USMLE Step 1 -- Pharmacology Answers
What is the prototype Beta-Lactam antibiotic? Which type is given IV and which type is
oral? When is IV the first line treatment of choice? - ANS-Penicillin
Penicillin G = I.V.
Penicillin V = Oral
Penicillin G is the treatment of choice for syphillis
What is the MOA of penicillin and other beta-lactam antibiotics? - ANS-(1) bind penicillin
binding proteins
(2) block transpeptidase cross-linking of peptidoglycan
(3)activate autolytic enzymes
What are the clinical uses for penicillins? [Generally and when is Pen. G first line?] -
ANS-Gram-Positive Organisms
First line for Syphilis
What comes to mind when discussing penicillin resistance? - ANS-Beta-lactamases
which cleave the beta-lactam ring
N.B. another name for beta-lactamase? Pencillinase
What are the three penicillinase-resistant penicillins? - ANS-Methicillin, Nafcillin,
Dicloxacillin
What is the major clinical use of the three penicillinase-resistant penicillins? What's a
nice mnemonic to help remember that? - ANS-"Use naf for staph."
Naficillin, dicloxacillin, and methacllin are all used to treat S. Aureus (except MRSA)
What are the two major aminopencillins and when do we use them? - ANS-Amoxicillin
and Ampicillin
[amOxicillin has greater Oral bioavailability than ampicillin]
Have a wider spectrum than pencillin, so HEELPSS kill gram positives and some gram
, negatives:
Haemophilus influenziae
E. Coli
Enterococci
Listeria Monocytogenes
Proteus Mirabilis
Salmonella
Shigella
What weird toxicity do we sometimes see with ampicillin? When? - ANS-Ampicillin rash,
mostly when someone has mono (EBV)
When would we use Ticarcillin, Carbenicillin, Piperacillin? [These 3 guys' class gives
them away...] - ANS-They're antipseudomonals, also called carboxypenicillins, so we
use them to treat pseudomonas spp. and other gram - rods
Mnemonic for our antipseudomonal antibiotics? Takes Care of Pseudomonas! -
ANS-Ticarcillin
Carbenicillin
Piperacillin
Beta-lactamase inhibitors are used in conjunction with: aminopenicillins,
antipseudomnals, etc. The Mnemonic CAST helps us remember that the major
beta-lactamase inhibitors are... - ANS-C lavulanic
A cid
S sulbactam
T azobactam
When do we use aminopenicillins (Amoxicillin, Ampicillin)? - ANS-Extended-spectrum
penicillin -- HELPSS kill enterococci
H. Flu
E. Coli
Listeria Monocytogenes
Proteus Mirabilis
Salmonella
What is the prototype Beta-Lactam antibiotic? Which type is given IV and which type is
oral? When is IV the first line treatment of choice? - ANS-Penicillin
Penicillin G = I.V.
Penicillin V = Oral
Penicillin G is the treatment of choice for syphillis
What is the MOA of penicillin and other beta-lactam antibiotics? - ANS-(1) bind penicillin
binding proteins
(2) block transpeptidase cross-linking of peptidoglycan
(3)activate autolytic enzymes
What are the clinical uses for penicillins? [Generally and when is Pen. G first line?] -
ANS-Gram-Positive Organisms
First line for Syphilis
What comes to mind when discussing penicillin resistance? - ANS-Beta-lactamases
which cleave the beta-lactam ring
N.B. another name for beta-lactamase? Pencillinase
What are the three penicillinase-resistant penicillins? - ANS-Methicillin, Nafcillin,
Dicloxacillin
What is the major clinical use of the three penicillinase-resistant penicillins? What's a
nice mnemonic to help remember that? - ANS-"Use naf for staph."
Naficillin, dicloxacillin, and methacllin are all used to treat S. Aureus (except MRSA)
What are the two major aminopencillins and when do we use them? - ANS-Amoxicillin
and Ampicillin
[amOxicillin has greater Oral bioavailability than ampicillin]
Have a wider spectrum than pencillin, so HEELPSS kill gram positives and some gram
, negatives:
Haemophilus influenziae
E. Coli
Enterococci
Listeria Monocytogenes
Proteus Mirabilis
Salmonella
Shigella
What weird toxicity do we sometimes see with ampicillin? When? - ANS-Ampicillin rash,
mostly when someone has mono (EBV)
When would we use Ticarcillin, Carbenicillin, Piperacillin? [These 3 guys' class gives
them away...] - ANS-They're antipseudomonals, also called carboxypenicillins, so we
use them to treat pseudomonas spp. and other gram - rods
Mnemonic for our antipseudomonal antibiotics? Takes Care of Pseudomonas! -
ANS-Ticarcillin
Carbenicillin
Piperacillin
Beta-lactamase inhibitors are used in conjunction with: aminopenicillins,
antipseudomnals, etc. The Mnemonic CAST helps us remember that the major
beta-lactamase inhibitors are... - ANS-C lavulanic
A cid
S sulbactam
T azobactam
When do we use aminopenicillins (Amoxicillin, Ampicillin)? - ANS-Extended-spectrum
penicillin -- HELPSS kill enterococci
H. Flu
E. Coli
Listeria Monocytogenes
Proteus Mirabilis
Salmonella
