Gram-negative Pathogens and Mucosal Surfaces

Question 1

What is a mucosal surface?

Answer 1

A surface that interacts with air and has associated glands for excreting mucous.
Found in mouth, GI tract, respiratory, etc

Question 2

Defenses of muscosal surfaces

Answer 2

Innate immunity
Adaptive immunity
Nonspecific barrier defenses

Question 3

Transmission of Gram-negative pathogens

Answer 3

Feces to mouth, via the “7 F’s”

feces, food, fluids, fingers, flies, fomites, fornication

Question 4

Inoculum size

Answer 4

the number of organisms required to start an infection. varies from species to species

Question 5

Natural barrier defensces of the GI tract

Answer 5

Acidity (ranges from ~2-9)
Motility (stuff moves)
Mucous layer and underlying glycocalyx
Tight junctions

Question 6

Secretory antimicrobial compounds (Innate Immunity)

Answer 6

Lysozyme
Lactoferrin
Cathelcidin
Defensins

Question 7

Lysozyme

Answer 7

Cleaves linkages between N-acetylmuramic acid and N-acetylglucosamine, degrading peptidoglycan
Better at degrading Gram+ than Gram-

Question 8

Lactoferrin

Answer 8

Bacteriostatic effects via sequestering iron

Question 9

Cathelcidin

Answer 9

Distrupts bacterian membranes on Gram+ and Gram-

Embeds within lipid bilayer, creating a pore, leading to breakdown

Question 10

Defensins

Answer 10

Creates pores in microbes. 2 types:
a-defensins (produced by neutrophils and paneth cells)
B-defensins (produced by epithelial cells)

Question 11

Hoe do bacteria overcome innate barrier defenses

Answer 11

Acid resistance
Fimbrae/Pilli
Bacterial structures

Question 12

Negative side to inflamatory responses at mucosal surfaces

Answer 12

Inflammatory cytokines (such as TNF-a) can disrupt tight junctions between epithelial cells