Antibiotic Overview

Question 1

Drugs that affect cell wall synthesis (3)

Answer 1

vancomycin
cephalosporins
carbapeneins

Question 2

What is different in the cell was of bacteria that permits targeted therapy?

Answer 2

Well for one they HAVE a cell wall

Also - proteoglycan composition (fungi don’t have this, neither do mycoplasma, so keep that in mind)

Question 3

Drugs that affect bacterial cell membrane

Answer 3

Polymyxins

daptomycin

Question 4

What composition of cell wall allows eukaryote vs fungi distinction?

Answer 4

Ergosterol is found in fungi while cholesterol is found in humans

Question 5

Drugs that inhibit 50S ribosomal subunit in bacteria

Answer 5

Erythromycin (macrolides)

Clindamycin

Question 6

Drugs that inhibit 30S ribosomal subunit

Answer 6

tetracycline
streptomycin
tobramycin (aminoglycoside)
amikacin

Question 7

Drugs that inhibit tRNA in bacteria

Answer 7

mupirocin

linezolid

Question 8

Drugs that inhibit DNA gyrase

Answer 8

quinolones

Question 9

Drugs that inhibit RNA-directed RNA polymerase

Answer 9

rifampin

Question 10

Drugs that inhibit DNA replication in bacteria

Answer 10

metronidazole

nitrofuratonin

Question 11

Drugs that inhibit folic acid metabolism/synthesis

Answer 11

trimethoprim

sulfonamide

Question 12

Why is folic acid inhibition drugs used in bacteria and not eukaryotes?

Answer 12

Bacteria MUST synthesize folate while eukaryotes like us can just obtain it through diet

Question 13

What are the three modes of drug resistance?

Answer 13

1. ) Natural (intrinsic) resistance
2. ) Escape
3. ) Acquired Resistance (subtypes: chromosomal resistance and plasmid mediated resistance)

Question 14

Resistance via altered binding site - penicillin binding proteins

Answer 14

Occurs in MRSA, pneumoniae, enterococci (gram + cocci)

Resistance to beta lactam antibiotics (penicillins, cephalosporins, carbapenems)

Question 15

Resistance via altered binding site - DNA gyrase

Answer 15

Occurs in S. aureus, Pseudomonas

Resistance to flouroquinolones

Question 16

Resistance via altered binding site - peptidoglycan sidechain

Answer 16

Occurs in enterococci (VRC) and staph (VRSA)

Resistance to vancomycin

Question 17

Resistance via enzymatic degradation - beta-lactamase

Answer 17

Occurs in s. auerus, p. aeruginosa, enterococci

Resistance to beta lactams (penicillins, cephalosporins, carbapenems)

Question 18

Resistance via altered binding site - 50S ribosome methylation

Answer 18

Occurs in strep, staph and enterococci (gram + cocci)

Resistance to erythromycin, clindamycin

Question 19

Resistance via enzymatic degradation - acetyl-phospho-adenylyl

Answer 19

Occurs in enterococci

Resistance to aminoglycosides

Question 20

Resistance via enzymatic degradation - acetyltransferases

Answer 20

Occurs in staph, strep, neisserria

Resistance to chloromphenicol.

Question 21

Resistance via bypass pathway - overproduction of PABA/thymidine nucleotides

Answer 21

Occurs in strep

Resistance to sulfanomides

Question 22

Resistance via decreased entry

Answer 22

p. auruginosa - to beta lactams
pseudomonas - to flouroquinolones
e. coli + pseudomonas - to aminoglycosides

Question 23

Resistance due to efflux pump

Answer 23

Occurs in step, staph and entero
To tetracyclines, macrolides

Occurs ALSO in pseudomonas
To flouroquinolones

Question 24

What are the features of “bactericidal” drugs

Answer 24

Inhibit cell wall synthesis
Disrupt cell membrane fxn
Interference w/ DNA fxn or synthesis

Preferred for severe infections, quick and irreversible, compensate for pts w/ impaired host defense and required for treatment of infections located in immune sanctuaries (such as the CNS/endocarditis)

Question 25

What are the features of "bacteriostatic" drugs

Answer 25

Inhibition of protein synthesis | Inhibition of intermediary metabolic pathways

Question 26

What is the IMPORTANT exception of protein synthesis inhibition drugs that ISNT bacteriostatic?

Answer 26

aminoglycosides are BACTERIOCIDAL lol

Question 27

What are some examples of beneficial selective distribution?

Answer 27

Clindamysin in bone (osteomyelitis) Macrolides in pulm. cells (URIs->pneumonia) Tetracyclines in gingival crevicular fluid and sebum (periodontis + acne) Nitrofurantoin is quick urine excretion (UTIs!)

Question 28

What are some examples of TOXIC selective distribution?

Answer 28

Aminoglycosides in inner ear and renal brush boder (ototoxicity + nephrotoxicity) Tetracyclines bind Ca2+ in developing bone and teeth (abnormal bone growth and tooth discoloration!)

Question 29

What is renal dosing

Answer 29

Select dose or frequency dependent of pt's renal fxn. Monitored by serum creatinine (SCr) and estimation of creatinine clearence (CrCl)

Question 30

Concentration-dependent killing

Answer 30

antibiotics that kill faster in doses that result in high initial Cp levels SUCH AS! flouroquinolones, aminoglycosides!

Question 31

Time dependent killing

Answer 31

kill best when Cp is above MIC for longer durations SUCH AS! beta lactams, vancomycin, macrolides

Question 32

Post-antibiotic effect

Answer 32

antibiotics that continue action ater Cp < MIC. Less frequent dosing. SUCH AS! AGs, FQs, macrolides, beta lactrams (gram + > gram - )