Clostridium botulinum

Clostridium botulinum

Clostridium botulinum is a gram-positive, rod-shaped bacterium from the family of endosporenbildenden Clostridiaceae. The diameter is 0.5-1.0 microns and a length of 2-10 microns. The spores are oval, subterminal usually arranged, and often wider than the mother cell. Although it is an anaerobic bacterium, it is relatively insensitive to atmospheric oxygen. For the first time isolated the Belgian microbiologist Emile van Ermengem 1897, which initially proposed the name Bacillus botulinum. Isolation from sausage ( from Lat botulus ) and the first time observed relationship with the already known disease botulism was eponymous.

C. botulinum consists of several biochemically different groups whose only common feature is the formation of botulinum toxin. Eight different toxins ( A, B, C1, C2, D, E, F and G) are formed, only the types A, B, E and F are pathogenic to humans. Types C and D are pathogenic to animals. In the rare toxin type G, there are few case reports in humans. However, some strains of Clostridium butyricum and Clostridium botulinum toxins baratii also form. Closely related clostridia, but not produce botulinum toxin, were taxonomically classified under the name of Clostridium sporogenes.

Groups

Since the taxonomy is exclusively based on the production of toxins belong to the species from diverse organisms metabolism, which are divided into four phenotypic groups. Sequencing of the 16S rRNA and nucleic acid hybridization reactions have confirmed the four lineages.

Toxin

The seven toxin types (A to G) can be serologically distinguished by neutralization with an anti- toxin. Some strains are able to form two neurotoxins.

If Clostridium botulinum toxins absorbed from the intestine into the blood, so they reach the peripheral neuromuscular synapses. Here BTX is taken endoneural and blocks the release of the neurotransmitter acetylcholine. The death rate is highest for type A, followed by type E and then type B, which may be explained by the binding affinity to the nervous tissue. Toxin type A is used therapeutically to treat involuntary muscle spasms and some focal dystonias.

Pathogenesis

The best known form is the food poisoning by botulinum toxin. The wound botulism, in which the pathogen grows in dead tissue, however, is rather rare. In infant botulism, the spores are picked up and germinate in the intestinal tract, where it comes to toxin production. First, the cranial nerves are affected, thus seeing, hearing and speaking impaired. Typical is double and blurred vision, dilated pupils and slurred speech. A reduced saliva production ensures a dry mouth and makes swallowing painful. Later, the motor nerves are paralyzed, which is expressed in a general feeling of weakness. Death results from paralysis of the respiratory muscles or cardiac arrest.

Epidemiology

The spores are found worldwide in water and sediments in small quantities in the gastrointestinal tract of birds, fish and mammals. In the USA toxin type A is widely used in Europe Type B.

Food hygiene

In hermetically sealed canned meat, especially sausages, fish, vegetables, fruits and spices, the spores can germinate and produce toxin. In particular, inadequate heated home-canned preserves are affected. Children under 1 year old should consume no honey, as spores may be present that can cause infant botulism. Other input sources are dust and earth.

Are contradictory studies regarding the contamination of corn ( starch ) syrup with Clostridium botulinum spores. In a study from 1982, a contamination level was 1.3% of the tested corn starch syrups of 50 spores per gram found in a later study (1988 ) is no spores found in 43 samples of syrups of different origins, 1991 no spores at 738 samples of corn syrup or products containing these.

Maple syrup may contain, due to the dust in the extraction and in the course of processing further increased microorganisms, including Clostridium botulinum.

Diagnostics

To distinguish whether a proteolytic or non- proteolytic strain is present, a cultured on calf liver egg yolk agar or anaerobic egg yolk agar ( AEY ) can take place. The colonies irisieren at oblique incidence, however, are indistinguishable from non-toxic clostridia. Enrichment can in tryptone - peptone -glucose -yeast extract medium ( TPGY ) or cooked meat medium ( CMM) take place. Subsequently, the toxin can be detected by mouse bioassay, wherein the test animals, a dilution series is injected into the diaphragm, and the typical symptoms of botulism ( respiratory paralysis, wasp waist ) can be observed. To determine the toxin type some animals the respective antitoxins are administered beforehand. Furthermore, an Amplified and a DIG- ELISA is possible. Since the sequences of the toxins are known, a nucleic acid detection by PCR, is also available. The Mausbiosassay is in Germany for the official control of foodstuffs the reference method in accordance with § 64 LFGB dar.