First Aid USMLE Step 1: Pharmacology (Complete)
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Quiz: Penicillin G (IV and IM)
Penicillin M (oral)
Ans: *MOA:*
*β-lactam*: a structural analog of D-ala-D-ala (a normal component of cell walls) which
binds and inactivates bacterial transpeptidases (penicillin-binding protein, PBPs) to block
peptidoglycan cross linking
*Clinical use:*
Bactericidal for Gram-⊕ cocci/rods, Gram-⊖ cocci (Neisseria), and spirochetes
Mostly used for Gram-⊕ organisms (S. pneumoniae, S. pyogenes, Actinomyces). Also used
for Gram-⊖ cocci (mainly N. meningitidis) and spirochetes (namely T. pallidum).
Bactericidal for Gram-⊕ cocci, Gram-⊕ rods, Gram-⊖ cocci, and spirochetes. Penicillinase
sensitive.
*Toxicity:*
Hypersensitivity reactions (type II), hemolytic anemia
*MOR:*
Penicilinase (a type of β-lactamase) in bacteria cleaves
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, Quiz: Oxacillin
Nafcillin
Dicloxacillin
Ans: Penicillinase-resistant penicillins
*MOA:*
Same as penicillin.
*Narrow spectrum*; penicillinase resistant because bulky R group blocks access of β-
lactamase to β-lactam ring.
*Clinical use:*
Bactericidal, narrow spectrum: *S. aureus* (except MRSA; resistant due to altered
penicillin-binding protein target site).
*Toxicity:*
Hypersensitivity reactions (type II), interstitial nephritis
"Use *naf* (*naf*cillin) for staph." Nafcillin has penetration to CNS
Quiz: Aminopenicillins:
Ampicillin
Amoxicillin
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, Ans: Penicillinase-sensitive penicillins
*MOA:*
Same as penicillin.
Wider spectrum with better activity against Gram-⊖ bugs; penicillinase sensitive.
Administer with clavulanic acid to protect against destruction by β-lactamase.
*Clinical use:*
Bactericidal for Gram-⊕ cocci/rods, Gram-⊖ cocci, spirochetes; Extended-spectrum
penicillin: *H.* influenzae, *H.* pylori, *E.* coli, *L*isteria monocytogenes, *P*roteus
mirabilis, *S*almonella, *S*higella, enterococci. *HHELPSS*
*Toxicity:*
Hypersensitivity reactions (type II), ampicillin rash (often with EBV infection- reaction-not
an allergy), pseudomembranous colitis
*MOR:*
β-lactamase activity
Quiz: Ticarcillin
Piperacillin
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, Ans: Ureidopenicillins: "Antipseudomonals"
*MOA:*
Same as penicillin. Extended spectrum.
*Clinical use:*
*Pseudomonas spp.* and Gram-⊖ rods
Hospital-acquired pneumonias (Klebsiella, H. influenzae, Enterobacter)
Susceptible to penicillinase; use with β-lactamase inhibitors.
*Toxicity:*
Hypersensitivity reactions (type II)
Quiz: Clavulanic Acid
Sulbactam
Tazobactam
o
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Questions and Correct Detailed Answers (Verified
Answers) ||Already Graded A+||Newest Version
Quiz: Penicillin G (IV and IM)
Penicillin M (oral)
Ans: *MOA:*
*β-lactam*: a structural analog of D-ala-D-ala (a normal component of cell walls) which
binds and inactivates bacterial transpeptidases (penicillin-binding protein, PBPs) to block
peptidoglycan cross linking
*Clinical use:*
Bactericidal for Gram-⊕ cocci/rods, Gram-⊖ cocci (Neisseria), and spirochetes
Mostly used for Gram-⊕ organisms (S. pneumoniae, S. pyogenes, Actinomyces). Also used
for Gram-⊖ cocci (mainly N. meningitidis) and spirochetes (namely T. pallidum).
Bactericidal for Gram-⊕ cocci, Gram-⊕ rods, Gram-⊖ cocci, and spirochetes. Penicillinase
sensitive.
*Toxicity:*
Hypersensitivity reactions (type II), hemolytic anemia
*MOR:*
Penicilinase (a type of β-lactamase) in bacteria cleaves
o
o
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, Quiz: Oxacillin
Nafcillin
Dicloxacillin
Ans: Penicillinase-resistant penicillins
*MOA:*
Same as penicillin.
*Narrow spectrum*; penicillinase resistant because bulky R group blocks access of β-
lactamase to β-lactam ring.
*Clinical use:*
Bactericidal, narrow spectrum: *S. aureus* (except MRSA; resistant due to altered
penicillin-binding protein target site).
*Toxicity:*
Hypersensitivity reactions (type II), interstitial nephritis
"Use *naf* (*naf*cillin) for staph." Nafcillin has penetration to CNS
Quiz: Aminopenicillins:
Ampicillin
Amoxicillin
o
o
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, Ans: Penicillinase-sensitive penicillins
*MOA:*
Same as penicillin.
Wider spectrum with better activity against Gram-⊖ bugs; penicillinase sensitive.
Administer with clavulanic acid to protect against destruction by β-lactamase.
*Clinical use:*
Bactericidal for Gram-⊕ cocci/rods, Gram-⊖ cocci, spirochetes; Extended-spectrum
penicillin: *H.* influenzae, *H.* pylori, *E.* coli, *L*isteria monocytogenes, *P*roteus
mirabilis, *S*almonella, *S*higella, enterococci. *HHELPSS*
*Toxicity:*
Hypersensitivity reactions (type II), ampicillin rash (often with EBV infection- reaction-not
an allergy), pseudomembranous colitis
*MOR:*
β-lactamase activity
Quiz: Ticarcillin
Piperacillin
o
o
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, Ans: Ureidopenicillins: "Antipseudomonals"
*MOA:*
Same as penicillin. Extended spectrum.
*Clinical use:*
*Pseudomonas spp.* and Gram-⊖ rods
Hospital-acquired pneumonias (Klebsiella, H. influenzae, Enterobacter)
Susceptible to penicillinase; use with β-lactamase inhibitors.
*Toxicity:*
Hypersensitivity reactions (type II)
Quiz: Clavulanic Acid
Sulbactam
Tazobactam
o
o
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