Host parasite relationships

Question 1

What is the causative agent of strep throat?

Answer 1

Streptococcus pyogens (Group A strep)

Question 2

What are opportunistic pathogens?

Answer 2

1. Tend to be members of normal microbiota2. Take advantage of preexisting conditions, such as immunosuppression to grow and cause disease

Question 3

What is pathogenicity?

Answer 3

Ability of a microorganism to cause disease

Question 4

What is virulence?

Answer 4

Measurement of pathogenicity

Question 5

What is a carrier?

Answer 5

1. Asymptomatic individual who is host to a pathogen 2. Has the potential to transmit pathogen to others3. Condition of being a carrier may be transient or (semi) permanent

Question 6

What are the events associated with infection?

Answer 6

1. Entry into host2. Adhesion, colonization, pathogenic action 3. Escaping host defense

Question 7

How is adhesion obtained?

Answer 7

1. Adhesins, or attachment proteins, are often but not always associated with bacterial pili2. Specific adhesin and receptor combinations often define tropism

Question 8

What are biofilms?

Answer 8

1. Bacteria encased in an exopolymeric substance of their own making2. Altered metabolism, usually slower3. Increased antibiotic resistance4. Increased genetic exchange5. Resistance to disinfection (decreased diffusion, increased organic matter)

Question 9

What characterizes pathogenic action of bacteria?

Answer 9

1. Invasion into cells (hijack host cell machinery, modulate maturation of phagosome to promote survival)2. Dissemination (can cause disease at location far from initial infection site)

Question 10

What are exotoxins?

Answer 10

1. Bacterial products that directly harm tissues or lead to destructive biologic activites2. Cytolytic enzymes3. Receptor binding proteins that initiate toxic reactions)4. A = active5. B = binding

Question 11

What are superantigens?

Answer 11

1. Bind both TCRs and MHC 2 without requiring an antigen2. Activation of large amount of cytokines with life threatening autoimmune type response

Question 12

What are characteristics of encapsulation?

Answer 12

1. Generally a poor antigen2. Masks more antigenic epitopes on bacterial surface3. Prevent binding of antibody or complement

Question 13

What are characteristics of antigenic mimicry?

Answer 13

Bacteria can produce compounds the host sees as self

Question 14

What are characteristics of antigenic shift?

Answer 14

1. Quickly change antigenic makeup of proteins on cell surface2. Moving target

Question 15

What are characteristics of inactivation antibody?

Answer 15

Secretion of proteases that degrade specific antibody isotypes

Question 16

What are characteristics of resistance to complement mediated killing?

Answer 16

1. Limited access to membrane2. Degradation of complement components

Question 17

How are virulence factors regulated?

Answer 17

1. Quorum sensing2. Regulation of gene expression in response to population size3. A way for bacteria to act as a multicellular group of organisms as opposed to individuals carrying out a genetic program