Bohomolets Microbiology Lecture #21
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By Ms. Kostiuk from Microbiology department
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Bohomolets Microbiology Lecture #21
- 1. Agents of anaerobe infections Clostridia
- 3. Obligate anaerobes There are microorganisms that cannot multiply is any oxygen is present. Some members are actually killed by traces of oxygen because they cannot modify the toxic forms of oxygen produced in metabolism. Among the more important anaerobic pathogens are some species of Clostridium, Bacteroides
- 4. Enzyme content of bacteria with different requirement for oxygen Neither catalase nor superoxide dismutase Strict anaerobe Superoxide dismutase Aerotolerant Small amount of catalase and superoxide dismutase Microaerophile Catalase Superoxide dismutase Facultative anaerobe Catalase – H 2 O 2 H 2 O + O 2 Superoxide dismutase O 2 - +2H+ O 2 + H 2 O 2 H 2 O + O 2 Strict aerobe Enzyme content for O 2 detoxification Name
- 11. Cl.perfringens in the smear from wound exudate
- 12. Sporulation of Cl. perfringens
- 15. Lecithinase and hemolytic activities of Cl. perfringens Absence of lecithinase effect when antitoxin is used Hemolysis Lecithinase effect Absence of hemolysis when antitoxin is used
- 17. Gas gangrene therefore the gas forms in tissues due to fermentation of muscle carbohydrates, amino acids and glycogen.
- 18. Changes in the infected tissue The gas formed in the tissue can destroy muscle structure
- 19. Pathogenesis of gas gangrene Symptoms: pain, edema, and a bloody exudate in the lesion, fever, tachycardia, and blackened necrotic tissue filled with bubbles of gas.
- 28. Serotypes of Cl.botulinum and its connection with toxigenicity Bacterial chromosome - G Bacterial chromosome + F Temperate bacteriophage + E Temperate bacteriophage - D Temperate bacteriophage - С2 Temperate bacteriophage - С1 Bacterial chromosome + В Bacterial chromosome + А Location of tox-gen Human sensitivity Serotype
- 32. Guinea pig, effected by botulinum toxin
- 34. Cl.tetani morphology Spherical terminal spores
- 35. Cultural properties of Cl.tetani Swarming growth on the solid media
- 38. Clinical symptoms The first symptoms are clenching of the jaw, followed in succession by extreme arching of the back, flexion of the arms, and extension of the legs.
- 39. Death is most often due to paralysis of the respiratory muscles and respiratory collapse. The fatality rate ranging from 10% to 70%.
- 45. Action of B cytotoxin to colonic mucosa Yellow-white plaques formation on the colonic mucosa.
Editor's Notes
- Bacteria can be classified into some divisions based upon their requirments for gaseous oxygen or air, which contain 20% oxygen.
- Why are some anaerobes killed in the presence of O 2 , but others can tolerate in even though they cannot use it? Oxygen can be converted into a number of forms that are highly toxic. Some of these toxic forms, such as hydrogen peroxide (H 2 O 2 ), are formed by metabolic processes involving O 2 . Other toxic compounds, such as superoxide O 2 -), are produced as a chemical reaction on light. Cells that are not killed in the presence of oxygen contain enzymes that can convert these toxic compounds to nontoxic forms.
- Therefore clostridia are anaerobes, they need special condition of growing in host orgamism (without oxygen) and this feature influence to pathogenesis – as usual, bacterium must infect wound
- Spores are not sensitive to Gram-staining and are shown as uncolored space in the vegetative cell or separately situated uncolored oval cells.
- Theta toxin
- The enzymatic activity of toxin can be demonstrated by growing the organism on a media containing egg yolk. It hydrolyses lecithin in the egg yolk and changes its color.
- Almost every sample of soil and dusty surface has spores of the gas gangrene bacillus. However, only rarely does contamination of a wound result in gas gangrene. The low oxygen condition results from the presence of aerobic bacteria that deplete oxygen. Such condition stimulate spore germination, rapid vegetative growth in the dead tissue, and release of exotoxins.
- Surgical removal of infected tissue is of primary importance. If treatment is not indicated early, the disease if invariably fatal.
- Diagnosis depends mostly on patient’s symptoms
- Diplopia – double vision Dyphagia – cannot swallow
- Cl.Botulinum species has 8 distinctly different types (A, B, C1, C2, D, E, F, G), which vary in distribution among animals, regions of the world, and the type of exotoxin. Human disease is usually associated with types A, B, E, and F, and animal disease with types A, B, C, D, E. In C, D, F strains, toxin production results from lysogenic conversion
- The toxin is moderately inactivated by boiling contaminated food for 15 minutes. The antitoxin only neutralizes toxin circulating in the blood stream, and the nerves already affected by it recover slowly, requiring weeks or months.
- The most available method is identification of toxin in patient’s blood and food.
- Tetanus is a neuromuscular disease whose alternate name, lockjaw, refers to an early effect of the disease on the jaw muscle.
- Cl.tetani shows 2 striking features. The first feature is the spherical endospore that forms at the end of the bacillus, in contrast to the oval endospore that develops near the center the center of the rods in other pathogenic species of Cl.
- The second feature is its swarming growth that spreads to cover the entire surface of solid media.
- Laboratory diagnosis has limited value. The main position – clinical symptoms of tetanus is so striking and high specific than do not require laboratory conformation. Isolation of Cl.tetani from wounds does not prove that a person has tetanus. Conversely, failure to find the organism in a patient’s wound cultures does not eliminate the possibility of tetanus. False negative results occur in up to 2 thirds of patients. The reasons for these observations are that tetanus exdopsores may contaminate sounds that are not sufficiently anaerobic to allow germination and toxin production, or the person may simply be immune to the toxin by prior vaccination.
- Paralysis develops since lower extremities and tail to upper part of body. In human - on the contrary, tetanus develop since back of the head and go down to extremities.
- Tetanus has a high mortality but is easily prevented by immunization.
- Cl.defficile is part of the flora of the gastrointestinal tract approximately 3% of the general population.