Clostridium botulinum. Pathogen botulism

In the world there are many different bacterial infections. All of them differ from each other by the mechanisms of infection, the course of the disease and other nuances. In this article I want to talk in detail about clostridium botulinum, the causative agent of such a disease as botulism.

About the disease

At the very beginning, you need to say a few words about the very disease that this bacterium causes. So, botulism is a severe food intoxication. It flows sharply, often at the same time affects the central nervous system, possibly the occurrence of paralysis. Has a fecal-oral route of transmission.

The origin of the name will be interesting. From Latin, botulism translates as sausage (botulus). And all because for the first time these pathogenic bacteria were found in this food (and also in the bodies of dead people who had previously eaten sausage). Most often this disease is associated with the consumption of salted and smoked fish, as well as hams.

A bit of history

For the first time clostridium botulinum - causative agent of botulism - was described in the distant 1896 by the scientist E. van Ermengem. It happened just at the time of the strongest outbreak of the disease. As already mentioned, this pathogenic microorganism was isolated specifically from ham, as well as from the bodies of people who ate it earlier. A little later it was found that the microorganism includes 8 serovars, which differ in the antigenic structure of toxins (they also form them). The most important are toxins, called A, B and E. However, it should be noted that all toxins can be neutralized exclusively by homologous serum.

Appearance

What does clostridium botulinum look like? So, the bacterium is a fairly large stick, the end of which is slightly rounded. Its approximate size is 4-9x0.6-1.0 μm. Throughout the body, it has approximately 35 flagella, peritrichrally located. It can form spores. A stick with a spore looks like a tennis racket.

Ideal conditions

What are the conditions for clostridium botulinum ideal? Thus, the optimum temperature for their growth is about 35 ° C. However, the bacterium can multiply in the temperature range from 10 to 55 ° C. The microorganism is best cultivated:

1. In the Kitt-Tarozzi environment. This is a special meat-peptone broth with the addition of liver, minced meat and glucose.
2. On meat and fish extracts.
3. Where there is a high concentration of animal protein.

Bacteria can also multiply in different environments. So, the most convenient is glucose-blood agar (in this case the bacteria resemble slices of lentils or cotton wool). However, they can multiply in a liquid medium. In this case, a uniform turbidity is formed, and after a time a specific precipitate falls on the bottom of the tube.

Spread

Where is the bacterium clostridium botulinum common? So, "stumble" on them can be almost anywhere. Most often for the habitat of clostridium choose the following places:

1. Intestine of fish, animals and even molluscs.
2. Soil (microorganisms go there together with feces).
3. Food products. Especially dangerous in this case for man are vegetable, mushroom, meat and fish dishes.

In the soil, spores survive better than the vegetative forms of the bacterium. Spores can withstand prolonged drying, freezing to -250 ° C, boiling from one to six hours. And even in a solution of phenol (5%), spores of bacteria can remain viable for up to 1 day. At boiling, the toxin breaks down for about 10 minutes.

Sustainability

How strong is botulism? Microbiology suggests that the microorganism itself behaves differently, being in different states.

1. Spore form. In this case, clostridia are very resistant to various kinds of external changes. At a temperature of 6 ° C can live for about a month, when boiling at 100 ° C, they die only for an hour, at a temperature of 120 ° C - for half an hour. Spores are resistant to freezing, exposure to rays, drying. As for disinfecting solutions, a formalin solution (20%) can kill a bacterium in two days, ethyl alcohol - for two months, and a solution of hydrochloric acid (10%) - per hour.
2. The vegetative form. In this state, clostridia are very vulnerable. At a temperature of 80 ° C may die within an hour.
3. As for the toxin, it behaves the same way as the vegetative form. At 100 ° C for 10 minutes, the toxin can be neutralized. Stable in an acidic environment, but can be neutralized in alkaline. In the gastrointestinal tract, the toxin markedly decreases its activity. However, the exception is the type of botulism E, which, on the contrary, becomes more active in the human gastrointestinal tract 10,000 times.

Where maximally extends botulism? Microbiology, medicine say that most often patients are found in those countries where people are accustomed to eating meat or canned fish. Seasonality in this case does not matter. Also age, sex, color of a person are unimportant . Anyone can get infected.

Pathogenesis

Botulism is a severe food intoxication that can develop after consumption of food contaminated with clostridia or their toxins (the toxin is released when the microorganism enters the anaerobic environment and begins its active reproduction). The most important in the case of treating a disease such as botulism, is precisely the neurotoxin. It is important to say that it is he who is the strongest of all the existing biological poisons. According to scientists, it is 375 times more toxic and stronger than the poison of the rattlesnake. If you get the poison in its pure form, only 1 mg will contain up to 100 million lethal doses for a white laboratory mouse. As for the person, death can come after taking only 0.001 mg of neurotoxin.

About the neurotoxin

As already mentioned above, the bacteria clostridium botulinum secrete the strongest and most dangerous neurotoxin, which is a threat not only to health, but also to human life. It is also worth mentioning that this toxin is thermally stable. In the intestine gets in the form of prototoxin, into a dangerous microorganism is transformed after its treatment with enzymes of the small intestine. The effect of enzymes of digestion is stable. Distinctive feature: quickly absorbed into the blood, being already in the uppermost part of the gastrointestinal tract. With blood spreads through the body, getting into the neuromuscular synapses.

The stages of toxin action

Also it is necessary to tell that the toxin of botulism has three stages of action:

1. Reversible stage (if antitoxic serum is used). The neurotoxin binds to a specific receptor.
2. The transfer of toxin into the water part of the neuromuscular junction cell. Temperature is important for this stage. The very stage itself is difficult to reverse.
3. The lytic stage. In this case, the toxin blocks the conduction of a nerve toxin into the muscle. Here, the main symptoms of botulism develop.

Types of botulism

In medical practice, there are four main types of botulism:

1. Food, or classic. Infection occurs by consuming food that contains a toxin.
2. Ranewoy. This type of disease is associated with contamination of the human wound surface.
3. Botulism of newborns. It is a pathological infection of the intestines of a newborn baby with bacteria.
4. Uncertain classification. In this case, doctors can not say exactly what caused the infection with human botulism.

About infection

How does a person develop botulism? How does infection occur? First of all, it should be noted that it is impossible to become infected with a human clostridium. However, this microorganism enters the human body due to food contaminated with contaminated soil or feces. Further, for the occurrence of the disease itself, bacteria also need special conditions. So, if the food is going to be processed before the reception, the microorganism instantly turns into a spore form, which is very resistant to the high temperatures. After cooking, the spores begin to change into the vegetative state, when the clostridia secretes a deadly toxin. It is worth noting that the microorganism is afraid of open oxygen. Re-heating food is also not capable of killing a pathogenic bacterium (it needs a temperature of about 750 ° C to destroy it). Further, the infected food enters the human body, and the disease manifests itself quite quickly.

The incubation period

Botulinum toxin after exposure to the body begins to act immediately. This occurs in the first 8-22 hours after consuming contaminated food. However, the average time is 10-12 hours.

Clinical picture of the disease

What happens to the human body after infection with a given bacterium? So, at the very beginning, the symptomatology will be similar to gastroenteritis (an inflammatory process of the mucous membranes of the small intestine and stomach). The main symptoms that cause botulism are:

1. Abdominal pain, mainly in the navel. Pain will grow, spread.
2. The temperature most often does not increase.
3. The chair can be up to 20 times a day. Can be watery, plentiful, in the form of rice broth.
4. General weakness of the body.
5. Vomiting.

Vomiting and frequent stool can lead to general dehydration of the body. In this case, cramps may appear, there is an effect of wrinkles on the face, other skin integuments. Most often all symptoms disappear after a couple of days. A person thinks that he suffered a common intestinal flu. But it also happens that not everything is going so well and quickly. In some cases, a person may have stool and vomiting with blood impurities, and there may be very severe pain. All can end even fatal due to the appearance of necrosis of the intestine.

About outbreaks

Where is it more often possible to get infected with such a disease as botulism? The photos of the foci of infection are multiple, however, most often these are catering establishments, especially if a person consumes proteins of animal origin.

Prevention

What precautions can protect a person from infection with a given bacterium?

1. Can kill botulism by boiling. So, before eating any canned food, it is best to boil it for about 15 minutes. This will allow the toxin to break down. Also, you can not consume canned food, the lids of which are swollen.
2. The bacterium that causes botulism dies at low temperatures. If possible, meat and fish food products should be frozen before cooking. Store them also best at temperatures below + 10 ° C.
3. It is especially necessary to process mushrooms. Since it is on them that particles of clostridium infected soil can remain.
4. People who ate the same food as sick botulism, should be under the supervision of doctors. They also need to introduce amniototic antibotulinum serum and enterosorbents as a prophylaxis.

Forecast

What can end such a disease as botulism? Photos of former patients are different. It's like completely eliminated from the disease people, and the bodies of the dead. The last variant of the development of events is possible only if the patient does not provide timely appropriate assistance. Without treatment, botulism takes human life in 30-60% of cases.