Chapter 71-Intro to PCN Flashcards
What is the primary action of PCN?
a) bactericidal
b) bacteriostatic
Answer a)bactericidal
What is another name for penicillins?
a) beta-lactimase antibiotics
b) beta-lactim antibiotics
c) penicillinases
d) none of the above
Answer: b)beta-lactim antibiotics
What is primary MOA for penicillin?
a) 50s ribosome binding
b) inhibit transpeptidases
c) activation of autolysis
d) disrupt the cell wall
e) one or more of the above
Answer: e) one or more of the above
The primary MOA is disrupting the cell wall. This is achieved by inhibiting transpeptidases (enzymes that strength cell wall) and activating autolysis (breaks bonds in cell wall).
Where does PCN like to bind?
a) ribosomes
b) cell envelope
c) PBPs
d) none of these
Answer: c)PBPs
PCPs (penicillin-binding proteins) are the target of PCN. They are found on the membrane.
When can penicillin work?
a) when the cell is dying/weak
b) when the cell is growing
c) when the cell is dividing
d) all the time
e) one or more of the above
Answer: e) one or more of the above
PCN can only work during growth and division because that is the only time PBPs are expressed (penicillin binds to this on the bacteria)
How are human cells affected by penicillin?
a) all are destroyed
b) they are untouched
c) some are destroyed
d) some are damaged
Answer: b) they are untouched
Human cells do not have a cell wall for PCN to weaken/attach to. Therefore they are unaffected.
How does bacteria become resistant to PCN?
a) PCN is inactivated by enzymes
b) Proteins (PBP) are created which have high affinity for penicillin so the free circulating amount is higher
c) PBP are created which have a low affinity for penicillin
d) None of the above
e) One or more of the above
Answer: e)one or more of the above
Resistance can occur:
If penicillin can’t reach target PBP; if PCN is inactivated by bacterial enzymes; and if there is PBP produced which has a low affinity for penicillin (less binds)
Gram negative cell envelope has _____ layers and gram positive cell envelope has _____ layers.
Gram negative cell envelope has 3 layers and gram positive cell envelope has 2 layers.
Penicillin is more active against gram ____ bacteria.
Positive (it only has 2 layers in its’ envelope).
Beta-lactamases specific to penicillin are called:
penicillinases
What enzymes can cleave a beta-lactim ring?
a) beta-lactamases
b) penicillinases
c) carbapenemases
d) one or more
e) none
Answer: d) one or more
By cleaving the beta-lactim ring, beta-lactimases/penicillinases (specific to penicillin) the antibiotic is rendered inactive.
Gram _____ bacteria make a lot of penicillinases/beta-lactamases.
Gram positive. Gram negative bacteria make small amounts.
Which type of MRSA is more serious and harder to treat?
a) health care-associated MRSA
b) community-acquired MRSA
Answer: a
Note: MRSA used to be sensitive to penicillin but became resistant. Now it is resistant to methicillin
Penicillin G is more effective on most gram _____ bacteria.
Gram positive.
Which penicillin is referred to as “penicillin”?
a) Pen G
b) Pen V
c) Pen VK
d) none of the above
Answer: a) Pen G
Called “penicillin” as it was the first penicillin available
Penicillin is considered (broad/narrow) spectrum.
Answer: narrow
which makes it safer
Pen G is metabolized/eliminated primarily by:
a) liver
b) kidneys
c) both
Answer: b)kidneys
Eliminated primarily as unchanged drug
True or false, in penicillin allergy the dose does not matter?
True. The dose does not matter but prior exposure is necessary. This can occur through foods and other things.
True or false, penicillin is considered the least toxic of all antibiotics?
True.
True or false, if a patient has a mild PCN allergy, it is safe to give them cephalosporin.
True. Cross reaction sensitivity to cephalosporins in that situation is low at 1%
Anaphylaxis occurs more with ____ antibiotic than any other.
a) macrolide
b) tetracycline
c) clindamycin
d) penicillin
Answer: d)penicillin
Pen ___ is stable in stomach acid whereas Pen ___ is not.
Pen V is stable in stomach acid unlike Pen G
What benefits do penicillinase-resistant penicillins have?
Answer: they can resist penicillinase which would normally render penicillin inactive/useless
Also: they are highly resistant to inactivation by beta-lactamases
Penicillinase-Resistant Penicillins are (broad/narrow) spectrum whereas penicillins are (broad/narrow) spectrum.
Both are NARROW spectrum
Ampicillin and amoxicillin are considered (broad/narrow) spectrum penicillins.
Broad
Are broad spectrum penicillins inactivated by beta-lactamases?
Yes. Thus they will not work for S. aureus.
Which is an example of a broad-spectrum penicillin?
a) ampicillin
b) piperacillin
c) amoxicillin
d) pen V
e) pen VK
Answer: a & c
True or false, extended-Spectrum Penicillins are inactivated by beta-lactamases (penicillinases).
True.
Which is an example of an extended-spectrum penicillin?
a) ampicillin
b) piperacillin
c) amoxicillin
d) pen V
e) pen VK
Answer: b) piperacillin (it is the only one)
When you combine a penicillin with a beta-lactamase inhibitor, what can occur?
a) the penicillin degrades more quickly
b) the spectrum of penicillin extends
c) kidney toxicity can occur due to high levels of penicillin
d) beta-lactam cannot be expressed on the penicillin and it is not effective
Answer: b) extends the spectrum of the penicillin
Basically: prohibits the organism from creating the enzyme which breaks down penicillin
