NURS 572 PRACTICE EXAM WEEK 2 ANTIBIOTICS
400 QUESTIONS & CORRECT ANSWERS LATEST
2026/2027
What is the active structure in beta-lactam antibiotics? - ANSWER-The beta-
lactam ring, which confers antibacterial effects
What is the primary mechanism of action for beta-lactams? - ANSWER-They bind
to bacterial enzymes transpeptidase, carboxypeptidase, and endopeptidase, thereby
inhibiting cell wall synthesis and leading to eventual cell lysis.
Why are human cells unaffected by beta-lactams? - ANSWER-Human cells lack a
cell wall and do not have peptidoglycan.
When is beta-lactam efficacy maximized? - ANSWER-When the drug
concentration exceeds the minimum inhibitory concentration (MIC) for 40% to
60% of the dosing interval.
How are penicillins characterized? - ANSWER-By 6-aminopenicillanic acid joined
to the beta-lactam ring
What are the four subclasses of penicillins? - ANSWER-Natural penicillins,
aminopenicillins, antistaphylococcal penicillins, and antipseudomonal or extended-
spectrum penicillins.
How many natural penicillins are commercially available? - ANSWER-Four:
Penicillin V, procaine penicillin, benzathine penicillin, and penicillin G.
,What types of organisms are natural penicillins active against? - ANSWER-
Aerobic, gram-positive organisms, including Streptococcus species, group A
betahemolytic Streptococcus (GABHS), some Enterococcus strains, and some non-
penicillinase-producing staphylococci.
Why are natural penicillins rarely used to treat infections caused by
Staphylococcus aureus? - ANSWER-Because most Staphylococcus aureus species
excrete penicillinase, which hydrolyzes the beta-lactam ring of natural penicillins,
rendering them ineffective.
What is the significance of the pneumococcal conjugate vaccine (PCV-7)? -
ANSWER-It has contributed to the decrease in invasive infections caused by
Streptococcus pneumoniae and Penicillin-resistant Streptococcus pneumoniae
What are the indications for using penicillin G? - ANSWER-It is reliable for
treating Listeria monocytogenes but not effective against Neisseria gonorrhoeae or
Staphylococcus species due to rising resistance.
Which two aminopenicillins are available? - ANSWER-Ampicillin and
amoxicillin.
What types of organisms are aminopenicillins active against? - ANSWER-They
have reliable activity against gram-positive organisms and greater activity against
gram-negative bacteria.
Why are amoxicillin and ampicillin often combined with beta-lactamase inhibitors,
clavulanic acid and sulbactam, respectively? - ANSWER-They are beta-lactamase
inhibitors, which prevent the destruction of beta-lactam antibiotics by inhibiting
beta-lactamase, thereby enhancing gram-negative and anaerobic activity.
,What organisms do ampicillin/sulbactam and amoxicillin/clavulanate have
excellent activity against/ - ANSWER-Methicillin-susceptible Staphylococcus
aureus (MSSA), Streptococcus and Enterococcus species, Moraxella catarrhalis,
Haemophilus influenzae, Neisseria meningitidis, Salmonella, some Shigella
species, Pasteurella multocida, Actinomyces, Clostridium, Peptostreptococcus, and
Bacteroides fragilis
What are antistaphylococcal penicillins? - ANSWER-They are modified penicillins
that are stable in the presence of penicillinase produced by staphylococci.
However, modification led to the elimination of activity against Enterococcus
species, Listeria, and gram-negative bacteria.
What are examples of antistaphylococca penicillins? - ANSWER-Nafcillin (only
available IV), oxacillin (only available IV), and dicloxacillin (only available PO)
What species are antistaphylococcal penicillins active against? - ANSWER-
Streptococcus species, MSSA, and Peptostreptococcus
What is the mecA gene? - ANSWER-A bacterial gene encoding an altered
penicillin binding protein (PBP2a) that has low affinity for all beta-lactams,
causing high-level resistance to methicillin, penicillin, and other beta-lactam
antibiotics. It is most well-known as the genetic marker that defines Methicillin-
resistant Staphylococcus aureus (MRSA)
What is the only antibiotic used to treat MRSA? - ANSWER-IV cephalosporin
ceftaroline
What are antipseudomonal penicillins? - ANSWER-- Comprised of a single
combination product: piperacillin and a betalactamase inhibitor, tazobactam.
- Only available for IV administration in the United States.
, Which bacteria does piperacillin/tazobactam have enhanced activity against? -
ANSWER-Pseudomonas aeruginosa, Enterobacter, Morganella, Escherichia coli,
Klebsiella species, and Proteus mirabilis
What is the most common mechanism of resistance to penicillins? - ANSWER-
Beta-lactamase production, an enzyme that inactivates beta-lactams, including
penicillins
What is the role of beta-lactamase inhibitors like tazobactam? - ANSWER-They
irreversibly inactivate beta-lactamase enzymes and protect antibiotics from
inactivation
What are the differences between penicillinases and extended-spectrum beta-
lactamases (ESBLs)? - ANSWER-- Penicillinases are beta-lactamases produced by
S. aureus and Haemophilus species that cahn be inactivated by beta-lactamase
inhibitors
- Extended-spectrum beta-lactamases (ESBLs) are produced by E. coli, Klebsiella
species, and Enterobacter species, and are not generally inhibited by beta-
lactamase inhibitors
Why are oral antibiotics limited to mild-moderate infections? - ANSWER-Because
higher than recommended doses cause GI distress, diarrhea, and serum
concentrations do not rise proportionately with increased doses.
Which penicillins are well-absorbed orally? - ANSWER-Penicillin V and
dicloxacillin
Why is amoxicillin preferred for oral administration over ampicillin? - ANSWER-
Because amoxicillin is more completely absorbed with a bioavailability of 80%
400 QUESTIONS & CORRECT ANSWERS LATEST
2026/2027
What is the active structure in beta-lactam antibiotics? - ANSWER-The beta-
lactam ring, which confers antibacterial effects
What is the primary mechanism of action for beta-lactams? - ANSWER-They bind
to bacterial enzymes transpeptidase, carboxypeptidase, and endopeptidase, thereby
inhibiting cell wall synthesis and leading to eventual cell lysis.
Why are human cells unaffected by beta-lactams? - ANSWER-Human cells lack a
cell wall and do not have peptidoglycan.
When is beta-lactam efficacy maximized? - ANSWER-When the drug
concentration exceeds the minimum inhibitory concentration (MIC) for 40% to
60% of the dosing interval.
How are penicillins characterized? - ANSWER-By 6-aminopenicillanic acid joined
to the beta-lactam ring
What are the four subclasses of penicillins? - ANSWER-Natural penicillins,
aminopenicillins, antistaphylococcal penicillins, and antipseudomonal or extended-
spectrum penicillins.
How many natural penicillins are commercially available? - ANSWER-Four:
Penicillin V, procaine penicillin, benzathine penicillin, and penicillin G.
,What types of organisms are natural penicillins active against? - ANSWER-
Aerobic, gram-positive organisms, including Streptococcus species, group A
betahemolytic Streptococcus (GABHS), some Enterococcus strains, and some non-
penicillinase-producing staphylococci.
Why are natural penicillins rarely used to treat infections caused by
Staphylococcus aureus? - ANSWER-Because most Staphylococcus aureus species
excrete penicillinase, which hydrolyzes the beta-lactam ring of natural penicillins,
rendering them ineffective.
What is the significance of the pneumococcal conjugate vaccine (PCV-7)? -
ANSWER-It has contributed to the decrease in invasive infections caused by
Streptococcus pneumoniae and Penicillin-resistant Streptococcus pneumoniae
What are the indications for using penicillin G? - ANSWER-It is reliable for
treating Listeria monocytogenes but not effective against Neisseria gonorrhoeae or
Staphylococcus species due to rising resistance.
Which two aminopenicillins are available? - ANSWER-Ampicillin and
amoxicillin.
What types of organisms are aminopenicillins active against? - ANSWER-They
have reliable activity against gram-positive organisms and greater activity against
gram-negative bacteria.
Why are amoxicillin and ampicillin often combined with beta-lactamase inhibitors,
clavulanic acid and sulbactam, respectively? - ANSWER-They are beta-lactamase
inhibitors, which prevent the destruction of beta-lactam antibiotics by inhibiting
beta-lactamase, thereby enhancing gram-negative and anaerobic activity.
,What organisms do ampicillin/sulbactam and amoxicillin/clavulanate have
excellent activity against/ - ANSWER-Methicillin-susceptible Staphylococcus
aureus (MSSA), Streptococcus and Enterococcus species, Moraxella catarrhalis,
Haemophilus influenzae, Neisseria meningitidis, Salmonella, some Shigella
species, Pasteurella multocida, Actinomyces, Clostridium, Peptostreptococcus, and
Bacteroides fragilis
What are antistaphylococcal penicillins? - ANSWER-They are modified penicillins
that are stable in the presence of penicillinase produced by staphylococci.
However, modification led to the elimination of activity against Enterococcus
species, Listeria, and gram-negative bacteria.
What are examples of antistaphylococca penicillins? - ANSWER-Nafcillin (only
available IV), oxacillin (only available IV), and dicloxacillin (only available PO)
What species are antistaphylococcal penicillins active against? - ANSWER-
Streptococcus species, MSSA, and Peptostreptococcus
What is the mecA gene? - ANSWER-A bacterial gene encoding an altered
penicillin binding protein (PBP2a) that has low affinity for all beta-lactams,
causing high-level resistance to methicillin, penicillin, and other beta-lactam
antibiotics. It is most well-known as the genetic marker that defines Methicillin-
resistant Staphylococcus aureus (MRSA)
What is the only antibiotic used to treat MRSA? - ANSWER-IV cephalosporin
ceftaroline
What are antipseudomonal penicillins? - ANSWER-- Comprised of a single
combination product: piperacillin and a betalactamase inhibitor, tazobactam.
- Only available for IV administration in the United States.
, Which bacteria does piperacillin/tazobactam have enhanced activity against? -
ANSWER-Pseudomonas aeruginosa, Enterobacter, Morganella, Escherichia coli,
Klebsiella species, and Proteus mirabilis
What is the most common mechanism of resistance to penicillins? - ANSWER-
Beta-lactamase production, an enzyme that inactivates beta-lactams, including
penicillins
What is the role of beta-lactamase inhibitors like tazobactam? - ANSWER-They
irreversibly inactivate beta-lactamase enzymes and protect antibiotics from
inactivation
What are the differences between penicillinases and extended-spectrum beta-
lactamases (ESBLs)? - ANSWER-- Penicillinases are beta-lactamases produced by
S. aureus and Haemophilus species that cahn be inactivated by beta-lactamase
inhibitors
- Extended-spectrum beta-lactamases (ESBLs) are produced by E. coli, Klebsiella
species, and Enterobacter species, and are not generally inhibited by beta-
lactamase inhibitors
Why are oral antibiotics limited to mild-moderate infections? - ANSWER-Because
higher than recommended doses cause GI distress, diarrhea, and serum
concentrations do not rise proportionately with increased doses.
Which penicillins are well-absorbed orally? - ANSWER-Penicillin V and
dicloxacillin
Why is amoxicillin preferred for oral administration over ampicillin? - ANSWER-
Because amoxicillin is more completely absorbed with a bioavailability of 80%
