M6 L5 Antibiotics

Question 1

what is an antimicrobial agent

Answer 1

substances that kill or inhibit growth of microorganisms

Question 2

classes of antimicrobial agents

Answer 2

• antibacterials
• antivirals
  -antifungals
• antiprotozoals
• anthelmintics (anthelmintics)

Question 3

what is a bacterial cell

Answer 3

• prokaryotes
• some with have capsule, cell wall, cell membrane, or plasma membrane
• not a proper nucleus, but has genetic tiny materials floating (plasmids)
• can b gram +’ve or -‘ve

Question 4

what does gram +’ve look under stain

Answer 4

purple, thick

Question 5

what colour does gram -‘ve look under stain

Answer 5

pink, thin

Question 6

what are cocci

Answer 6

circle bacteria

Question 7

what are bacilli

Answer 7

rod-like bacteria

Question 8

what are spirals

Answer 8

wavy/squiggly bacteria

Question 9

classes of antibiotics

Answer 9

• according to action
• according to spectrum
• according to effect

Question 10

what could antibiotics target (this is how we can differentiate them)

Answer 10

• cell wall
• cell membrane
• folic acid synthesis
• DNA
• Protein synthesis

Question 11

what antibiotics target the cell wall

Answer 11

-penicillin
-cephalosporins
-vancomycin

Question 13

what antibiotics target the folic acid synthesis

Answer 13

• sulfonamides
• trimethoprim
• co-trimoxasole

Question 14

what antibiotics target the DNA

Answer 14

• quinolones

Question 15

what antibiotics target the protein synthesis

Answer 15

-macrolides
- lincomasides
- tetracyclines
- aminolycosides

Question 16

narrow spectrum antibiotics

Answer 16

• gram +’ve cocci: penicillin G
• gram -‘ve bacilli: aminoglycosides

Question 17

broad spectrum antibiotics

Answer 17

• gram +’ve and -‘ve: tetracyclines

Question 18

what are bacteriostatic antibiotics

Answer 18

inhibit growth and reproduction of bacteria without killing them
ex: tetracyclines -sulfonamides

Question 19

what are bactericidal antibiotics

Answer 19

• kill the bacteria
• ex: penicillins - cephalosporins

Question 20

addition antibiotic combo

Answer 20

1+1=2

Question 21

synergism antibiotic combo

Answer 21

1+1=3
this is good u want this
- activity of combined agents is greater than sum of agents if given separately
ex:
- drug acting at sequential steps in metabolic pathway: sulfonamides + trimethoprim
- 1 drug prevents inactivation of 2nd: amoxicillin + clavulanate and imipenem + cilastatin

Question 22

antagonism antibiotic combo

Answer 22

1+1=0
bad

Question 23

what do bacteria do that causes antibiotics resistance

Answer 23

• altered receptors and enzymes
• altered rates of entry or removal
• enhanced inactivation
• synthesis of resistant pathways
• failure to metabolize drug

Question 24

penicillin structure

Answer 24

• derived from penicillium fungus
• core of 6-aminopenicillanic acid
• beta-lactam ring: active part, destroyed by beta-lactamase enzyme
• • side (R) group: determines type of penicillin

Question 25

mech of action of penicillin

Answer 25

- inhibit the formation of peptidoglycan cross-links in bacterial cell wall - spectrum: G +'ve +/- G-'ve can do both - bactericidal

Question 26

absorption/excretion/ROA for penicillin

Answer 26

absorption: variable w half life = 30-60 min excretion: thru kidney (90% tubular secretion), delayed by probenecid ROA: oral, IV, IM

Question 27

what is penicillin G (benzylpenicillin)

Answer 27

- mainly gram +'ve - acid labile - only parenteral - short acting - can b broken down by acid in stomach so cannot b taken orally - narrow spectrum

Question 28

what is penicillin V (phenoxymethylpenicillin)

Answer 28

similar to penicillin G (relative) but... can survive stomach acid! acid stable, can be taken orally

Question 29

what is benzathine benzylpenicillin

Answer 29

long acting penicillin (2-4 weeks) - IM injection

Question 30

what is beta-lactamase resistant penicillin examples

Answer 30

cloxacillin, dicloxacillin, methicillin

Question 31

broad spectrum penicillin examples

Answer 31

ampicillin and amoxicillin (does not resist staph aureus)

Question 32

adverse effects of penicillin

Answer 32

- hypersensitivity (anaphylaxis) - GI sympt: nausea, diarrhea - superinfection: candidiasis - drug resistance

Question 33

penicillin resistance

Answer 33

- destruction by beta-lactamase enzyme - synthesized by staphylococci - avoided by: clavulanic acid (potent-b-lactamase inhibitor, combined w some penicillins ex: amoxicillin), beta-lactamase resistant penicillins (ex: cloxacillin, dicloxacillin, methicillin

Question 34

cephalosporins

Answer 34

- beta-lactam antibiotic - derived from cephalosporium fungus - action/adverse effects/resistance}similar to penicillins

Question 35

1st generation of cephalosporins

Answer 35

- mainly gram +'ve ex: cefadroxil, cephalexin

Question 36

2nd generation cephalosporins

Answer 36

gram -'ve > gram +'ve ex: cefaclor, cefuroxime

Question 37

3rd generation cephalosporins

Answer 37

broad spectrum w more gram -'ve ex: cefotaxime, ceftriaxone

Question 38

4th generation cephalosporins

Answer 38

broad spectrum ex: cefepime, cefpirome

Question 39

5th generation cephalosporins

Answer 39

broad spectrum + MRSA ex: ceftaroline

Question 40

tetracyclines mech of action: effect: spectrum: Ca2+ chelation: oral absorption: administration: adverse effects: ex:

Answer 40

mech of action: reversible, inhibition of protein synthesis thru binding to 30S ribosomal subunit effect: bacteriostatic spectrum: broad Ca2+ chelation: ->insoluble complex -> inactivation oral absorption: variable administration: oral, topical adverse effects: delayed bone growth, tooth discoloration, photosensitivity ex: tetracycline, doxycycline

Question 41

aminoglycosides mech of action: effect: spectrum: Ca2+ chelation: oral absorption: administration: adverse effects: ex:

Answer 41

mech of action: irreversible, inhibition of protein synthesis thru binding to 30S ribosomal subunit effect: bactericidal spectrum: gram -'ve Ca2+ chelation: n/a oral absorption: poor administration: IV, IM, topical adverse effects: nephrotoxic, ototoxic ex: gentamicin, streptomycin

Question 42

sulfonamides

Answer 42

- 1st antimicrobial drug discovered - bacteriostatic - spectrum: gram +'ve and -'ve

Question 43

structure of sulfonamides

Answer 43

- derivatives of p-aminobenzoic acid (PABA) - diff "R" groups -> diff types

Question 44

sulfonamides mech of action

Answer 44

reversible competitive - decreased dihydropteroate synthetase enzyme - decreased conversion of PABA to dihydropteroate decrease folic acid synthesis

Question 45

trimethroprim mech of action

Answer 45

- decreased DHFR (dihydrofolic acid -> tetrahydrofolic acid)

Question 46

co-trimoxzole

Answer 46

sulfamethoxazole +trimethoprim useful for UTI's??

Question 47

sulfonamides pharmakinetics

Answer 47

- absorption: variable - carried by albumin - metabolized in liver - excreted thru kidney

Question 48

sulfonamides adverse effects

Answer 48

- hypersensitivity - urinary tract obstruction - hemolytic anemia

Question 49

route of admin for sulfonamides

Answer 49

oral, topical

Question 50

quinolones mechinism

Answer 50

- synthetic antibiotics - inhibit bacterial topoisomerase 2 (DNA gyrase) enzyme (required for transcription and DNA replication)

Question 51

quinolones spectrum, indications, administration

Answer 51

spectrum: broad indications: complicated UTI - serious G -'ve infections administration: oral ex: ciprofloxacin