Lecture 4: Antibiotics

Question 1

what is anti-biotic resistance?

Answer 1

ability of organism to grow in presence of something that should inhibit growth

Question 2

what are colicins / holins?

Answer 2

small proteins that poke holes in membrane of other cells to damage integrity

Question 3

how do colicins enter a host cell?

Answer 3

bind to membrane proteins

Question 4

what are the 3 mechanisms of action by colicins?

Answer 4

1. intracellular nuclease on DNA, rRNA, tRNA
2. formation of depolarizing de-energizing ion-conducting channels in cytoplasmic membrane that damage it
3. stop cell wall synthesis (no peptidoglycan?)

Question 5

nature has created antibiotic naturally overtime by

Answer 5

natural selection

Question 6

what are some ways in which natural antibiotics are modified to be therapeutic?

Answer 6

1. hydrophilic / soluble
2. less toxic
3. smaller
4. more stable

Question 7

what makes a good target of inhibition for an antibiotic?

Answer 7

1. something unique

2. something essential

Question 8

examples of good targets of inhibition

Answer 8

peptidoglycan, cell wall, protein translation, ribosomes, dna replication, lipids

Question 9

methicilins

Answer 9

amoxicilin, ampicilin, carbenicilin; naturally quite toxic

Question 10

examples of protein synthesis inhibitor antibiotics

Answer 10

chloramphenicol, erythromycin, kanamycin, tetracycline, streptomycin

Question 11

examples of DNA inhibitor antibiotics

Answer 11

ciprofloacin and other fluroquinolones

Question 12

DNA gyrase inhibitors prevent ____ which makes an easy target for

Answer 12

unwinding of DNA to be replicated; innate immune system

Question 13

examples of small peptide antibiotics

Answer 13

bacitracin, vancomycin

Question 14

small peptide antibiotics typically come in what form?

Answer 14

topical creams that bind to membranes of cells

Question 15

bacitracin targets

Answer 15

gram + cells

Question 16

glycopeptide (Bacitracin)

Answer 16

glucose group that can bind to CW and stop CW replication

Question 17

how are methicilins modified for therapeutic use?

Answer 17

B-lactam antibodies are modified

Question 18

what is the function of B-lactams?

Answer 18

block CW biosynthesis by inhibiting transpeptide linkage to peptidoglycan

Question 19

what are B-lactamases?

Answer 19

enzymes secreted by bacteria to cleave B-lactam rings to make the drug ineffective

Question 20

what is added to antibiotics to act as a B-lactamase inhibitor?

Answer 20

clavulinic acid

Question 21

what is a biofilm?

Answer 21

capsules from slimy, sticky film thats impermeable to external agents

Question 22

what is especially bad about a biofilm?

Answer 22

protects bacteria while allowing them to be exposed to sub-lethal conditions that make them stronger

Question 23

survival of bacteria with a biofilm depends on

Answer 23

size, integrity, shape

Question 24

after treatment with colistin, a slide of bacteria will appear__ at the surface and ___ on the inside under a confocal scope

Answer 24

surface green = alive

red = dead bacteria

Question 25

why are the inner parts of a bacteria killed by an antiobiotic?

Answer 25

there are aqueous channels in biofilms that antibiotics go through and killing inner, but not surface

Question 26

what are efflux pumps?

Answer 26

multi-component protein channels in the bacterial membrane that pump out toxins

Question 27

TF : efflux pumps existed before antibiotics

Answer 27

true

Question 28

why did efflux pumps exist before antibiotics?

Answer 28

heavy metals, chemicals

Question 29

efflux pumps span from ___ to ___

Answer 29

inner to outer membrane

Question 30

parts of efflex pumps are embedded in

Answer 30

inner, outer membranes and periplasm

Question 31

what is an example of natural anti-biotic?

Answer 31

streptomyces bacteria

Question 32

how do streptomyces make anti-biotics?

Answer 32

secrete molecules that inhibit growth of other bacteria

Question 33

2 examples of streptomyces bacteria

Answer 33

spreptomycin and kanamycin

Question 34

would flagella be a good target for anti-biotics?

Answer 34

not necessarily, because swimming isnt everything

Question 35

what is a common site of biofilms?

Answer 35

catheters and other medical plastics

Question 36

what is added to catheters to prevent biofilm formation?

Answer 36

antimicrobials