Control of Microbial Population 2

Question 1

type of microbial drug that is effect on both protozoa and fungi

Answer 1

azoles

Question 2

why are sulfonamides so important

Answer 2

they can be used to treat both prokaryotes and eukaryotes

Question 3

what are aminoglycosides not effective against and why

Answer 3

not effective against anaerobes because of absent oxidative phosphorylation due to lack of oxygen

Question 4

what are glycopeptides not effective against and why

Answer 4

gram negative bacteria because they are too large and can’t penetrate through outer membrane

Question 5

what are nitroimidazoles not effective against and why

Answer 5

aerobes because they require activation by flavodoxin which is found only in anaerobes

Question 6

what are penicillins and cephalosporins not effective against and why

Answer 6

these things target particular structure which is the cell wall

mycoplasma because it lacks cell wall
mycobacteria because cell wall impenetrable

Question 7

what are some challenges with fungi infections?

Answer 7

harder to treat, usually chronic, longer tx time, recurrence is common, eukaryotes so similar to humans

Question 8

what was the first antifungal and are there many antifungals

Answer 8

azoles

not many because of challenge when it comes to treating fungi infections

Question 9

what are some sites of target for antifungal agents

Answer 9

nucleic acid synthesis (flucytosine)
cell membrane
direct membrane

Question 10

what do antifungal agents that target nucleic acids do

Answer 10

inhibits synthesis of DNA, RNA, and proteins

Question 11

what antifungal targets nucleic acid and what is its mechanism?

Answer 11

cytosine analogue 5-fluorocytosine (uses fungal enzyme) –> 5-fluorouracil –> 5-fluorouridyllic acid –> blocks synthesis of p nucleic acids that the fungi is going to need to replicate

Question 12

what is the difference between narrow and broad spectrum compounds

Answer 12

narrow - only treat one type of bacteria or fungi or virus

broad - treat several types of bacteria, fungi, or virus or even some cross over and treat both prokaryotes and eukaryotes

Question 13

name of antifungal that targets cell membrane

Answer 13

polyenes e.g. amphotericin B

specifically ergosterol

Question 14

what is the mechanism of polyenes (amphotericin B)

Answer 14

lipid loving compound that binds to ergosterol that create pores in the membrane causing leakage of ions out of the fungi –> cell lysis

Question 15

which antifungal compound is fungicidal

Answer 15

polyenes (amphotericin B) because it actually kills the fungi

Question 16

how does allylamines work

Answer 16

they are antifungals that interrupt the formation of ergosterol which is needed for cell membrane

it targets squalene epoxidase which turns squalene to lanesterol

Question 17

example of allylamines

Answer 17

terbinafine

Question 18

how do azoles work

Answer 18

they are antifungals that interrupt the formation of ergosterol which needed for cell membrane

it targets 14 alpha demethylase which turns lanesterol to ergosterol

Question 19

example of azoles

Answer 19

fluconazole (triazole)

Question 20

what are the two groups of azoles

Answer 20

imidazoles (two nitrogens)

triazoles (three nitrogens)

Question 21

effects of azoles on fungal growth

Answer 21

fungistatic and fungicidal depending on species and specific compound

Question 22

advantage of azoles

Answer 22

250 fold more effective against fungi sterols than against mammalian sterols

Question 23

what antifungal targets cell wall

Answer 23

echinocandins eg caspofungin

Question 24

mechanism of caspofungin

Answer 24

blocks (1,3) -beta-D-glucan synthetase –> prevents formation of chitin for cell wall

Question 25

what antibiotics target metabolism

Answer 25

sulfonamides (inhibitors of metabolism or nucleic acid synthesis)

Question 26

sulfonamides are derived from

Answer 26

prontosil

Question 27

mechanism of sulfonamides

Answer 27

blocks folic acid synthesis since bacteria synthesize their own antibiotics using PABA, sulfonamides are analogues of PABA so if taken up halts the production of folic acid

Question 28

what two drugs synergistically inhibit the synthesis of folic acid in fungi

Answer 28

sulfamethoxazole and trimethoprim | TMP-SMX/SMZ

Question 29

which antibiotics target protein synthesis in bacteria

Answer 29

tetracyclines, streptomycin, erythromycin, chloramphenicol

Question 30

what antibiotics target cell wall of bacteria

Answer 30

beta lactams

Question 31

what drugs fall under beta lactam and why? also how do these drugs work

Answer 31

penicillin, cephalosporins, monobactams, carbapenems -- all have beta lactam ring active only on growing cells

Question 32

what drugs inhibit the formation of cell wall of bacteria by attacking cytoplasm and cytoplasmic membrane respectively

Answer 32

cytoplasm - cycloserine | cytoplasmic membrane - bacitracin glycopeptides

Question 33

cross linking of NAM molecules in peptidoglycan is carried out by and this process is interfered with by what?

Answer 33

transpeptidases aka penicillin binding proteins beta lactams

Question 34

what happens to cell wall when beta lactams comes in and interferes with the cross linking of NAM molecules

Answer 34

they continue to grow (though they do not have the cement) but will eventually lyse since nothing is keeping it together

Question 35

mechanisms in which bacterias use to resist against antibiotics

Answer 35

altered uptake - decrease/block uptake of antibiotic or as soon as antibiotic gets into the bacteria is as soon as bacteria pumps it back out altered target - change in receptor affinity through mutation drug inactivation: beta lactamases, chloramphenicol, acetyltransferases

Question 36

most commonly used antifungal

Answer 36

azoles

Question 37

which drug is susceptible to all resistance mechanism of bacteria: altered target, altered uptake, drug inactivation

Answer 37

beta lactam

Question 38

which resistance mechanism by bacteria is mostly used against antibiotics

Answer 38

drug inactivation

Question 39

sources of resistance by bacteria

Answer 39

chromosomal mutation genes on transmissible plasmids genes on transposable elements (transposons)

Question 40

how does beta lactamase inactivate beta lactams

Answer 40

it cleaves the antibiotic at the beta lactam ring hence inactivating it

Question 41

most common beta lactamase

Answer 41

TEM beta lactamase

Question 42

confers resistance to all beta lactam anitibiotics and many other classes of antibiotics like aminoglycosides and fluoroquinolones

Answer 42

extended spectrum beta lactamases (ESBL)

Question 43

exception to ESBL

Answer 43

cephamycin (cefoxitin and cefotetan), carbapenems

Question 44

main producers of ESBL (extended spectrum beta lactamases) and KPC

Answer 44

enterobacteriacae particularly e. coli and klebsiella species

Question 45

KPC (klebsiella pneumoniae carbapenemases) are resistant to what

Answer 45

all beta lactams, fluoroquinolones, aminoglycosides associated with high therapeutic failure and high mortality rate

Question 46

Actions YOU as a healthcare practitioner can take to help limit the spread of resistance and selection of resistant strains

Answer 46

1. Wash your hands thoroughly between patient visits. 2. Do not give in to patients' demands for unneeded antibiotics. 3. When possible, prescribe antibiotics that target only a narrow range of bacteria. – Sensitivity testing 4. Isolate hospital patients with multi drug‐resistant infections. 5. Familiarize yourself with local data on antibiotic resistance.