Host/Parasite Relatioships

Question 1

What is a commensal organism?

Answer 1

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

Question 2

What is a mutual organism?

Answer 2

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

Question 3

Shelter + food (nutrients) =

Answer 3

niche

Question 4

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

Answer 4

True

Question 5

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

Answer 5

sterile

Question 6

What are all the different colonized sites?

Answer 6

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

Question 7

What are normally sterile?

Answer 7

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

Question 8

When do neonates start to become colonized with microbiota?

Answer 8

vaginal delivery –> during birth

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

Question 9

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

Answer 9

resident

Question 10

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

Answer 10

transient

Question 11

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

Answer 11

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

Question 12

Is Staphyloccous epidermis an example of resident or transient microbiota?

Answer 12

resident - normally found in skin, nose and ears

Question 13

What kind of bacteria is Staph. epidermidis?

Answer 13

Gram (+) cocci, in clusters

Question 14

Infections with Staph. epidermidis is generally associated with what?

Answer 14

prosthetic devices and intravenous catheters

Question 15

What resident bacteria is a common contaminant of blood cultures?

Answer 15

Staph. epidermidis

Question 16

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

Answer 16

transient

Question 17

What kind of bacteria is GAS?

Answer 17

Gram (+) cocci, in chains

Question 18

Where does GAS transiently colonize?

Answer 18

oropharynx of children and young adults in absence of clinical disease

Question 19

What is the causative agent of strep throat?

Answer 19

GAS

Question 20

What’s the definition of pathogens?

Answer 20

any microorganism that has the capability to cause disease

Question 21

What are the two kinds of pathogens?

Answer 21

1) strict pathogens

2) opportunistic pathogens

Question 22

Which type of pathogens is always associated with disease?

Answer 22

strict pathogens

Question 23

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

Answer 23

opportunistic pathogens

Question 24

How do opportunistic pathogens cause disease?

Answer 24

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

Question 25

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

Answer 25

opportunistic

Question 26

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

Answer 26

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

Question 27

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

Answer 27

pathogenicity

Question 28

What is a measurement of pathogenicity?

Answer 28

virulence

Question 29

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

Answer 29

virulence factors

Question 30

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

Answer 30

carrier

Question 31

What is significant about carriers?

Answer 31

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

Question 32

What are some events associated with infection (3)?

Answer 32

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

Question 33

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

Answer 33

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

Question 34

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

Answer 34

adhesion

Question 35

Specific adhesin and receptor combinations often define ____

Answer 35

tropism

Question 36

What are biofilms?

Answer 36

bacteria encased in a exoploymeric substance of their own making

Question 37

Are most bacteria planktonic or sessile?

Answer 37

sessile

Question 38

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

Answer 38

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

Question 39

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

Answer 39

True

Question 40

What's an example of endotoxin?

Answer 40

lipid A of LPS

Question 41

What are exotoxins?

Answer 41

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

Question 42

What do A and B mean in AB toxins?

Answer 42

``` A = active B = binding ```

Question 43

What are superantigens?

Answer 43

they bind both TCR and MHC class II without an antigen

Question 44

Why are capsules a mechanism for escaping host defenses?

Answer 44

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

Question 45

What is antigenic mimicry?

Answer 45

bacteria can produce compounds the host sees as self

Question 46

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

Answer 46

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

Question 47

How does inactivation antibody work against host defense?

Answer 47

secretion of proteases that degrade specific antibody isotypes

Question 48

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

Answer 48

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

Question 49

How do bacteria escape phagocytic clearance?

Answer 49

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

Question 50

Why might bacteria hold off on producing virulence factors?

Answer 50

1) very energy intensive | 2) they elicit host immune responses

Question 51

Do bacteria constituitvely express virulence factors?

Answer 51

no

Question 52

Can bacteria sense their environment?

Answer 52

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

Question 53

What is quorum sensing?

Answer 53

a way for bacteria to sense the size of their population

Question 54

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

Answer 54

autoinducers - species specific signals - universal signal

Question 55

Is peptidoglycan considered a virulence factor?

Answer 55

no