Micro Ii: Antibacterial Agents

Front 1

what are the main modes of action for antibacterial agents? (6)

Back 1

1. inhibit cell wall syn
2. disrupt PM
3. inhibit protein syn
4. inhibit nucleic acid syn
5. antimetabolites
6. target regulatory mol

Front 2

what is the BEST mode of action for antibacterial agents and why?

Back 2

inhibit cell wall syn; b/c not targeting a process that is used by host cells (less side effects, toxic)
"highly selective toxicity"

Front 3

why is targeting protein syn also a good mxn?

Back 3

bacteria use different ribosomes (30,50S) than eukaryotes (40,60S)
selective toxicity

Front 4

if a drug prevented cell wall syn would it be considered bactericidal or bacteriostatic?

Back 4

bacteriostatic b/c preventing formation of new microorganisms

Front 5

if a drug caused the break down of bacterial cell walls would it be considered bactericidal or bacteriostatic?

Back 5

bactericidal because it is causing bacterial cell death

Front 6

what are some drugs that inhibit cell wall syn? (4)

Back 6

1. penicillin (Penicillin binding protein)
2. cephalosporins
3. bacitracin
4. vancomycin

Front 7

drugs that inhibit protein syn? (4)

Back 7

1. chloramphenicol
2. erythromycin (macrolide)
3. tetracyclin (bacteriostatic)
4. streptomycin (aminoglycoside)
also, oxazolidones

Front 8

drugs that inhibit syn of metabolites (2)
what metabolite?

Back 8

1. sulfanilamide
2. trimethoprim
target folic acid syn

Front 9

drugs that inhibit nucleic acid replication, transcription (3)

Back 9

quinolones, rifampin and metronidazole

Front 10

drug that causes injury to PM

Back 10

polymyxin B
(also, lipopeptides and bacitracin)

Front 11

what are some methods by which bacteria become resistant to antibiotics? (5)

Back 11

1. alter target
2. active efflux
3. inactivate drug
4. decr uptake of drug
5. prod decoys

Front 12

why do bacteria become resistant to antibiotics? where are these genes found?

Back 12

bacteria have a high rate of replication and accumulate many mutations that can lead to drug resistance.
most antibiotic resistance genes are found on plsmids;
overuse of one antibiotic will result in proliferation of only bacteria that are resistant to that antibiotic

Front 13

how do bacteria decrease uptake of antibiotics?

Back 13

accumulate mutations in permeases and porins

Front 14

what are characteristics of antibacterial agents? (4)

Back 14

1.selective toxicity
2.cidal v. static
3.spectrum of activity
4. adverse host rxn (some)

Front 15

what is selective toxicity? what is an example?

Back 15

ablity to kill pathogen before/without killing host cell
most often in antibacterial b/c can target prokaryotic structures,fxns
ex: penicillin targeting PG in the cell wall

Front 16

how does vancomycin cause adverse host reaction?
what is important about this example?

Back 16

targets PG but also causes nephrotoxicity in pts with underlying renal disease
ADVERSE RXN MAY BE UNRELATED TO MXN OF ACTION OF THE DRUG!

Front 17

what is an ex of a bactericidal and a bacteriostatic agent?

Back 17

cidal: penicillin- decr # CFU and viable organisms
static: tetracycline-# org stays the same

Front 18

what is minimum inhibitory concentration?

Back 18

lowest concentration of a drug that stops GROWTH

Front 19

what is therapeutic index?

Back 19

ratio: drug toxic dose/MIC
imp for use and dosage

Front 20

why are antibiotics used in combination?

Back 20

to overcome bacterial resistance to the drugs

Front 21

what is an example of 2 antagonistic antibiotics

Back 21

penicillin and tetracyclin;
tetracyclin prevents growth and therefore prevents cell wall syn which is where penicillin would normally act (PBP, in log phase);
penicillin doesnt work on stationary cells

Front 22

what are inhibitors of cell wall syn (5)

Back 22

beta-lactams
glycopeptides
bacitracin
isoniazid (acid fast)
ethambutol (acid fast)

Front 23

what is the mxn of action of beta-lactams?

Back 23

inhibit cell wall syn
block PBP

Front 24

what is the MOA of glycopeptides?

Back 24

inhibit cell wall syn
block tetrapeptide linkage

Front 25

what is the mxn of action of bacitracin?

Back 25

inhibits cell wall syn
blocks recycling of transport proteins
(also interferes with cytoplasmic mbr integrity)

Front 26

what is the mxn of action of isoniazid?

Back 26

inhibits acid fast cell wall syn
blocks syn mycolic acid

Front 27

what is the mxn of action of ethambutol?

Back 27

block syn of arabinogalactan; acid fast cell wall inhibitor

Front 28

what is significant abt Augmentin?

Back 28

combination drug that fxns as beta-lactam and includes clavulanic acid which inhibits beta-lactamase

Front 29

what are the properties of cell wall inhibitors? (5)

Back 29

1. bind bacteria
2. penetrate outer mbr, periplasmic space of G-
3. interact with PBP on cytoplasmic mbr
4. upregulate autolysin-degrade muramic acid, PG of cell wall
5. bactericidal

Front 30

resistance to cell wall inhibitors (2)

Back 30

inactivate antibiotic (beta-lactamase)
alter target

Front 31

inhibitors of protein syn (4)

Back 31

aminoglycosides
tetracyclines
macrolides
oxazolidones

Front 32

mxn of aminoglycosides

Back 32

inhibit protein syn
interfere with f-met tRNA
cidal

Front 33

mxn tetracyclines

Back 33

inhibits protein syn
inhibit elongation (tRNA to acceptor site)
static

Front 34

mxn macrolides

Back 34

inhibit protein syn (CLEan TAG)
block translocation
(ex: Erythromycin)

Front 35

mxn oxazolidones

Back 35

inhibits protein syn
bind 50S; block ribosome assembly (initiation)

Front 36

properties of protein syn inhibitors (3)

Back 36

penetrate outer mbr G- (porins and permeases)
transported in via active transport system in cell mbr
bind ribosome, translation factors

Front 37

bacterial resistance to protein syn inhibitors (5)

Back 37

mutation of target
alter antibiotic
decr uptake (via porins, permeases)
active efflux
prod decoy

Front 38

inhibitors of NA syn(3)

Back 38

quinolones
rifampins, rifamycins
metronidazole

Front 39

mxn quinolones

Back 39

inhibit NA syn
G+: inhibit dna gyrase
G-: inhibit topo 4
cidal

Front 40

mxn rifampin/rifamycins

Back 40

inhibits NA syn
inhibit DNA dependent RNA polymerase (transcription)

Front 41

mxn metronidazole

Back 41

inhibits NA syn
binds DNA
(blocks H2 syn)
also works against anaerobic organisms and parasites

Front 42

charac of NA syn inhibitors

Back 42

penetrate outer mbr G-
transported in
bind NA, enzyme, TF

Front 43

resistance to NA syn inhibitors (2)

Back 43

change target (DNA gyrase, topo)
decr uptake (change cell wall permeability)

Front 44

antimetabolites (2)

Back 44

sulfonamides
trimethoprim
-used in combination to prevent resistance and treat broad range organisms

Front 45

mxn of sulfonamides

Back 45

antimetabolite
compete with PABA (substrate for folic acid syn)
used in conjuction with trimethoprim

Front 46

mxn of trimethoprim

Back 46

antimetabolite
inhibit dihydrofolate reductase (syn THF)

Front 47

resistance to antimetabolites (4)

Back 47

form permeablity barrier
alter target (enzyme)
ability to take up exogenous folic acid
intrinsic resistance for org that use exogenous thymidine (ex: enterococci)

Front 48

cytoplasmic mbr fxn inhibitors (3)

Back 48

polymyxins
lipopeptides
bacitracin

Front 49

mxn polymyxins

Back 49

inhibits PM fxn
increase cell permeablity

Front 50

mxn lipopeptides

Back 50

inhibits PM fxn
trigger rapid depolarization -> lose mbr potential, prevents protein, DNA, RNA syn

Front 51

mxn bacitracin

Back 51

damange mbr (also prevents cell wall syn)

Front 52

resistance to cytoplasmic mbr fxn inhibitors (3)

Back 52

mutation of target
alter antibiotic
decrease uptake (G- with modified phospholipid bilayer, porins)