02 - Pathogenic Mechanisms of Bacteria (Part I)

Question 1

(Host Defenses)

1-2. What are the two broad categories?

Answer 1

1. body surfaces
2. defenses of tissues and blood

Question 2

(Host Defenses)

(Body Surfaces)

1. What is the body’s first line of defense?
2. There are non-specific and specific induced defenses

Answer 2

1. skin and mucosal surface

Question 3

(Host Defenses)

(Skin)

1-3. What are the three defenses and their function?

Answer 3

1. dry, acidic (5), low temp (<37C) - limit bacterial growth
2. sloughing cells - remove bacteria
3. resident micro flora - compete for conolization

Question 4

look at this….

Answer 4

and this

Question 5

(Host Defenses)

(Mucous Membrane)

1. mucus secreted by what?
2. acts as a lubricant and a physical barrier that does what?
3. Mucus contains which immunoglobin?

Answer 5

1. goblet cells
2. traps bacteria before they reach membrane itself
3. immunoglobin A

Question 6

(Mucus also contains substances that either kill bacteria or inhibit their growth)

1. Which splits muramic acid linkage in bacteria (esp G+), and degrades PTG?
2. Which is found in milk and many mucosal secretions such as tears and saliva?
3. antimicrobial agent in milk, saliva, and tears.. toxic to many bacteria
4. Which of these is a protein that binds with high affinity with Iron? why is this important?

Answer 6

1. lysozyme
2. lactoferrin
3. lacto peroxidase
4. lactoferrin; iron is essential for bacteria… can’t compete with lactoferrin

Question 7

(GALT/MALT)

1. what do these stand for?
2. What do they do?

Answer 7

1. gastrointesinal/mucosa associated lymphoid tissue
2. produce secretory antibody - prevent bacterial adherence to mucosal cells

Question 8

look at this…

Answer 8

Question 9

Question 10

(Bacteria have developed the ability of surviving inside PMN’s or Macrophages)

1-4. What are the four ways?

Answer 10

1. escape phagosome before fusion with lysosome
2. prevent phagosome-lysosome fusion
3. prevent acidification
4. reduce toxic compound effectiveness (catalase and superoxide dismutase that detoxify reactive O2)

Question 11

(Terms to Remember)

1. Disesase causing microorganisms
2. the physiological processes involved in the generation of clinical signs of disease
3. the capacity of a microbe to cause disease
4. ability of a microbe to cause disease efficiently or inefficiently – also refers to degree of pathogenecity
5. component of a pathogen that contributes to tis disease producing potential (ie toxins and surface molecules)

Answer 11

1. Pathogens (often there is a cooperation amongst pathogens – synergism and oppotunists)
2. pathogenesis
3. pathogenecitiy
4. virulence
5. virulence factor

Question 12

(Koch’s Postulates)

(four criteria designed to establish causal relationship between causative microbe and a disease)

1-4. What are they?

Answer 12

1. Must always be found in organism with disease - but not in healthy ones
2. Must be isolated from diseased and grown in culture
3. organism must initiate disease when put in new organism
4. should be re-isolated from experimentally infected animals

Question 13

just read this…

Question 14

(Virulence)

1. is the degree of pathogenecity within a group of species of microorganisms or viruses
2. as indicated by what?
3. The pathogenic capacity of an organism is determined by what?

Answer 14

2. case fatality rate or ability to invade host tissues
3. its virulence factors

Question 15

(Methods By which pathogens cause disease)

1-5. name them

Answer 15

1. adhesion
2. colonization
3. invasion
4. immune response inhibitors
5. toxins

Question 16

(Bacteria (ex salmonella typhimurium) can penetrate the gut epithelial route by three routes)

1-3. What are they…

Answer 16

1. adheres/enters M cells then kills with apoptosis… then infects macrophages and gut epithelial cells
2. adherence of bacteria fimbriae to luminal epithelial surface
3. dendrites can be infected by salmonella in the lumen

(see next slide)

Question 17

Answer 17

Question 18

(Virulence Factors)

1-2. Divided into what two major categories

Answer 18

1. factors that promote bacterial colonization and invasion
2. factors that cause damage to host

Question 19

(Factors that promote conlonization and survival of bacteria)

1. once bacteria reaches host, must do what to colonize them…
2. best mechanism of adherence is attachment mediated by what?
3. what mediates adherence of bacteria on the host cell surface

Answer 19

1. adhere
2. rod shaped protein structure called Pili or fimbriae
3. tip of the pilus

Question 20

check this out

a summary of what is to come I believe

Question 21

(Adhesins)

1. what are these?
2. mediate what?

Answer 21

1. cell surface proteins that are important for adherence
2. tighter binding of bacteria to host cell

Question 22

(Invasins)

1. Some bacteria have evolved mechanisms for entering host cells that are not naturally phagocytic
2. attach and cause changes in what to enter?
3. bacterial surface proteins that provoke phagocytic ingestion of the bacteria by the host cells are called what?

Answer 22

2. cytoskeleton

3. invasins

Question 23

he didn’t talk about this much

Answer 23

here we have the capsule

Question 24

1. How do capsules help bacteria survive?

Answer 24

1. protect from hosts inflammatory response (complement activation and phagocyte-mediated killing)

Question 25

(How Siderophores help bacterial survival)

1. are low molecular weight compounds that do what?
2. excreted into medium by what?
3. Iron is essential for bacteria and its conc in nature is quite low

Answer 25

1. chelate iron with high affinity
2. by bacteria (iron-siderophore complex is taken up by special siderophore receptors on bacterial surface)