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Microbiology > Lecture 20: Pathogenesis > Flashcards

Lecture 20: Pathogenesis Flashcards

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Biology 101 flashcards
1
Q

Pathogenesis

A

The steps that are involved in the origin and development of a disease

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2
Q

Pathogenicity

A

The ability of an organism to cause disease or induce damage to the host

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3
Q

Virulence

A

The degree of pathogenicity

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4
Q

Steps of bacterial pathogenesis

A
  1. Source or Reservoirs
  2. Entry into the host
  3. Attachment & colonization
  4. Invasion of Host Tissues/ Evading Host defenses
  5. Growth and multiplication
  6. Leaving the host
  7. Enter into new host
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5
Q

Modes of microbial transmission

A
  1. Inhalation/ Repiratory
    -Cold and Flu
  2. Ingestion of contaminated food/water
    -Rotaviruses
  3. Blood or bodily fluids
    -HIV and Hepatitis
  4. Through insect bite-arbovirus
    -West Nile, Lyme, EEE
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6
Q

Zoonosis or zoonose

A

Any infectious disease that can be transmitted from non-human animals, both wild and domestic, to a human

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7
Q

How do pathogens cause disease?

A
  1. Cell lysis
  2. Cell dysfunction
  3. Immune responses-Inflammation
  4. Immunodeficiency
  5. Cancer
  6. Produce toxins (Bacteria)
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8
Q

Cell lysis example

A

Poliovirus

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9
Q

Poliovirus

A

-Tropism for motor neurons in spinal cord -Enteric virus in the Picornaviridae family
-Soon to be eradicated

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10
Q

Poliovirus outcomes

A
  1. Asymptomatic—90-95%
  2. Minor illness—4-8%
  3. Non-paralytic aseptic meningitis—1-2%
  4. Paralytic poliomyelitis—0.1-0.5%
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11
Q

Polio transmission

A

Fecal-oral
GI track—>Lymphatics—>Blood (viremia)—>CNS

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12
Q

Ebola virus

A

•Filoviridae family
•1976 outbreak
•Spread by body fluids
•Fruit bat—>great apes—>human

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13
Q

Ebola virus disease

A

•Dysfunction and inflammation work together
•Cytokine production and virus attachment to blood vessels lead to a loss in vascular integrity
•No coagulation (damage to liver)
•Hypovolemic shock

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14
Q

Inflammation

A

•Immune system can cause damage when trying to control infection
•Immune response causes disease
-Influenza and COVID
-Cytokine storm

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15
Q

Inflammation& the brain: meningitis

A

•The swelling and irritation (inflammation) of the membranes covering the brain and spinal cord
•can be bacterial, fungal, or viral

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16
Q

Pelvic inflammatory disease

A

•Usually due to chronic infection of:
-Chlamydia trachomatis
-Neisseria gonorrhoeae

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17
Q

Immunodeficiency ex. HIV

A

•Human Immunodeficiency Virus (Lentivirus family)
•HIV infects helper T cells, dendritic cells , and macrophages
-Kills helper T cells and causes them to undergo apoptosis

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18
Q

•Immunodeficiency ex.
Measles

A

-5-6th leading cause of death in children
-“Immune Amnesia” lasts for 2 years or more
—Increase in secondary infections
—Diminishes prior immunity to past infections

19
Q

How do some microbes cause cancer

A

Uncontrolled growth of abnormal cells in the body due to increased cell proliferation, decreased apoptosis, and metastasis

20
Q

Mechanism of oncogenecity

A

Direct—Introduction of new “Transforming gene” into the cell
Indirect—Alteration of expression of pre-existing cellular gene
Leadings to:
-Loss of normal growth regulation processes
-Affection of DNA repair mechanisms
-Genetic instability
—Mutagenic phenotype

21
Q

Oncogenic bacteria

A

•Heliobacter pylori—Stomach cancer
•Salmonella typhi—gall-bladder cancer
•Streptococcus bovus—Colon cancer
•Chlamydia pneumonias—lung cancer
•Bartonella—vascular tumors
—15% of cancer cases were attributed to a carcinogenic infection

22
Q

Dr. Peyton Rous

A

• Won Nobel prize for showing that viruses can cause cancer
-Chickens grow a tumor called fibrosarcoma
-Rous ground up these sarcomas, centrifuged them to remove the solid material, and injected the remaining liquid into chicks
-The chicks developed sarcomas
-The purified oncogenic virus called Rous sarcoma virus (RSV)

23
Q

Oncogene

A

Some pathogens have oncogenes
•A mutated gene that promotes cell proliferation and blocks apoptosis
—Proto-oncogenes are healthy genes that enhance cell growth, division, and survivability
•Ex: v-Sec in Rous Sarcoma Virus (RSV)

24
Q

Tumor suppressor genes

A

Some pathogens have a protein that blocks a Tumor suppressor gene
•Tumor suppressors are genes that block cancer progression
—found in host cells
—Surveillance
—p53 is an example

25
Q

How can Bacterial or viral genes alter host cell behavior

A

•Host cell cell cycle—proliferation
•Cause or block apoptosis
•Cell adhesion/attachment
•Activate cell signaling pathways for migration
•Increasing cell turnover—> more spontaneous mutations
•Chronic inflammation —> DNA damage due to ROS

26
Q

HPV

A

•A few types of HPVs are associated with 82% of the cervical cancers
•Cervical cancer: 2nd largest cause of female cancer mortality worldwide
•Major cause of throat and esophageal cancer

27
Q

Heliobacter pylori

A

•H. Pylori in 1/3 of all adults in the US, causes inflammation of the mucous membrane of the stomach
-In 20% of infected persons, H. pylori induces gastric ulcers
-60-90% gastric cancers caused by H. pylori
-Increases risk of developing gastric cancer by 6x
-CagA in some strains of H. pylori

28
Q

Hepatitis C virus

A

•Cells stop regenerating
-Cirrhosis
•Increase chance of mutation
-Cancer

29
Q

How do chronic infections cause cancer (Hep C/H. pylori)

A

Chronic lytic infections increase cell death and cell turnover. Greater cell division to compensate for cell loss can lead to more DNA mutations

30
Q

Chronic infections lead to …

A

Chronic inflammation

31
Q

Chronic inflammation causes..

A

•Reactive oxygen species (ROS)
-Cell proliferation
-Apoptosis
-Signal transduction
-DNA damage
•Reactive nitrogen species
•Inflammatory cytokines cause cell proliferation

32
Q

Burkitt’s Lymphoma

A

•Genomic instability
•Epstein Barr virus (Herpesvirus) infects B cells
•Integrates genome which make double-stranded breaks in DNA
•Chromosome translocation occurs:
-Now human Myc gene (oncogene) is controlled by an active promoter that controls antibody production

33
Q

Bacterial toxins

A

•Endotoxin
•Exotoxin

34
Q

Endotoxin

A

Structural components of gram- cell walls
•Lipopolysaccharide
-Released when bacteria break down or divide
-Endotoxins do not cause cell damage on their own, but stimulate immune system
—shock-like symptoms…chills, fever, weakness, fatigue, small blot clots

35
Q

Exotoxins

A

Secreted toxins

36
Q

Exotoxins ex. Staphylococcus toxins

A

Leucocidin-Leukocyte lysis
Hemolysis-Red blood cell lysis
Coagulate-Fibrin clotting

37
Q

Streptokinase exotoxins

A

Streptococci (Gram positive) produces streptokinase-the clot buster enzyme

38
Q

Type of exotoxin

A

AB toxins (active/binding)
•Cholera toxin
•Anthrax toxin
•Tetanus toxin

39
Q

Botox (Botulinum toxin)

A

Botox injection inhibits release of acetylcholine (ACh)
-Muscles are in relaxed state and cannot contract

40
Q

Tetanus toxin

A

-Clostridium tetani

Toxin prevents release of inhibitory neurotransmitter: GABA and glycine=Muscle spasm

41
Q

Different toxins-Same environment-different outcomes example

A

Small intestine
-Shiga toxin (E. Coli): Epithelial and endothelial cell lysis-bloody diarrhea
-Cholera toxin:
Water release into gut-Rice-water stool

42
Q

Cholera toxin

A

Cholera toxin influences chloride channels in the cells that line the gut causing these cells to release water into the small intestines

43
Q

How does E. coli deliver toxin

A

E. Coli can attach and deliver toxins
-Shiga toxin can block protein synthesis which leads to immediate death of cells and breakdown of the IT barrier

Microbiology (13 decks)

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