Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biosci 349: Biomedial Microbiology > Microbial Pathogens > Flashcards

Microbial Pathogens Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What are the most common bacteria on our skin?

A

Staphylococcus, Streptococcus, Corynebacterium

They colonise warm, sheltered places and metabolise sweat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Biofilms, 300 to 500 cells thick on teeth are composed of mainly…

A

Streptococcus sanguis and Streptococcus mutans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Bacteria in the gut are essential for..

A

Breaking down carbohydrates, producing essential nutrients (Vit K & B12) and crowding out harmful bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How much of our genome consists of fossil viruses?

A

About 1/12

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the points of Koch’s Postulate?

A
  1. The microorganism must always be found in similarly diseased animals, but not in healthy ones.
  2. The microorganism must be isolated from a diseased animal and grown in pure culture.
  3. The isolated microorganism must cause the original disease when inoculated in a susceptible host
  4. The microorganism must be re-isolated from the experimentally infected animals.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the issues with Koch’s Postulate?

A
  1. Animal may be asymptomatically carrying
  2. Some microorganisms cannot/are hard to grow in culture
  3. The isolated microorganism should cause original disease upon inoculation but does not always
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Symbiosis

A

Organisms live together in close association

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Mutualism

A

Beneficial to both symbionts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Neutralism

A

Neither symbiont is affected by the relationship

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Commensalism

A

Beneficial to only one symbiont

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Parasitism

A

Harmful to one (host), beneficial to other (parasite)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Synergism

A

Two or more microorganisms team up to cause disease. Also called polymicrobial infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Pathogen

A

Microorganism that causes diease (<3% of all)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Opportunistic Pathogen

A

Has the potential to cause disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the periods in the course of an infectious disease?

A

Incubation Period - time between infection and onset of symptoms
Prodromal Period - patient feels out of sorts, but experiences no symptoms
Illness - experience of symptoms associated with the disease
Convalescent Period - time during which the patient recovers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the types of human carriers of disease?

A

Passive Carrier - carries pathogen but has never had disease symptoms
Incubatory Carrier - patient is in incubation period (asymptomatic)
Convalescent Carrier - patient recovering from disease, but still carrying pathogen
Active Carrier - patient has completely recovered, but still carries pathogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the 6 types of infection?

A

Localised - pathogens are contained at the site of infection
Systemic - pathogen spreads throughout the body
Acute - rapid onset, rapid recovery
Chronic - slow onset, slow recovery
Latent - pathogen not completely eradicated after recovery and can cause symptoms in future
Secondary - disease that follows primary infection

18
Q

What is the difference between an infectious disease and microbial intoxication?

A

In an infectious disease a pathogen colonises hos body and causes disease. In microbial intoxication a pathogen is produced in vitro and toxins are ingested to cause disease - this is often more rapid in onset and recovery than the former

19
Q

Steps in pathogenesis of infectious disease

A
  1. Entry
  2. Attachment
  3. Multiplication
  4. Invasion or spread
  5. Evasion of host defenses
  6. Damage to host tissue
20
Q

What are some virulence factors

A
  1. Promote attachment to host cells (adhesins)
  2. Help bacterium to enter host cell (invasins)
  3. Damage host cell or tissue (e.g. cytolysins)
  4. Over-stimulate immune response (immunopathogenic factors)
  5. Mediate immune evasion
21
Q

What are some immune evasion factors?

A
  1. Capsules (prevent opsonisation and phagocytosis)
  2. Destruction of phagocytes
  3. Inhibition of phagocyte chemotaxis
  4. Inhibition of phagocytosis
  5. Destruction of complement factors
  6. Destruction of immunoglobulins
  7. Intracellular replication
22
Q

What are some reasons that disease isn’t always observed?

A
  1. Unable to grow at site of contact
  2. Absence of colonising host receptors
  3. Antibacterial factors (e.g. lysozyme in tears)
  4. Microbial antagonism - indigenous bacteria use all nutrients/antibacterial factors
  5. Health status
  6. Immunity
  7. Elimination by immune system
23
Q

Bacterial that are ingested

A

Salmonella, Campylobacter, Shigella, E. Coli, Vibrio

24
Q

Bacterial that are inhalated

A

Legionella, Streptococcus, M. pneumoniae, Bordetella

25
Q

Bacterial that infect via trauma

A

Clostridium tetani

26
Q

Bacterial that infect via needlestick

A

Staphylococcus aureus, Pseudomonas

27
Q

Bacterial that infect via arthropod bite

A

Rickettsia, Coxiella, Borrelia, Yersinia pestis, Francisella

28
Q

Bacterial that infect via sexual transmission

A

Neisseria gonorrhoeae, Chlamydia trachomatis, Treponema pallidum

29
Q

What are 4 basic mechanisms of immune evasion?

A
  1. Disguise - surface molecules, antigenic variation
  2. Hide - invasion of host cells, biofilms)
  3. Fool - de-regulating immune responses
  4. Attack - destruction of immune components
30
Q

what are some examples of CAMPs?

A 
alpha-Defensin hNP-1
beta-Defensin hBD1
Cathelicidin LL-37
Thrombocidin TC1
Dermcidin
31
Q

What are some antimicrobial host factors and what charge are they?

A
  • Positively charged
  • Antimicrobial peptides
  • Lactoferrin
  • Lysozyme
  • Myeloperoxidase
32
Q

What are some features of the bacterial cell envelope and what charge are they?

A
  • Negatively charged
  • Peptidoglycans
  • Teichoic Acids
  • Lipoteichoic Acids
  • Lipid A
  • LPS
33
Q

What are 4 mechisms of CAMP resistance in bacteria?

A
  1. Repulsion of CAMP (Modification of TA or Lipia A - Staph, Strep, Salmonella, Pseudomonas)
  2. Extrusion of CAMP (MtrCDE efflux pump - Neisseria)
  3. Neutralisation of CAMP (Staphylokinase, SIC - Staph, Strep)
  4. Cleavage of CAMP (PgtE proteases - E. Coli, Salmonella)
34
Q

What are the 3 forms of complement evasion by bacteria?

A
  1. Modulation or inhibition of complement proteins
  2. Inactivation by enzymatic degradation
  3. Recruitment or mimicking of complement regulators
35
Q

What are some ways bacteria modulate or inhibit complement proteins?

A
  1. Staphylococcal complement Inhibitor (SCIN) binds to C3 convertases and inhibits its activation
  2. Streptococcal inhibitor of complement (SIC) binds to C5c-C7/C8 and prevents the formation of MAC. MAC is ineffective against gram positive bacteria like Strep so this mechanism is confusing
  3. Staphylococcal protein A (SpA) is found on the bacterial cell surface and binds the Fc regin of IgG which prevents opsonisation and the classical pathway
  4. Chemotaxis inhibitory protein of Staph Aureus (CHIP) binds to C5a receptor and inhibits its chemotactic signalling
36
Q

What are some ways bacteria inactivate complement by enzymatic degradation?

A
  1. Pseudomonas proteases cleave C3 and prevent C3b opsonisation
  2. Pseudomonas elastase cleaves IgG and C1q which prevents initiation of the classical pathway
  3. C5a peptidase (Strep, Serriatia) cleaves C5a and prevents neutrophil chemotaxis
37
Q

What does Staphylokinase (Sak) and Streptokinase both do?

A

They convert plasminogen to plasmin, which cleaves TgG , C3b - creating a capsule around the bacterium so it looks like “self”

38
Q

What are some ways bacteria recuit or mimic complement regulators?

A
  1. C4 binding protein (C$BP) accelerates decay of C3 convertases and is recruited by…
    Strep (M protein)
    E. coli (OmpA)
    Neisseria gonorrhoeae (porin)
  2. Factor H (FH) degrades C3b and accelerates decay of AP C3 cnvertases. It is recruited by Strep (M protein) and Haemophilus influenza
39
Q

How is LPS used to evade the immune system?

A
  1. It can be modified with sialic acid. Factor H will prevent opsonisation of sialic acidcontaining surfaces (because our cells have this) - many strains of Neisseria have this
  2. Long side chains (O antigen) so phagocytes can’t physically reach receptors (C3b) to target the bacterium. Pseudomonas does this.
40
Q

What is an example of a bacteria that uses a hyaluronic acid capsule to evade the immune system

A

Streptococcus pyogenes

41
Q

What are some ways that bacteria evade destruction in phagocytes?

A
  1. Blocking the proton pump (ureC) which prevents acidification.
  2. Blocking lysosome fusion with the phagosome which arrests phagosome maturation. M. tuberculosis does this.
  3. Produce a catalase that conversts H2O2 to oxygen and water
  4. Produce a phenolic glycolipid to prevent attack by ROI. Mycobacterium do this.
  5. Make a pore in the phagosome for bacterium to escape to cytosol through. Done by cytolysins, e.g. listerolysin
42
Q

How and why do bacteria invade non-phagocytic cells?

A 
For shelter
Uptake induced by bacteria by inducing a reorganisation of the actin cytoskeleton of the host cell
Some bacteria inject toxins (effectors)
T3SS - Type 3 secretion system
E. Coli, Shigella, Salmonella

Biosci 349: Biomedial Microbiology (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions