Biomed Module 6 obj. 8-9
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What is a pathogen?
An organism that leads to infection or disease in the host.
__________ often results in disease in the host.
___________ depends on the organism's ability to invade the host, multiply, and avoid ________ from the hosts ________.
Pathogenicity, damage, defenses
- a term used to describe the intensity of bacterial and other microbial infections.
- Varies greatly among different organisms, but is always a factor in infection.
- Specific pathogenic mechanisms are contributors to virulence
What are the specific pathogenic mechanisms of bacteria?
- 1. Adherence
- 2. Colonization
- 3. Formation of a capsule
- Bacteria use their pulu to cling to the surface of the host cells
- multiply and form colonies.
- Once in place within the jhost tissue, bacteria replication forms colonies and may overcome the hosts defenses.
- Colonization by small numbers of non-invasive organisms is normal in all animals including humans.
Formation f a capsule
In certian pathogens the capul contributes to the organisms virulence because this thick, polysaccharide structure helps organisms resist host defense processes.
_________is the abiltiy of organisms to penetrate host tissue , usually via special ________.
What are the enzymes tht contribute to invasiveness ?
- Steptokinase and staphylokinase
- Known as the spreading factor
- produceced by streptococci, staphylococci, and some other pathogens
- Attacks hyaluronic acid, the ground substance or connective tissue.
- An enzyme produced by some bacteria that accelerates the clotting of blood
- Breaks down collagen, the framework of muscles
Streptokinase and staphylokinase
- Kinase enxymes digest fibrin and prevent the clotting of blood
- this results in reduciton of fibrin allowing more rapid difusion of the infectious bacteria in the host tissue
- exampel : streptococus stain of "flesh eating bacteria"
What are the types of toxins produces by bacteria?
- Very powerfl toxins secreted by the living bacterial cell
- Mostly from gram positive organisms
- Gram positive examples: botulism, gas gangrene, tetanus, staphylococcal food poisoning
- Gram negative exotixin: E. coli
- Found primarily in gram negativ bacteria
- Are releases only when the oragnism (bacteria) dies.
- Cause non-specific gastrointestinal symptoms such as diarrhea, cramping, and generalized malaise
- Examples: cholera, salmonella
True or False: Endotoxins may cause the death of many organisms, leading to anaphylactic shock syndrome, when given doses of antibiotics.
When conditions become unfavorable, bacteria form _________ which is a ______ form.
Endospores have __________ cell walls to withstand ______________ _______ such as drying and lack f nutritional sources.
thickened, environmental extremes
True or False: Once conditions become favorable endospores revert to vegetative (active) cells and regrowth processes can begin
- Dormant stage of some bacteria
- Form when nutritional and enviornmental conditions are unfavorable for growth.
- Survival under harsh conditions- excessive cold, heat, or dryness
- Revert to acive cells under favorable conditions
- Important bacteria that form endospoeres include the clostridiums that cause disease when endospores germinate in the human host.
- Clostridia species that cause tetanus, botulism, and gas gangrene form endospores.
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