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MIMM 211 > Bacteriel pathogenisis > Flashcards

Bacteriel pathogenisis Flashcards

1
Q

Relevance of bacterial pathogenesis

A

-historically high disease burden
-plague is still around
-new threats (new virulence factor combos and evolving bacteria
-climate change is altering range of vector
-antimicrobial resistance (no longer affected by antibiotics)

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2
Q

Modern big bacteria killers (2)

A

Tuberculosis and pneumonia

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3
Q

Story of bacterial ulcers?

A

-thought that there was no bacterial cause to ulcers
-Marshall ate food left out for days
-puked a lot, endoscoped stomach, found H. pylori
-won a nobel prize

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4
Q

H. pylori and ulcers
gram type, affected population, symptoms

A

-gram (-)
-infects 30-50% of population
-neutralizes stomach acid (production of urease
-inflammation + disrupted stomach mucosa = ulcers
-ulcers are linked to gastric cancer

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5
Q

Whats a pathogen

A

disease producer

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6
Q

Defining a pathogen?

A

Kochs postulates

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7
Q

Koch’s postulates + issues

A

-if present, causes disease (pathogens can be isolated from healthy individuals)
-isolate from diseased individual and cultured (some organisms are hard/impossible to culture)
-should cause disease when reintroduced to healthy organism (disease is dependant on external factors)
-should be reisolated from newly diseased patient

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8
Q

What factors determine whether a hsot bacteria interaction causes disease

A

Bacterial: route, number, virulence potential
host: host health, host genetics/genetics

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9
Q

Infection?

A

Pathogen is established in body

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10
Q

Disease?

A

infection produced signs and symptomsig

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11
Q

Signs vs symptoms?

A

Signs: observable by others
Symptoms: characteristis felt by patient

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12
Q

Asymptomatic carriage?

A

infection without disease

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13
Q

Opportunistic infection? +example

A

infection that would generally be cleared by system, but causes disease/death
e.g: pseudomonas in CF patients: thickened mucous in lungs prevents infection from being cleared

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14
Q

Secondary infection? +example

A

infection that develops in an individual already infected by another pathogen
e.g: TB in HIV patients

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15
Q

How can microbiomes affect susceptibility

A

colonization resistance (microbiome colony prevents pathogen from colonizing)

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16
Q

Steps of pathogenisis of bacterial diseases?

A
  1. Maintain a reservoir
  2. Be transported to the host
  3. Adhere to, colonize, and/or invade host
  4. Multiply or complete life cycles on or in host
  5. Evade host defenses
  6. Leave host and return to reservoir / enter new host
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17
Q

Reservoir? Types?

A

-habitat in which agent normally lives, grows and multiplies in
-humans (may or may not show effects of illness) animals or environment
specific to pathogen

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18
Q

Methods of transport pathogen to host

A

direct: direct contact & droplet spread
indirect: airborne, vehicle-borne, vector-borne

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19
Q

fomites?

A

inanimate objects in category of indirect, vehicule borne method of transport

20
Q

Adherence?

A

Mediated by adhesins

21
Q

Adhesins?

A

attach to specific strcutures: determine host susceptibility to pathogen

22
Q

Colonization?

A

site of microbial reproduction in host

23
Q

Invasion?

A

active penetration into or between host cells OR
passive penetration through unrelated means (bites, lesions…) or using host pathways of internalization (phagocytosis)

24
Q

Multiply or complete life cycles on or in host? what does it depend on

A

pathogen must find appropriate environment (for some, theres mutliple options for this)

25
Q

Evasion of host defenses by pathogen? types of defense (host) mechanisms and evasiont techniques

A

-complement system, phagocytosis, specific immune responses
-ex: bacteria capsule

26
Q

Leaving the host: why, how

A

-perpetuating the microbe
-passive mechanisms (feces, urine…) usually aided by symptoms

27
Q

Commensal strains vs pathogenic strains

A

commensal: rarely cause disease
pathogenic: can cause disease (different strains=different types of disease)

28
Q

Virulence factors and ability to cause disease (4)

A

Can improve:
-colonization or invasion of host
-ability to multiply or complete life cycles
-ability to evade hsot defenses
-ability to leave and enter new host

29
Q

Virulence factors (Molecular Koch’s postulates)?

A

-present in strains of bacteria causing disease (and vice-versa)
-disruption of gene reduces virulence
-reintroduction of gene restores virulence
-gene is expressed during infection

30
Q

Aquisition of virulence factors?

A

-transposons
-pathogenicity islands
-plasmids
-phages

31
Q

Examples of virulence factors?

A

-adhesins
-nutrient aquisition systems (ex: siderophores scavenge iron)
-capsule
-virulence asssociated secretion systems
-toxins

32
Q

Anti-virulence drugs example

A

receptor decoys (works against adhesins)

33
Q

T3SS? what, structure, bacteria type

A

virulence associated secretion system: injects bacterial proteins directly into host cells through syringe
flagellar basal body
gram (-) bacteria

34
Q

Types of toxins

A

Endotoxin: part of bacterial cell
Exotoxin: secreted

35
Q

Endotoxin: what, how is it toxic, what releases it, symptoms

A

LPS of gram (-) bacteria
Lipid A is toxic in high doses
Lysis of bacteria: increases host cell protein response, creating infmmation - can lead to sepsis (and fever)

36
Q

Characteristics of endotoxins

A

Toxic to host in high doses
No enzymatic activity
Heat stable

37
Q

Exotoxin example

A

Botulinum toxin (botox) - cleaves protein involved in neurotransmission from motor neurons to muscles (paralysis)

38
Q

Characteristic of exotoxins | inactivated toxin

A

highly toxic
easily inactivated by heat
inactivated: can be used to elicit immune response (antitoxin)

39
Q

Categories of exotoxins (2+2sub categories)

A

AB exotoxins: A=enzymatic activity B=cell binding/entry
membrane-disrupting exotoxins: poreforming or phospholipase

40
Q

Intoxications?

A

disese resulting from the entry of a specifc preformed toxin (very fast onset)

41
Q

Intoxication example:

A

Bacillus cereus: spore forming bacteria producing toxins that cause fast onset - grows in contaminated and improperly stored food
Vomiting

42
Q

EHEC? reservoir, infectious dose, method of transmission

A

enterohemmoragic E. coli
cattle (ground beef or contaminated manure)
as little as 10 organisms
T3SS: injectiong of Tir, becomes receptor

43
Q

EHEC symptoms and complications (HUC)

A

hemorrhagic colitis (bloody diarrhea)
0-20% of patients: hemolytic uremic syndrome
hemolytic anemia, platelet deficiency, kidney failure

44
Q

HUS complications

A

50%: chronic renal problems
25%: neurological symptoms
3-5%: death

45
Q

Shiga toxin: encoded in what, type/subunits,

A

EHEC (bacteriophages integrated in chromosome - prophage)
AB toxin: B-> glycolipids, A-> inhibits protein synthesis

46
Q

EHEC treatment

A

no specifc treatment, lysing bacteria increases risk of HUC
treat the symptoms, watch and wait

47
Q

EHEC prevention

A

handwashing, proper cooking of beef, safe food prep, pasteurization

MIMM 211 (7 decks)

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