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Flashcards in antibiotics med chem Deck (97)
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1

mutualistic relationship

both organisms benefit

2

opportunistic relationship

under normal conditions the microbe does not cause disease, but can if certain conditions are met

3

features of gram positive bacteria

-Outer peptidoglycan layer
-stains purple

4

features of gram negative bacteria

-out lipopolysaccharide layer
-porins provide channels through LPS
-stains pink

5

antibiotics that are from manmade sources

sulfa drugs
fluoroquinolones
linezolid

6

bacteriocidal

kills bacteria
(technically all antibiotics are bacteriocidal at high doses)

7

bacteriostatic

inhibits growth of bacteria

8

sugar with the peptide attached for cross linking in peptidoglycan

NAM

9

amino acids needed to form cross-link

-D-Ala D-Ala on NAM
-pentaglycine chains linking the NAMs

10

steps of forming peptidoglycan cross-link

in cytoplasm
1. synthesize NAM
2. attach NAG and prenyl
3. add peptide side chain
4. flipping into periplasm

in periplasm
5. form crosslink

11

enzyme that makes crosslinks

transpeptidase

12

what facilitates transport of NAG and NAM into periplasm

bactoprenol

13

how does transpeptidation take place?

1. penicillin binding protein has an active Ser that attacks the non-terminal D-Ala forming an ester bond
2. Ester bond can be attacked by an amine in the pentaglycine chain via transpeptidation, forming a cross link

14

beta-lactam MoA

mimic D-Ala D-Ala to form a bond with PBP and prevent it from being used to make cross links, thus opening the cells wall

15

definition of a lactam ring

an intramolecular ring with an amine and a carboxylic acid linked with varying amounts of carbons (alpha=1, beta=2, and so on)

16

what part of beta-lactams mimics the D-Ala D-Ala peptide

the acidic withdrawing group on the lactam ring

17

Problems with beta lactams

-degraded by water and stomach acid due to its instability
-resistance via beta-lactamase, penicillinase, and other mechanisms

18

beta-lactamase function

hydrolysis of penicillins

19

location of beta-lactamase in gram positive bacteria

outside the peptidoglycan

20

location of beta-lactamase in gram negative bacteria

periplasmic space, between LPS and cytoplasmic membraine

21

general SAR of penicillins

-required S in ring
-ring system
-no substitution on ring
-"west end" has amide linkage
-aromatic or cyclic function in "west end" R group
-dimethyl on east end

22

penicillin G features

-early penicillin
-very Gm+ (no staph)
-little Gm-
-unstable when given orally

23

penicillin V features

-early penicillin
-very Gm+ (no staph)
-little Gm-
-given orally b/c of ether electron withdrawing group

24

early penicillins

Pen G
Pen V

25

methicillin features

-ortho groups prevent beta-lactamase attack
-ok GM+
-little GM-
-given IV

26

nafcillin features

-ortho groups prevent beta-lactamase attack
-ok GM+ (staph)
-little GM-
-given IV

27

oxacillins feature

-ortho groups prevent beta-lactamase attack
-ok GM+ (staph)
-little GM-
-given oral

28

penicillinase-resistant penicillins

-methicillin
-nafcillin
-oxacillins (oxacillin, cloxacillin, dicloxacillin)

29

ampicillin/amoxicillin features

-amino group good for passing through porins
-good Gm-
-good Gm+
-good substrate for beta-lactamase
-ineffective against pseudomonas
-given orally

30

broad-spectrum penicillins

ampicillin
amoxicillin