Antimicrobial drugs and resistance

Question 1

antimicrobial drugs

Answer 1

• compounds that kill or control the growth of microorganisms in the host
• selective toxicity
• two broad categories
• synthetic and natural

Question 2

synthetic antimicrobial drugs

Answer 2

• growth factor analogs

- quinolones

Question 3

Growth factor analogs

Answer 3

• structurally similar to growth factors but do not function in the cell
• analogs similar to vitamins, amino acids, and other compounds
• sulfa drugs: discovered by Domagk
• inhibit growth of bacteria (ex. sulfanilamide) by inhibiting folic acid synthesis and thus nucleic acid synthesis

Question 4

quinolones

Answer 4

• inhibit DNA gyrase (ex. ciprofloxacin), prevent DNA supercoiling
• activate against broth gram-negative and gram-positive bacteria

Question 5

Natural antimicrobial drugs

Answer 5

-antibiotics
-produced by bacteria and fungi
-

Question 6

beta-lactam antibiotics (B-lactem)

Answer 6

-cell wall synthesis inhibitors
(ex penicillins and cephalosporins)
-comprise of over 50% of antibiotics used around the world

Question 7

penicillins

Answer 7

• discovered by alexander fleming
• target cell wall (peptidoglycan synthesis)
• transpeptidation
• effective against gram positive bacteria
• some synthetic forms active against gram negative bacteria

Question 8

B-lactem antibiotics 2 typos

Answer 8

• penicillin

- cephalosporins

Question 9

Cephalosporins

Answer 9

• fungus, cephalosporium sp.
• structurally different from penicillins
• similar mode of action to penicillins
• broader spectrum than penicillins
• resistant to B-lactamases
• commonly used to treat gonorrhea

Question 10

antibiotics from bacteria

Answer 10

• aminoglycosides
• marcolides
• tetracyclines
• novel antibiotics

Question 11

aminoglycosides

Answer 11

• amino sugars bonded by glycosidic linkage
• eg streptomycin, kanamycin, neomycin, gentamicin
• target 30S subunit of the ribosome
• useful against gram negative bacteria
• not as commonly used
• last resort antibiotics

Question 12

Macrolides

Answer 12

• lactone rings bonded to sugars
• eg. erythromycin (streptomyces erythreus)
• broad spectrum
• target 50S subunit of the ribosome
• partial inhibition of protein synthesis
• ->preferential translation of some proteins

Question 13

Tetracyclines

Answer 13

• produced by several species of streptomyces
• broad spectrum
• natural and semisynthetic
• inhibit 30S subunit of ribosome
• most widely used antibiotic along with penicillins
• veterinary and as growth promoters -> resistance

Question 14

novel antibiotics

Answer 14

• daptomycin

- platensimycin

Question 15

daptomycin

Answer 15

• produced by streptomyces
• cyclic lipopeptide -active against gram positives
• forms pores in CM ->depolarization

Question 16

platensimycin

Answer 16

• new class of antibiotics
• fatty acid biosynthesis inhibitor
• no host toxicity
• broad-spectrum including MRSA and VRE

Question 17

antimicrobial drug resistance

Answer 17

• ability of a microorganisms to resist the effects of an antimicrobial agent to which it is normally sensitive
• chromosomal Vs plasmid-encoded
• mechanisms of resistance

Question 18

resistance mechanisms

Answer 18

• resistance (R) plasmids
• widespread antibiotic usage in medicine, veterinary, and agriculture selects for resistance
• 80% of all antibiotic produced used for agricultural practices

Question 19

two types of resistance mechanisms

Answer 19

• methicillin-resistant staphylococcus aureus -MRSA

- Vanocomycin-resistant enterococci -VRE

Question 20

preventiving antimicrobial resistance

Answer 20

• prevention of infections
• rapid, conclusive diagnosis
• prevent use of antimicrobials
• prevention of transmission