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Unit 2- Pharm > Inhibitors of Cell Wall Synthesis I > Flashcards

Inhibitors of Cell Wall Synthesis I Flashcards

1
Q

All inhibitors of cell wall synthesis are

A

bactericidal

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2
Q

Cell walls protect against

A

cell lysis

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3
Q

Five groups of inhibitors of cell wall synthesis?

A 
Cycloserine
Bactracin
Penicillins
Vancomycin
Fosfomycin
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4
Q

Gram positive bacteria has

A

thick peptidoglycan

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5
Q

Gram negative bacteria has

A

outer membrane + thin peptidoglycan layer

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6
Q

Major difference between bacterial and mammalian cells is presence of a

A

rigid cell wall external to the cell membrane

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7
Q

Cell wall protects bacterial cells rom

A

osmotic rupture - which would result from the fact that the cell is usually hyperosmolar to host environment

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8
Q

Peptidoglycan is composed of

A

a backbone of two alternating sugars, NAG and NAM

a chain of four AA that are linked to NAM

a peptide bridge that cross-links the tetrapeptide chain

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9
Q

Transglycosulation joins

A

NAM and NAG together

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10
Q

Transpeptidation joins

A

alanine with diaminopimetic acid

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11
Q

Peptidoglycan is the ____ of cells

A

armor

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12
Q

What makes the peptidoglycan really strong?

A

transpeptidation

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13
Q

What does transglycosulation and transpeptidation?

A

penicillin-binding proteins

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14
Q

Inhibition of any stage of the synthesis, export, or assembly or peptidoglycan lead to inhibition of bacterial cell growth and

A

cell death

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15
Q

Peptidoglycan is synonymous with

A

cell wall

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16
Q

How is peptidoglycan formed?

A
  1. addition of subunits (a sugar with its five attached AA)
  2. transport through cytoplasmic membrane to the cell surface
  3. subsequent cross-linking by cleavage of the terminal stem-peptide AA
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17
Q

Where are precursor units (NAM, NAG) assembled?

A

cytoplasm

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18
Q

What carries NAM and NAG across inner membrane?

A

lipid carrier

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19
Q

Where does peptidoglycan form?

A

outside of the inner membrane

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20
Q

Peptidoglycan synthesis:

Transglycosylation

Enzymatic action performed by:

A

joining of NAG and NAM

PBPs

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21
Q

Peptidoglycan synthesis:

Transpeptidation

Enzymatic action performed by:

A

cross links pentapeptides

PBPs

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22
Q

In peptidoglycan synthesis, NAG reduced to

A

NAM

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23
Q

In peptidoglycan synthesis, transport across

A

inner membrane

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24
Q

In peptidoglycan synthesis, amino acid mimicry

A

pentapeptide chain

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25
Transpeptidation is inhibited by
penicillins
26
If you give someone B-lactam antibiotics, what does not occur?
transpeptidation
27
If transpeptidation does not occur, what happens?
cell lyses
28
Inhibitors of cell wall synthesis are:
bactericidal to growing cells because they must be remodeling cells for it to work
29
Inhibitors of cell wall require what three things for activity and cell lysis.
Penicillin-binding proteins, active growth, and autolysins
30
Beta-lactam antibiotics prevent what?
cross-linking reaction called transpeptidation
31
If an infection has gone into latency, will inhibitors of cell wall synthesis work?
No.
32
Virtually all antibx that inhibit cell-wall synthesis are
bactericidal
33
cell death is due to
osmotic lysis
34
loss of cell wall integrity following treatment is due to the bacteria's own cell wall remodeling enzymes called _______ that cleave peptidoglycan bonds in the normal course of cell growth
autolysis
35
In the presence of agents that inhibit cell wall growth, ______ proceeds without normal cell-wall repair; weakness and eventual lysis occur.
autolysis
36
Protein synthesis inhibitors _____ action of the cell wall synthesis inhibitors.
prevent
37
If you put an inhibitor of cell growth with a static drug, will it be effective?
No - not effective b/c cell has stopped growing
38
If cell has stopped growing ______ antibiotics are useless.
beta-lactam
39
If a cell is being remodeled on the outside, what is happening on inside? If using beta-lactam antibiotics, what happens?
Making new units on inside Degradation continues Layer thickness does not change Making of new structures ceases
40
Are beta-lactam antibiotics useful with non-growing cells?
no.
41
8 criteria for properties of inhibitors of cell wall synthesis?
1. activity against gram (+) 2. spectrum (gram (-), anaerobic, coverage) 3. activity against pseudomonas aeruginosa 4. penicillinase resistance 5. acid resistance - oral absorption 6. CNS penetration 7. route of elimination 8. unique adverse effects
42
4 groups based on spectrums of penicillin
1. natural penicillin 2. penicillinase resistant 3. extended spectrum 4. antipseudomonal
43
4 natural penicillins
pen G pen V benzathine penicillin procaine penicillin G
44
4 penicillinase resistant penicillins
1. nafcillin 2. dicloxacillin 3. oxacillin (prostaphilin) 4. methicillin
45
2 extended spectrum penicillins
1. ampicillin | 2. amoxicillin
46
2 antipseudomonal penicillins
1. piperacillin | 2. ticarcillin
47
Penicillinase is a
method of bacterial resistance
48
Penicillinase AKA
beta-lactamase
49
What does penicillinase do?
enzyme that hydrolyzes beta-lactam ring so that it no longer bind to PBP (target)
50
How do some bacteria defend against antibiotics?
penicillinase
51
How does penicillin work?
it kills by interfering with the production of cell wall -- weakened cell wall rupture and cell dies
52
What type of penicillin has the highest antibacterial activity against certain G+ bacteria including G+ anaerobic bacteria
natural penicillins
53
Natural penicillins have ____ G- coverage.
some
54
Natural penicillins are readily activated by _______
beta lactamase
55
Natural penicillins are not effective against strains of
s. aureus
56
Natural penicillins have _____ antipseudomonal activity.
no
57
Natural penicillins are eliminated by
active transport in the kidney
58
Natural penicillins have ____ CNS penetration. Exception?
poor except in cases with inflammation -- with inflammation, natural penicillins have more CNS penetration
59
Penicillin G is adminstered how?
parentally. not well absorbed orally
60
Penicillin V is administered how?
relatively acid resistant - absorbed well orally
61
Penicillin G treats gram (+) or (-)
(+)
62
Penicillinase-Resistant Penicillins have what kind of activity against gram (+) and gram (-) bacteria?
lower activity against G+ bacteria and some G- coverage (more than natural penicillin)
63
Penicillin G treats these three major illnesses?
pneumococcal pneumonia syphilis gonorrhea (typically pen G is not first choice)
64
Some penicillinase-resistant penicillins are ____ stable and highy protein bound
acid
65
Penicillinase-resistant penicillins are
resistant to penicillinase
66
MSSA
methicillin sensitive staph aureus
67
more than ____% of S aureus isolates are resistant (MRSA)
20%
68
What kind of metabolism and excretion are associated with penicillinase-resistant penicillin?
hepatic metabolism renal excretion
69
What is a useful treatment for diabetics who have an infection with MSSA or MRSA and cannot take a lot of antiobiotics?
maggot therapy
70
MRSA is (mechanism of resistance)
penicillinase resistant
71
MRSA resistance is not associated with
production of beta-lactamase
72
MRSA produces _____ _____ which decreases affinity of beta-lactam antibiotics to PBPs
alternate PBP
73
_________ cannot be used to treat MRSA
beta-lactam
74
What is the exception for beta-lactams to treat MRSA
ceftaroline
75
beta-lactam induces cell lysis in normal cells in MRSA, what does not allow beta-lactam binding?
alteration in PBP
76
How does MRSA work?
changes the target of the drug so the drug cannot detect the altered PBP
77
Extended spectrum penicillins have what kind of coverage?
lower G+ coverage extended G- coverage (E. Coli, Salmonella, Shigella, H. Influenzae, Proteus) No antipseudomonal activity
78
resistance develops frequently or infrequently with extended spectrum penicillins
frequently
79
extended spectrum penicilins are susceptible to
beta-lactamase
80
extended spectrum penicillins are/are not acid resistant
are
81
extended spectrum penicillins are excreted how
urinary excretion
82
what is extended spectrum penicillins a drug of choice for
lysteria infections
83
What are penicillinase-resistant penicillins a drug of choice for?
penicillinase-producing s. aureus (MSSA)

Unit 2- Pharm (9 decks)

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