Penicillins (Lec 12)

Question 1

Bacteria are hypo-, hyper- or isoosmolar to host environment?

Answer 1

hyperosmolar

rigid cell wall keeps them from lysing

Question 2

G+ and G- cell walls made of?

Answer 2

peptidoglycan

Question 3

Peptidoglycan made of?

Answer 3

backbone of alternating sugars:
N-acetylglucosamine (NAG)
N-acetylmuramic acid (NAM)

4 AA chain linked to NAM

Peptide bridge cross-linking

Question 4

3 stages of peptidoglycan assembly

Answer 4

1) sugar subunits assembled in cyto
2) sugars transported thru membrane to cell surface
3) cross-linking AA peptides

Question 5

Drugs that inhibit cell wall synth (ICWS) are (U) what kind?

Cause death how?

Answer 5

bactericidal

osmotic lysis

Question 6

Autolysins are?

Answer 6

remodeling enzymes in bacterial cell wall,

cleave peptidoglycan bonds for normal cell growth

Question 7

Bactericides effect autolysins how?

Answer 7

allow autolysins to cleave bonds without subsequent wall repair,
wall weakens and allows lysis

Question 8

ICWS drugs are primarily what kind?

Answer 8

β-lactams

Question 9

4 specific β-lactams

Answer 9

1) penicillins
2) cephalosporins
3) monobactams
4) carbapenems

Question 10

4 non-β-lactam ICWS

Answer 10

1) vancomycin
2) phosphomycin
3) bacitracin
4) cycloserine

Question 11

What drug is the Natural Penicillin prototype?

Answer 11

Penicillin G

Question 12

What drug is the Penicillinase-Resistant Penicillin prototype?

Answer 12

Nafcillin

Question 13

What drug is the Extended Spectrum Penicillin prototype?

Answer 13

Ampicillin

Amoxicillin

Question 14

What drug is the Antipseudomonal Penicillin prototype?

Answer 14

Piperacillin

Question 15

Natural Penicillins provide highest activity against what type of bacteria?

Answer 15

G+, some G-

Question 16

Natural Penicillins inactivated by?

Answer 16

β-lactamase (penicillinase)

Question 17

Penicillinase-Resistant Penicillins is drug of choice against?

Answer 17

penicillinase-producing s. arueus (MSSA)

• > 20% of s. aureus types are resistant (MRSA)

Question 18

MRSA is resistant to penicillins how?

Answer 18

Produces Penicillin-Binding Protein 2a (not β-lactamase) ->
β-lactam antibiotics don’t bind to PBP2a ->
can’t cause cell lysis

Question 19

Extended Spectrum Penicillins provided extended coverage against?

Answer 19

G-, G+

Question 20

Extended Spectrum Penicillins not active against what G- bacteria?

Answer 20

pseudomonas

Question 21

Extended Spectrum Penicillins is drug of choice against?

Answer 21

listeria

h. plyori (+bismuth + metronidazole0

Question 22

Ampicillin rashes are not caused by?

Answer 22

hypersensitivity (allergy)

Question 23

Antipseudomonal Penicillins active against?

Answer 23

G-: extended spectrum

Question 24

Antipseudomonal Penicillins DOC for?

Answer 24

pseudomonas aeruginosa (+ aminoglycoside)

Question 25

Antipseudomonal Penicillins should be used in combination with what to prevent resistance?

Answer 25

aminoglycosides

Question 26

Addition of β-lactamase Inhibitors to Extended Spectrum Penicillins and Antipseudomonal Penicillins does what?

Answer 26

extends their spectrums to include many bacteria previously resistance because of β-lactamase prodxn

Question 27

β-lactamase combination drugs are NOT active against?

Answer 27

MRSA

methicillin resistant penicillinase producing staphylococci

Question 28

Bacterial Resistance to Penicillins:

5 methods

Answer 28

1) β-lactamase inactivates drug
2) G- decreased permeability to drug
3) Alternate PBPs that prevent drug binding
4) Drug inability to activate autolytic enzymes
5) Bacteria lack peptidoglycan wall

Question 29

Pencillin toxicity caused by? (4)

Answer 29

1) allergy
2) electrolyte imbalance
3) GI disturbances
4) superinfections

Question 30

PCN is DOC?

Answer 30

all G+ strep

enterococcus