Pathogenesis

Question 1

parasite

Answer 1

consumes host resources at expense of host

Question 2

pathogenesis

Answer 2

disease

Question 3

pathogenicity

Answer 3

microbes ability to cause disease

Question 4

virulence

Answer 4

quantitative measure of pathogenicity (degree and efficiency)

Question 5

primary pathogen

Answer 5

causes disease in healthy individual

Question 6

opportunistic pathogen

Answer 6

doesn’t harm healthy individual, but when host environment changes (like becomes immunocompromised), disease occurs
e.g. toxoplasma

Question 7

human exposed surfaces

Answer 7

• GI tract, mouth, respiratory tract, urogenital tract
• sterile environments: blood and organs

Question 8

how does the skin defend against pathogens

Answer 8

• secrete lipids to prevent drying
• lactic acid and lysozyme
• e.g. propionibacterium acnes causes acne

Question 9

how does mucous membranes protect against pathogens

Answer 9

• physical barrier: tightly lined epithelial cells
• chemical barrier: mucus secretes solubles with antimicrobial activities

Question 10

what is plaque and what bacteria cause it to form

Answer 10

• large biofilm
  1. streptococcus colonizes which causes plaque
  2. filamentous fusobacterium thicken plaque
  3. anaerobic actinomyces grow in thick plaque

Question 11

how does tooth decay occur

Answer 11

• pathogenesis is a shift to bad bacteria
• streptococcus mutans is bad bacteria which begins to colonize

Question 12

bacteria associated with ulcers

Answer 12

• h.pylori
• lophotrichous and uses flagella to invade mucus
• secrete urease to alter local pH
• cleared with antibiotic treatment

Question 13

5 things that make a successful pathogen

Answer 13

1. access to host and appropriate tissue
2. evade host defenses
3. establish a niche
4. replicates through host nutriet acquisition
5. damage to host

Question 14

7 common features of infection

Answer 14

1. exposure
2. adherence (using pili or glycocalyx)
3. invasion
4. growth and dissemination
5. virulence factors (measured by LD50 and attenuation is when virulence is reduce - problems with any of the other steps or loss of virulence factor)
6. evade host damages
7. host cell damage

Question 15

how can we find virulence gene

Answer 15

• virulence assay (mutant transponson assay)
• genome comparison between similar pathogenic and non-pathogenic species

Question 16

4 type of toxins

Answer 16

1. endotoxin (LPS) cell associated with gram (-) and cause systemic fever and inflammation
2. exotoxins secreted into environment:
3. cytotolytic toxins (pore formers or phospholipases): cause cell lysis
4. AB toxins: two subunits - B binds to host receptors and A enters cytoplasm
5. Superantigen toxins: simulate significant immune response

Question 17

AB toxin in cholera

Answer 17

• B binds to host receptor GM1
• A delivered to cytoplasm and interferes with cAMP pathway
• ion movement is disrupted and move to lumen rather than blood
• water follows ions into lumen and out of the body causing diahrea
• cholera that are pathogenic have a toxin co-regulated pili that were orginally to recieve bacteriophage

Question 18

trypanosome life cycle

Answer 18

• in the gut of tsetse fly
• transferred to bloodstream and CNS of human host
• vector borne parasite

Question 19

how to trypanosome fight against adaptive immunity?

Answer 19

• adaptive immune system makes antibodies
• typanosome goes through antigenetic variation after each cycle, expressed antigens change
• this gives waves of fever and parasite count
• they create this variation by switching what telomere expression sites are on or by recombination

Question 20

immunofluorescence assay

Answer 20

• similar to FISH
• attaches fluorescence onto antibody and when antibody binds to antigen, a signal is produced

Question 21

how to trypanosome fight against innate immunity?

Answer 21

• innate immune system: lytic factor in our serum
• certain trypanosomes show resistance to this serum