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Microbiology Exam 1 > Host/Parasite Relatioships > Flashcards

Host/Parasite Relatioships Flashcards

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Biology 101 flashcards
1
Q

What is a commensal organism?

A

one that lives inside host but neither benefit or harm each other

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2
Q

What is a mutual organism?

A

one that lives inside host and both parties benefit from each other (such as colon)

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3
Q

Shelter + food (nutrients) =

A

niche

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4
Q

True or False. Normal microflora can be beneficial to host by producing toxins that harm pathogenic microorganisms

A

True

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5
Q

Is a fetus sterile or does it contain microbiota from mother?

A

sterile

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6
Q

What are all the different colonized sites?

A

1) skin
2) mucosa
3) intestine
4) urogenital tract

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7
Q

What are normally sterile?

A

1) internal organs and tissue
2) cervix
3) middle ear
4) urinary bladder (becoming less true)

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8
Q

When do neonates start to become colonized with microbiota?

A

vaginal delivery –> during birth

C-section delivery –> after birth as it’s getting handled by people

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9
Q

Long-term members of the body’s normal microbiota is known as _____

A

resident

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10
Q

Organisms that attempt to colonize the body but are unable to remain are known as ____

A

transient

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11
Q

Transient organisms that are unable to remain in the body can be due to ….(3)

A

1) competition from resident microbiota
2) elimination by body’s immune sys
3) physical or chemical changes within body that discourage growth

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12
Q

Is Staphyloccous epidermis an example of resident or transient microbiota?

A

resident - normally found in skin, nose and ears

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13
Q

What kind of bacteria is Staph. epidermidis?

A

Gram (+) cocci, in clusters

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14
Q

Infections with Staph. epidermidis is generally associated with what?

A

prosthetic devices and intravenous catheters

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15
Q

What resident bacteria is a common contaminant of blood cultures?

A

Staph. epidermidis

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16
Q

Is GAS (group A Streptococcus pyogenes) an example of resident or transient microbiota?

A

transient

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17
Q

What kind of bacteria is GAS?

A

Gram (+) cocci, in chains

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18
Q

Where does GAS transiently colonize?

A

oropharynx of children and young adults in absence of clinical disease

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19
Q

What is the causative agent of strep throat?

A

GAS

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20
Q

What’s the definition of pathogens?

A

any microorganism that has the capability to cause disease

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21
Q

What are the two kinds of pathogens?

A

1) strict pathogens

2) opportunistic pathogens

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22
Q

Which type of pathogens is always associated with disease?

A

strict pathogens

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23
Q

Which type of pathogens tend to be members of normal microbiota?

A

opportunistic pathogens

24
Q

How do opportunistic pathogens cause disease?

A

they take advantage of preexisting conditions such as immunosuppression to grow and cause disease

25
Q

Are most infectious diseases of humans caused by strict or opportunistic pathogens?

A

opportunistic

26
Q

What are the different types of opportunistic infections (7)?

A

1) contamination of intravenous catheters
2) wound/ surgical site infections
3) bacterial endocarditis
4) aspiration pneumonia
5) urinary tract infections
6) pseudomembrane colitis
7) otitis media

27
Q

What is known as the ability of a microorganism to cause disease?

A

pathogenicity

28
Q

What is a measurement of pathogenicity?

A

virulence

29
Q

What are factors produced by organisms that enable it to infect, cause disease, and/or kill a host, such as toxins?

A

virulence factors

30
Q

An asymptomatic individual who is host to a pathogen is known as ____

A

carrier

31
Q

What is significant about carriers?

A

they have the potential to transmit the pathogen to others. condition may be transient or (semi) permanent

32
Q

What are some events associated with infection (3)?

A

1) entry into the host
2) adhesion, colonization and pathogenic action of bacteria
3) mechanisms for escaping host defenses

33
Q

What are some barriers that are in place to protect pathogen entry (6)?

A

1) mechanical (skin)
2) enzymatic (lysozyme)
3) chemical (acidic pH)
4) immunity
5) commensals (niche environments)
6) physical (sheer forces such as showers)

34
Q

The binding of the bacterial adhesin to the host cell surface is known as the process of ____

A

adhesion

35
Q

Specific adhesin and receptor combinations often define ____

A

tropism

36
Q

What are biofilms?

A

bacteria encased in a exoploymeric substance of their own making

37
Q

Are most bacteria planktonic or sessile?

A

sessile

38
Q

What are some benefits to biofilms (for the bacteria)?

A

1) increased resistance to antibiotics
2) increased genetic exchange
3) resistant to disinfection

39
Q

True or False. Most chronic bacterial infections (some acute) have a biofilm component

A

True

40
Q

What’s an example of endotoxin?

A

lipid A of LPS

41
Q

What are exotoxins?

A

bacterial products that directly harms tissue or lead to destructive biologic activities

42
Q

What do A and B mean in AB toxins?

A 
A = active
B = binding
43
Q

What are superantigens?

A

they bind both TCR and MHC class II without an antigen

44
Q

Why are capsules a mechanism for escaping host defenses?

A

they mask antigenic epitopes on bacterial surface, prevent binding of Ab or complement

45
Q

What is antigenic mimicry?

A

bacteria can produce compounds the host sees as self

46
Q

How is antigenic variation/shift a mechanism for escaping host defenses?

A

some bacteria can quickly change the antigenic make up of proteins on their cell surface

47
Q

How does inactivation antibody work against host defense?

A

secretion of proteases that degrade specific antibody isotypes

48
Q

How do some bacteria deal with complement-mediated killing by host?

A

1) limiting access to the membrane by either capsule or long O-antigen on LPS
2) degradation of components of complement

49
Q

How do bacteria escape phagocytic clearance?

A

1) inhibit opsonization
2) inhibit chemotaxis
3) kill phagocyte
4) inhibit lysosomal fusion
5) escape from lysosome
6) resistant antibacterial lysosomal action

50
Q

Why might bacteria hold off on producing virulence factors?

A

1) very energy intensive

2) they elicit host immune responses

51
Q

Do bacteria constituitvely express virulence factors?

A

no

52
Q

Can bacteria sense their environment?

A

yes: light, pH, nutrients, waste products, host molecules

53
Q

What is quorum sensing?

A

a way for bacteria to sense the size of their population

54
Q

What kind of signals do bacteria give off to each other?

A

autoinducers

  • species specific signals
  • universal signal
55
Q

Is peptidoglycan considered a virulence factor?

A

no

Microbiology Exam 1 (10 decks)

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