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Pathophysiology 212 > Mechanisms of infectious diseases > Flashcards

Mechanisms of infectious diseases Flashcards

1
Q

Commensal Flora

A
  • Over 300 different species of bacteria live in the large intestine
  • Bacteria and fungi live on our skin
  • Mouth and pharynx contain many bacteria
  • Vagina contains acid-producing bacteria
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2
Q

Compare and Contrast Mutualism and Parasitic

A

Mutualism:
Both the host and microorganism benefit

Parasitic:

  • Only infecting organism benefits
  • Typically host doesn’t die
  • Infectious means host sustains injury
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3
Q

Terminology

A 
1. Virulence
Disease producing potential
2. Pathogen
Very virulent microorganisms
3. Saprophyte
Environmental organisms that feed off dead/decaying organic material
Usually fungi
Harmless to humans, but can be opportunisitic organisms if host immune system is compromised
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4
Q

Agent of Infection: Prions

A
  • Abnormally shaped proteins that cause normal proteins to change their shape and thus become new prions
  • Propagation is unclear so difficutly to treat
  • Doesn’t reproduce, but uses existing protein
  • Cause neurodegenerative diseases of CNS
    e. g. Creutzfeldt jakob disease
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5
Q

Viruses

A
  • Small, no organized cellular structure
  • Incapable of replicating outside a living cell
  • Protein coat surrounded by a nucleic acid core
  • Some have lipoprotein envelope
  • Inserts genome into host cells DNA, then uses cells energy
  • Grouped by size, composition, how it replicates/transmits, resulting disease, etc.
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6
Q

Compare latent and oncogenic viruses

A
  1. Latent viruses
    Enter cell insert genome, remain dormant until stimulated
    - Varicella zoster, Epstein-Barr virus, herpes
  2. Oncogenic viruses
    - Can transform host cells to malignant cells during replication
    Human papillomavirus (HPV)
    Epstein-Barr, Hep B
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7
Q

Compare influenza, retrovirus, and enterovirus

A
  1. Influenza viruses
    - H1N1, H3N2
  2. Retrovirus group
    - Unique replication
    - HIV/AIDS (unique replication)
  3. Enterovirus
    - Single stranded RNA virus
    - Found in mucous, saliva, stool of infected person
    - Poliomyelitis
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8
Q

Bacteria and it’s characteristics

A
  • Small, simple structure
  • Cytoplasm covered by rigid cell wall that is susceptible to anti-bacterials
  • Can live independently, but uses organism’s nutrients
  • Contains both RNA & DNA
  • Flagella: propel bacteria
  • Pili: filaments that help adherence
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9
Q

Bacteria shapes/types and definitions

A
  • Streptococci: divide into chains
  • Diplococci: divide into pairs
  • Staphylococci: divide into clusters
  • Biofilm = structured community of bacteria
  • Spores = group waiting for favorable conditions to replicate
  • Aerobic = requires oxygen
  • Anaerobic = hates too much oxygen
  • Facultatively anaerobic = can adapt to oxygen rich or poor environment
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10
Q

Types of bacteria con’t

A

Gram positive/Gram negative
- Stain red/blue
Acid-fast bacilli = don’t stain

Spirochets: helical, long bacteria

Mycoplasms
Smaller than normal bacteria
Resistant to some antibiotics

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11
Q

Organisms having both viral and bacterial characteristics

A
  1. Rickettsiaceae
    - Carried by fleas, ticks, lice
    - Need host nutrients & cell ATP byproducts
    eg: rocky mountain spotted fever, typhoid fever
  2. Chlamydiaceae
    - STI
    - Ocular infection in newborn
    - Respiratory infections
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12
Q

Fungi

A

-Only a few cause serious disease
-Require temperature < body so usually on surface
-Often self-limiting
-Not susceptible to penicillin-like antibiotics
Yeasts: waxy/creamy texture
Molds: cottony/powdery colonies

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13
Q

Parasites & Transmission

A 
Protozoa (unicellular animals)
Transmission
Host to host (sexual contact)
Arthropod vector
Contaminated food/water

Malaria, dysentery (both parasites)

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14
Q

Helminths (wormlike) parasite

A

-Roundworms, tapeworms, flukes
-Any body organ (or numerous)
e.g. intestinal parasites
Transmission:
-Ingestion of fertilized ova
-Penetration thru skin (arthropod vector)

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15
Q

Arthropod parasite

A 
Ticks, mosquitoes, flies, mites, scabies, lice, fleas
Transmission
- clothing/bedding/combs/brushes
Bubonic plague (fleas)
Epidemic typhus (lice)
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16
Q

Portal of Entry

A 
1. Penetration
Primary, accidental, medical
2. Direct Contact
3. Tissue/secretions, congenital
4. Ingestion
Must survive pH, enzymes, peristalsis, normal flora
Inhalation
- Must survive mucus, cilia, coughing, antibodies, phagocytes
17
Q

Sources of infection

A

Endogenous
- Opportunistic normal flora

Exogenous
- Human, fomite, animal, arthropod, inhalation

Nosocomial – hospital aquired

Community Acquired

18
Q

what makes an infection more likely to result in a disease? Virulence factors

A

Toxins = substances that alter or destroy normal cells

Exotoxins are proteins released from bacteria during growth
- Inhibit cellular synthesis

Endotoxins are lipopolysaccharides from cell wall of G-bacteria when gram-negative bacteria destructs:

  • Induce cytokines, leukocytes, T-lymphocytes
  • Results in increased capillary permeability
  • Less potent than exotoxins
19
Q

Virulence Factors (cont)

A
  1. Adhesion factors
    - Help infective organisms stick to the body
  2. Evasive factors
    Able to evade host immune system
    E.g. H. pylori
  3. Invasive factors
    Products produced by infectious agent to help it move across barriers (e.g. cell walls).
20
Q

Disease Course/Stages

A 
1. Incubation
Influenced by? Portal of entry, dose, health of the individual
2. Prodromal: initial symptoms
3. Acute: maximum impact
4. Convalescent: getting better

Chronic infections can have a
different course!

21
Q

Diagnosis

A
  1. Culture = propagation of microorganisms outside body with artificial growth media
  2. Serology = study of serum
    - Measure antibody response to infectious agent: antibody titer
    - Not as accurate as a culture
  3. DNA/RNA Sequencing
22
Q

Type of Antibiotics

A

Bactericidal:
- lethal to bacteria

Bacteriostatic:
prevents bacteria from replicating
Relies on host’s immune system to kill bacteria

Broad spectrum:
- G & G bacilli

23
Q

How do antibiotics kill bacteria?

A

Antibiotics kill bacterial by affecting:

  • Cell wall synthesis
  • Protein synthesis
  • Nuclei acid synthesis
  • Bacterial metabolism

Bacteria fight back by:

  • Inactivating antibiotics by creating enzymes
  • Changing antibiotic binding site
  • Using different metabolic pathways
  • Changing their walls to keep antibiotics out
24
Q

Antiviral agents

A

Antiviral Agents block:

  • Virus’s RNA/DNA synthesis (replication)
  • Binding to cell
  • Production of protein coat
25
Q

Anti-fungal agents

A

Target cell wall as substances are different than normal body cell wall

26
Q

Surgical Options

A
  1. Drain
  2. Debridement (take away dead cells from wound)
  3. Removal
    -Appendectomy
    amputation
  4. Replacement
    Heart valve

Pathophysiology 212 (18 decks)

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