Test 3: 38 antibiotics part 3

Question 1

— interfere with attachment of tRNA to 30s mRNA ribosome complex

Answer 1

tetracyclines

Question 2

— bind to 50S portion, prevents translocation- movement of ribosome along the mRNA

Answer 2

macrolide: erythromycin, azithromycin
chloramphenicol
lincosamide: lincomycin, clindamycin

binds to 50 S, A and P sites

Question 3

aminoglycosides are dose or concentration dependent

Answer 3

concentration (dose SID)

bactericidal

Question 4

aminoglycosides depend on — for active transport into bacteria via membrane pumps

Answer 4

oxygen

bactericidal (attack proteins synthesis- cause misreading)

Streptomycin A (prototype) Gentamycin A Kanamycin Amikacin Neomycin C (very toxic, external use only)

Question 5

mechanism of action for aminoglycosides

Answer 5

Bind to both subunits and prevent ribosome function.

Other drugs bind only one subunit

Binding to 30S subunit interferes with tRNA attachment and misshapes the codon interaction region. This causes misreading.

bactericidal

Question 6

cell membrane effect of aminoglycosides

Answer 6

cause holes in the bacteria cell membrane that lead to lysis

Question 7

mechanism of action of tetracyclines

Answer 7

Bind to 30S subunit and block tRNA attachment

bacteriostatic
broad spectrum

Tetracycline, Doxycycline, Chlortetracycline, Oxytetracycline, Methacycline, Minocycline

Question 8

— are some tetracyclines

Answer 8

Tetracycline Doxycycline Chlortetracycline Oxytetracycline Methacycline Minocycline

Bind to 30S subunit and block tRNA attachment
bacteriostatic
broad spectrum

Question 9

mechanism of action for puromycin

Answer 9

Binds to A-site in 50S subunit and causes premature termination

not used in clinic- research drug similar to aminoacyl- tRNA

Question 10

mechanism for macrolides

Answer 10

Bind to 50S subunit and prevent translocation along mRNA. Also blocks transpeptidase (Binds A and P site)

Bacteriostatic- lipid soluble- accumulates in tissues

Erythromycin (G+ > G-)
Azithromycin (G+ = G-)

Question 11

mechanism of lincosamides

Answer 11

Same mechanism as Macrolides
(50S, A and P site binding)

Bacteriostatic
Gram +
Can neutralize endotoxin so have been used for toxic shock

Clindamycin
Lincomycin

Question 12

— Can neutralize endotoxin so have been used for toxic shock

Answer 12

lincosamides

bacteriostatic Antibiotic that effects protein

Same mechanism as macrolides: Bind to 50S subunit and prevent translocation along mRNA. Also blocks transpeptidase (Binds A and P site)

lincomycin
clindamycin

Question 13

mechanism for chloramphenicol

Answer 13

Similar mechanism as Macrolides and Lincosamides (50S, P site, inhibits transpeptidation )

Bind to 50S subunit and prevent translocation along mRNA. Also blocks transpeptidase

Question 14

— most often used for dental disease (penetrates biofilm)

Answer 14

Clindamycin

type of lincosamide: bacteriostatic

Bind to 50S subunit and prevent translocation along mRNA. Also blocks transpeptidase (Binds A and P site)

Question 15

most antibiotics that are protein synthesis inhibitors are — except for —

Answer 15

bacteriostatic: tetracyclines, puromycin,macrolides, lincosamides, chloramphenicol

aminoglycosides: bacteriocidal

Question 16

Aminoglycosides works on which subunit of the ribosome

Answer 16

both 30S and 50S

different from other protein synthesis inhibitors that only work on one

Question 17

— is a protein synthesis inhibitor, can puncture the cell wall and is bactericidal

Answer 17

aminoglycoside

Question 18

Drugs affect the ribosome by binding and either inhibiting interactions (—) or changing the shape of the subunits (—)

Answer 18

transpeptidase

aminoglycosides

Question 19

what are two antibiotics that inhibit folic acid metabolism

Answer 19

Sulfonamides
Trimethoprim

mammals do NOT make their own folic acid

folic acid is used for portein and nucleic acid metabolism

Question 20

what are some sulfonamides

Answer 20

Family includes Sulfanilamide, Sulfadiazine, Sulfimethoxine, Sulfapyridine, Sulfizoxazole, Sulfazalazine and Sulfamethoxazole

inhibit folic acid metabolism

bacteriostatic- but when used in combo with trimethoprim becomes bacteriocidal
broad spectrum

Question 21

what happens when you use sulfonamides and trimethoprim

Answer 21

bacteriocidal

drugs inhibit folic acid synthesis in bacterial

they are bacteriostatic alone, but bacteriocidial when working together

Question 22

mechanism of action of sulfonamides and trimethoprim

Answer 22

• Sulfa drugs mimic pABA (block DHFS)
• Trimethoprim inhibits DHFR Folic Acid
• Bacterial DHFR > 6x104 more sensitive
  than mammalian DHFR.

inhibit folic acid metabolism in bacteria

Question 23

mechanism of action for polymyxin B

Answer 23

Polymyxins are cationic detergents that bind to LPS in Gram –ve Bacteria and disrupt the phospholipid bilayer - increases permeability and causes osmotic changes leading to bacterial death

inhibit cell membrane function

Question 24

— is a Pro-drug – activated in acid environment where it hydrolyses to produce formaldehyde

Answer 24

methenamine (mandelate/ hippurate)

bactericidal, broad spectrum

Question 25

isoniazid (INH)’

Answer 25

bactericidal antibiotic againist mycobacteria

Inhibits mycolic acid synthesis by inactivating Fatty Acid Synthase (FAS)-II

Pro-drug activated by a bacterial catalase named KatG

Question 26

— inhibits mycolic acid synthesis by inactivating Fatty Acid Synthase (FAS)-II

Answer 26

isoniazid (INH)’

prodrug
bactericidal
works againist mycobacteria

Question 27

— inhibits incorporation of mycolic acid into Arabinogalactan to make the cell wall

Answer 27

ethambutol (EMB)