Lecture 3 - ESKAPE Pathogens

Question 1

describe gram positive bacteria

Answer 1

thick PG layer

Question 2

describe gram negative bacteria

Answer 2

has thin PG layer, outer membrane, and lipoproteins

Question 3

how can we determine if bacteria is positive or negative in the clinic?

Answer 3

gram stain:
- gram positive = purple
- gram negative = colourless

Question 4

what shape are most gram positive bacteria?

Answer 4

cocci

Question 5

what shape are most gram negative bacteria?

Answer 5

rod-shaped

Question 6

is mycobacterium tuberculosis gram pos or neg?

Answer 6

neither!

Question 7

what stain can we use to determine mycobacterium tuberculosis? why?

Answer 7

use acid-fast stain bc has mycolic acids on the cell surface

Question 8

why is M. tb often misdiagnosed?

Answer 8

it is rare and false positives for gram pos are common

Question 9

how are our immune systems activated by bacteria?

Answer 9

surface markers on bacteria activate TLRs

Question 10

where are TLRs found?

Answer 10

mainly innate immune cells like DCs and macrophages

also non-immune cells like fibroblasts and epithelial cells

Question 11

what do we do when our immune system can’t control bacteria?

Answer 11

use antibiotics to clear the infection

Question 12

where do many antibiotics come from? why?

Answer 12

antibiotics often come from other microbes and were originally used to allow for competition in the environment

Question 13

how do microbes develop resistance via environment?

Answer 13

microbes take up helpful genes from other microbes in environment to develop resistance

Question 14

7 antibiotics that are bacteriocidal

Answer 14

1. B-lactams
2. aminoglycosides
3. glycopeptides
4. ansamycins
5. quinolones
6. streptogramins
7. lipopeptides

Question 15

5 antibiotics that are bacteriotatic

Answer 15

1. sulfonamides
2. chloramphenicol
3. tetracyclines
4. macrolides
5. oxazolidinones

Question 16

what is the only class of antibiotics that works on gram negative only?

Answer 16

aminoglycosides

Question 17

what are the only 3 classes of antibiotics that work on gram positive only?

Answer 17

1. macrolides
2. lincosamides
3. glycopeptides

Question 18

how many days is the normal course of antibiotics?

Answer 18

7-10 days

Question 19

how long is the normal course of antimycobacterials for M. tb?

Answer 19

2 antibiotics for 6 months and 2 additional antibiotics for the first 2 months

Question 20

what antibiotics are used for M. tb infection?

Answer 20

isoniazid and rifampicin for 6 months

pyrazinamide and ethambutol for the first 2 months

Question 21

what is the controversy with antibiotic use?

Answer 21

ppl say antibiotics affect the microbiota and changes in the microbiota is linked to many diseases so some ppl don’t take antibiotics even when they need them

Question 22

what is dysbiosis?

Answer 22

how changes in the microbiota affect the rest of the body and link to disease, etc.

Question 23

4 mechanisms of antibiotic resistance

Answer 23

1. efflux pumps
2. immunity and bypass
3. target modification
4. inactivating enzymes

Question 24

what are the 6 ESKAPE pathogens?

Answer 24

E = escherichia
S = staphylococcus
K = klebsiella
A = acinetobacter
P = pseudomonas
E = enterococcus

Question 25

where are do ESKAPE infections occur?

Answer 25

nocosomial –> acquire from hospital

Question 26

describe how antibiotic resistance has spread from farming

Answer 26

• livestock given antibiotics to make them bigger
• we eat the meat and acquire the resistant genes

Question 27

what bacteria is the leading cause of death by infectious diseases in the western world?

Answer 27

Staphylococcus aureus

Question 28

is Staphylococcus aureus gram pos or neg?

Answer 28

Staphylococcus aureus is gram pos

Question 29

what makes Staphylococcus aureus so dangerous?

Answer 29

it has evolved many ways to evade the innate immune system

Question 30

what did people originally believe about Staphylococcus aureus infection? why?

Answer 30

originally thought it was extracellular pathogen bc appears as nodules in the kidney

Question 31

is Staphylococcus aureus extracellular?

Answer 31

in vitro data has shown that it can survive intracellularly within phagocytic cells like neutrophils and phagocytes (kupffer cells)

then burst to become the extracellular nodes on kidney

Question 32

why does Staphylococcus aureus become nodes in the kidney?

Answer 32

Kupffer cells burst when the bacteria builds up and then moves to the kidney to form the nodes

Question 33

why do Kupffer cells take up S. aureus?

Answer 33

Kupffer cells are strategically located so they can use special mechanisms to capture bacteria from the high shear forces in the bloodstream

they also uniquely express CRIg

Question 34

what imaging method can be used to detect the bacteria in KCs?

Answer 34

intravitral imaging

Question 35

describe the experiment to see if S. aureus is replicating intracellularly

Answer 35

stained bacteria with blue dye
- if they replicate, will lose the blue and only see green

found that the bacteria were replicating within KCs

Question 36

is S. aureus actually drug-resistant?

Answer 36

no, the drug isn’t able to get to the bacteria bc it is intracellular so the bacteria was surviving

Question 37

what happens if a liposome is used to deliver the drug to S. aureus?

Answer 37

the drug can reach S. aureus within the cell

Question 38

what is a pathobiont?

Answer 38

symbiont that can promote pathology when specific genetic or environmental conditions in the host are altered

Question 39

why can ESKAPE pathogens not really be considered pathogens?

Answer 39

healthy people can have them without disease

Question 40

when do ESKAPE pathogens become pathogenic?

Answer 40

in immunosuppressed ppl