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24 Cards in this Set
- Front
- Back
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What are two important microbial concepts of disease?
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Shear numbers
Presence of virulent organism |
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What are three host factors that affect disease?
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1. Non-specific resistance (physical barriers, PMNs, acidity, clearing mechanisms)
2. Immunity from prior exposure (humoral and cell-mediated) 3. Genetic composition |
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What are the most successful parasite?
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Normal flora
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________ is the ability of a GROUP of organisms to produce disease.
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Pathogenicity
*Group of organisms from a species or genus |
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________ is the capacity for a given STRAIN to produce illness.
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Virulence
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Explain the difference between pathogenicity and virulence.
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Example:
Shigella species are more pathogenic than Escherichia species. But a specific strain of E. coli is more VIRULENT than Shigella. |
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Why is adherence an important virulence characteristic?
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Allows attachment to the host that results in overgrowth of commensals and localized damage to permit colonization and infection.
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____ attach to host receptors to allow adherence.
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Fimrbiae and pili
*Present in ETEC and N. gonorrhoeae |
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Name some ways bacteria resist phagocytosis.
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Encapsulated organisms
Deficiency of opsonic activity (due to splenectomy) Surface factors |
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Give some examples of bacteria whose surface factors allow them to resist phagocytosis.
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K1 Antigen in E. coli
M Protein in S.pyogenes Capsule in S. pneumoniae |
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What virulence characteristic of S. aureus explains formation of boils?
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S. aureus is coagulase positive.
This allows clotting of vessels that leads to localized abscess formation. |
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How does S. pyogenes infection result in lymphangitis?
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S. pyogenes has spreading factors such as hyaluronidase, collagenase, and hemolysins that allow it to spread throughout tissue and along lymph vessels.
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Give some examples of diseases caused by exotoxins.
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Botulism
Tetanus Traveler's diarrhea Hemorrhagic colitis Antibiotic-associated colitis Gas gangrene |
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Which type of bacteria group all contain endotoxin?
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Gram negative because of the presence of LPS on their cell wall.
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________ is the mediator of septic shock and also is the #1 cause of death in the ICU.
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Endotoxin
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Endotoxin and Sepsis Syndrome:
Endotoxin release leads to ?? |
Cytokine release
Complement activation Platelet activating factor Nitrous oxide |
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The downsteam events that then occur in sepsis are ??
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Arachidonic acid metabolites
Damaged vascular endothelium Increased blood coagulability Myocardial depression |
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The resultant conditions that can arise are ??
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1. SIRS = systemic inflammatory response syndrome (tachypnea,-cardia, decreased bp and fever)
2. ARDS = acute respiratory distress syndrome 3. DIC = disseminated intravascular coagulation (bruises over entire body) 4. Shock 5. Renal Failure 6. Death |
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Name some microbes that must invade tissue to become virulent.
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Viruses
Rickettsia and Chlamydia Systemic fungi |
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What are some genetic factors that increase host susceptibility to certain infectious diseases?
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Receptors for microbial attachment
Blood group antigens : Type O are more susceptible to cholera an shigella infections HLA-B27 = enteric infection and reactive arthritis association Markers of inflammation can increase susceptibility |
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Name some microbes that can persist or remain latent in their host.
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M. TB
DNA (herpes) viruses Retroviruses |
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____ ___ describes the preference of certain microbes for specifice locations in the body.
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Tissue Tropism
Ex. hepatitis virus --> Liver Shigella --> gut |
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Name some factors that alter the balance between humans and microbes that are important for emerging infectious diseases.
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host
microbe general environment ecology political social economic factors |
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___________ in more than 300 million children predisposes them to infection and a protracted clinical course where tissue repair & function is retarded in intestine, heart and soft tissues.
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Malnutrition
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