Lecture 3 - Pathogenic Mechs

Question 1

There are two types of entry:

1. _____ (Taken into the body without crossing epithelial barriers –> i.e. inhalation or ingestion.)
2. Penetration (crossing through the epithelial barrier directly.)

Answer 1

Ingress

Question 2

What are some things that aid with the spread and colonization of microbes?

Answer 2

1. Physical environment is favorable for growth.
2. Expression of adhesin molecules by the microbe to facilitate binding to host cells/surfaces.
3. Biofilms –> slimy polysaccharide substance that helps microbes resist host defenses.

Question 3

C3b is an important molecule as part of the _____ immune response as it binds tightly to _____, resulting in opsonization (which, itself, aids in phagocytosis.) ____ carry out a similar function by binding antigenic epitopes and are part of the _____ immune response.

Answer 3

Innate

LPS

Adaptive

Question 4

One of the ways Staph. Aureus (the only staph that produces this) evades phagocytosis is through its production of ______, which binds to the ____ region of Abs, thus preventing them from binding their receptors on phagocytes.

Answer 4

Protein A

Fc

Question 5

M. _______ can prevent the fusion of phagosomes with _____ after they have been taken up by the phagocyte.

Answer 5

M. Tuberculosis

Lysosomes

Question 6

One of the host defenses against infection in mucous layers in secretory ____. However, bacteria of the _____ genus as well as S. _____ have a secretory ______ protease that helps them evade this Ab.

Answer 6

IgA

Neisseria

S. Pneumoniae

IgA protease

Question 7

_____ variation is a way in which pathogens avoid the host immune system. This causes symptomatic/asymptomatic cycles in the host as the immune response kills off the majority of the pathogen, but the few that survived eventually grow in number to the point where the host becomes symptomatic again. This typically occurs when bacteria switch the expression of their surface proteins.

Answer 7

Antigenic

Question 8

_____toxins are intrinsic cell envelope components while _____toxins are proteins that some bacteria make.

Answer 8

Endotxins

Exotoxins

Question 9

There are 3 broad classes of exotoxins:

1. A/B type toxins
2. _____ disrupting toxins
3. _____antigens

Answer 9

Membrane disrupting

Superantigens

Question 10

In A/B type toxins, the A subunit is _____ while the B subunit is _____ (binds the A subunit and host cells.) Once bound to the host cell, the ____ subunit enters to carry out its function.

Answer 10

Enzymatic

Binding

A

Question 11

Some A subunits have _____ase activity, resulting in the activation of ____cyclase (increase in cAMP production) or inactivation of _____ (thereby blocking translation.)

Answer 11

NADase activity

Andenylyl cyclase

EF2

Question 12

Some exotoxins intercalate in the plasma membrane of host cells, forming pores, allowing _____ to flow out, and _____ to flow in.

Answer 12

Ions

Water

Question 13

Other exotoxins cleave the _____ head of the phospholipids in the host cell plasma membrane.

Answer 13

Phosphate

Question 14

______ bind to TCRs via a non-______ interaction, causing a massive production of _______.

Answer 14

Superantigens

non-specific

Cytotkines

Question 15

C. Diptheriae is a gram _____ bacillus that colonizes the throat and ______. It produces a ______ (grey mucoid coat.) Diptheria toxin can affect the _____ and peripheral nerves if it is carried through the blood.

Answer 15

Positive

Nasopharynx

Pseudomembrane

Heart

Question 16

Diptheria toxin is an ___/___ type toxin that ADP-_____ EF2, blocking translation.

Answer 16

A/B type toxin

ADP-Ribosylates EF2

Question 17

Treatment involves a combination of antitoxin and ______ (to kill the bacteria.)

Answer 17

Antibiotics

Question 18

B. Pertussis is a small gram _____ coccobacillus. It grows slowly, colonizing region between _____ and _____. Symptoms begin like cold symptoms and progress to the paroxysnal stage characterized by intense bouts of ______ interrupted by “______.”

Answer 18

Negative

Airway and Lungs

Coughing

“Whooping”

Question 19

There are 3 virulence factors for B. Pertussis, one of which is an adhesin. The other 2 are ___/___ type toxins (one of which is an _____ cyclase toxin and the other is Pertussis toxin which stimulates the host cell _____ cyclase by inhibiting Gi via ADP-ribosylation.)

Answer 19

A/B type toxins

Adenylyl cyclase toxin

Adenylyl cyclase

Question 20

Treatment for B. Pertussis involves administration of ______ and adequate O2 support.

Answer 20

Antibiotics

Question 21

P. Aeruginosa is a gram ____ bacillus that can grow in almost all media. Colonies have a _____ odor and a blue-green pigment. It’s an obligate ______ (requires O2.) It is considered an _______ pathogen (infects immune compromised patients) and can cause “swimmer’s ear” (otitis externa.)

Answer 21

Negative

Fruity

Aerobe

Opportunistic pathogen

Question 22

P. aeruginosa virulence fcators include ______, required for initial colonization, and 2 simple A/b type toxins. It also forms a biofilm.

Answer 22

Pili

Question 23

Treatment of P. aeruginosa involves aggressive use of two antibiotics because of its _____ factors.

Answer 23

Resistance