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Laboratory Diagnostics of the Anaerobic Infections

What is the morphology of anaerobic infection causative agents? They are large gram-positive spore-forming mobile rods (Clostridium), gram-positive bacilli (Actinomyces, Lactobacillus, Propionobacterium, Eubacterium, bifidobacterium), gram-positive cocci (Peptostreptococcus), gram-negative bacilli (Bacteroides, Prevotella, Porphyromonas, fusobacteria),gram-negative cocci( Veilonella).
What diseases are caused by Clostridium? C. tetani causes tetanus, C. botulinum causes botulism, C. perfringens, C. septicum, C. histoliticum, C. novii cause the gas gangrene, C. difficile causes pseudomembranous colitis.
What is the natural habitat of the Clostridium? It is the soil.
What is the condition of the Clostridium cultivation? Clostridia grow only in anaerobic conditions, on the special media.
What is the pathogenesis of botulism? During the growth C. botulinum toxin is liberated into the environment. The toxins are neurotoxic proteins of similar structure and action. They are made up of heavy and light chain linked by disulfide bond. The light chain blocks the calcium mediated release of acetylcholine resulting in Flaccid paralysis.
What are the typical clinical manifestations of botulism? Symptoms develop in 18-24 hours after ingestion of the toxic food, with visual disturbances (incoordination of eye muscles, double vision), inability to swallow, and speech difficulty, signs of bulbar paralysis are progressive, and death occurs from respiratory paralysis or cardiac arrest. Gastrointestinal symptoms are not regularly prominent. There is no fever.
What is the pathogenesis of the tetanus? Vegetative cells of the C. tetani produce tetanospasmin and release it mainly when they lyses. Tetanospasmin acts in several ways upon the central nervous system. It inhibits the release of acetylholine, thus interfering the with neuromuscular transmission. The most important action is the inhibition of postsynaptic spinal neurons by blocking the release of an inhibitory mediator resulting in hyperreflexia and muscle spasms that may be generalized.
What are the typical clinical manifestations of the tetanus? The incubation period may range from 4-5 days to as many weeks. The disease is characterized by tonic contraction of voluntary muscles. Muscular spasms often involve first the area of injury and infection and then the muscles of the jaw, which contract so that the mouth cannot be opened. Any external stimulus may precipitate a titanic generalized muscle spasm. Death usually results from interference with the mechanics of respiration.
What is the pathogenesis of the gas gangrene? The clostridia produce a large variety of toxins and enzymes that results in spreading infection. These toxins have lethal, necrotizing, and hemolytic properties. When the spores contaminate the tissue they transform in the vegetative cells. These cells produce the ferment carbohydrates and gas. The distention of tissue and interference with blood supply, together with the secretion the necrotizing toxin and hyaluronidase, favor the spread of infection. Tissue necrosis extends, providing an opportunity for increased bacterial growth, hemolytic anemia, and severe toxemia and death.
What is the active specific prevention of the Clostridia anaerobic infection? It is using the toxoid.
What is the passive prevention? It is using specific antitoxic serum.

Addition 2.



Microbiological research of the material in the tetanus

Pieces of tissue, pus swab, discharge from uterine, catgut, towels.

 

Microbiological research of the material in the gas gangrene

 


Date: 2016-01-14; view: 519


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