raw meat or water from defrosting must be immediately thoroughly cleaned and dried.
5. Tablecloths and towels after preparing raw meat should be washed in water at a temperature of at least 60°C.
6. Raw vegetables and fruits before eating should be thoroughly washed.

How to protect yourself from E. coli infection, caused by contact?

To avoid infection with E. coli via direct contact with infected animals should adhere to the following rules of hygiene:

1. To look after young children while interacting with animals.
2. After contact with animals or soil and before eating food and drinks, it is necessary to wash hands thoroughly with soap and water.
3. Food and drinks should be consumed only off the premises with the animals.