NURS 5334 Antimicrobials: Questions With
Solutions (Correct & Verifi ed)
Section 1: General Principles & Pharmacodynamics (Questions 1-30)
1. A patient is prescribed a bactericidal antibiotic. The nurse understands that this
medication will:
a) Inhibit the growth of bacteria, allowing the immune system to clear the infection.
b) Destroy bacteria by targeting the cell wall, cell membrane, or DNA replication.
c) Slow the reproduction rate of bacteria without causing immediate cell death.
d) Alter the permeability of the bacterial ribosome to prevent protein synthesis.
Rationale: Bactericidal antibiotics kill bacteria directly. Bacteriostatic agents (Option A/C)
inhibit growth. Option D describes a mechanism (protein synthesis inhibition) which is
typically bacteriostatic, though some agents in this class can be bactericidal depending on
concentration.
2. A patient is receiving a combination of trimethoprim-sulfamethoxazole (TMP-SMX). The
nurse recognizes this combination is used primarily to:
a) Reduce the risk of nephrotoxicity compared to using either agent alone.
b) Achieve synergistic effects by blocking sequential steps in folic acid synthesis.
c) Widen the spectrum of coverage to include both gram-positive and anaerobic bacteria.
d) Decrease the half-life of the medications to allow for once-daily dosing.
Rationale: TMP-SMX exhibits synergy. Sulfamethoxazole inhibits dihydropteroate synthase,
and trimethoprim inhibits dihydrofolate reductase, sequentially blocking folic acid synthesis,
which is bactericidal for susceptible organisms.
3. Which laboratory value is most critical to monitor in a patient receiving an aminoglycoside
such as gentamicin?
a) Serum potassium
b) Hemoglobin A1c
c) Peak and trough levels
d) Prothrombin time
Rationale: Aminoglycosides have a narrow therapeutic index and cause dose-dependent
nephrotoxicity and ototoxicity. Monitoring peak (efficacy) and trough (toxicity) levels is
essential to prevent adverse effects.
,4. A patient develops a suprainfection (superinfection) while on broad-spectrum antibiotics.
What is the underlying pathophysiology of this complication?
a) Activation of dormant viral infections due to immune suppression.
b) Eradication of normal flora allowing opportunistic organisms to proliferate.
c) A type I hypersensitivity reaction to the antibiotic metabolite.
d) Antagonistic drug interaction between the antibiotic and antifungal agents.
Rationale: Broad-spectrum antibiotics disrupt the normal microbiome, eliminating protective
bacteria and allowing resistant or opportunistic organisms (e.g., *C. difficile*, *Candida*) to
overgrow.
5. Which statement best describes the concept of “post-antibiotic effect” (PAE)?
a) The duration of time that antibiotic concentrations remain above the MIC.
b) The allergic reaction that occurs after the completion of antibiotic therapy.
c) The persistent suppression of bacterial growth after antibiotic exposure has ended.
d) The synergistic effect achieved when combining a beta-lactam with a macrolide.
Rationale: PAE is the continued suppression of bacterial growth after the antibiotic has been
removed from the environment. It is particularly prominent with aminoglycosides and
fluoroquinolones.
6. A patient with a history of anaphylaxis to penicillin is ordered cefazolin. What is the
nurse’s priority action?
a) Administer the medication as ordered, as cross-reactivity is a myth.
b) Administer a test dose of cefazolin to confirm tolerance.
c) Hold the medication and contact the prescriber to discuss alternative therapy.
d) Pre-medicate with diphenhydramine and administer the dose slowly.
Rationale: While cross-reactivity between penicillins and cephalosporins is lower than
previously thought (approx. 1-2%), a history of anaphylaxis to penicillin is a relative
contraindication. The safest action is to hold the drug and verify the order with the
prescriber.
7. Which factor is most likely to contribute to antibiotic resistance?
a) Using narrow-spectrum antibiotics whenever possible.
b) Patients stopping antibiotics prematurely when symptoms resolve.
c) Administering antibiotics via the intravenous route for severe infections.
d) Decreased gastric pH due to concurrent proton pump inhibitor use.
Rationale: Incomplete courses of antibiotics (non-adherence) expose bacteria to sub-
therapeutic levels of the drug, selecting for resistant mutants. Narrow-spectrum use (A)
actually *reduces* resistance pressure.
,8. The nurse is administering vancomycin IV. The patient reports flushing, rash, and
hypotension 10 minutes into the infusion. The nurse suspects:
a) An anaphylactic reaction to the drug.
b) Red Man Syndrome caused by rapid infusion.
c) Extravasation of the medication into the tissues.
d) A transient hyperglycemic response.
Rationale: Red Man Syndrome (RMS) is a histamine-release reaction (not a true allergy)
associated with rapid IV infusion of vancomycin. It is managed by slowing the infusion rate
and sometimes pre-medicating with antihistamines.
9. A patient with renal impairment receives a dose of meropenem. The nurse understands
that this drug is eliminated primarily by:
a) Hepatic metabolism via the CYP450 system.
b) Renal excretion; therefore, dose adjustment is required.
c) Pulmonary expiration.
d) Fecal excretion via biliary elimination.
Rationale: Meropenem, like most beta-lactams (except ceftriaxone), is primarily renally
excreted. Dosage adjustments are necessary in renal impairment to prevent drug
accumulation and neurotoxicity.
10. Which antibiotic class is associated with the risk of tendonitis and tendon rupture?
a) Tetracyclines
b) Macrolides
c) Fluoroquinolones
d) Sulfonamides
Rationale: Fluoroquinolones (e.g., ciprofloxacin, levofloxacin) carry a black box warning for
tendonitis and tendon rupture, affecting the Achilles tendon most frequently. Risk increases
in patients over 60, those on corticosteroids, and organ transplant recipients.
11. The therapeutic efficacy of a time-dependent antibiotic (such as a beta-lactam) is best
predicted by:
a) The peak serum concentration (Cmax).
b) The ratio of peak concentration to MIC (Cmax/MIC).
c) The duration of time that the serum concentration remains above the MIC (T > MIC).
d) The total 24-hour area under the curve (AUC).
, Rationale: Beta-lactams exhibit time-dependent killing. Efficacy correlates with the time the
free drug concentration exceeds the MIC. Maintaining a high peak (A/B) is less relevant for
this class.
12. A patient is prescribed doxycycline. What instruction should the nurse provide to ensure
optimal absorption?
a) Take the medication with a glass of milk.
b) Take the medication with antacids to prevent gastrointestinal upset.
c) Take the medication with a full glass of water and avoid lying down for 30 minutes.
d) Take the medication on an empty stomach with orange juice.
Rationale: Doxycycline can cause esophageal irritation and ulceration. It should be taken
with adequate fluids and patients should remain upright. Dairy products and antacids (A/B)
chelate tetracyclines, reducing absorption.
13. Which antibiotic is associated with the development of a disulfiram-like reaction when
combined with alcohol?
a) Azithromycin
b) Metronidazole
c) Clindamycin
d) Nitrofurantoin
Rationale: Metronidazole inhibits aldehyde dehydrogenase, causing accumulation of
acetaldehyde when alcohol is ingested, leading to nausea, vomiting, flushing, and headache.
Cefotetan and some cephalosporins also cause this reaction.
14. A patient with a penicillin allergy is prescribed aztreonam. The nurse understands that
this drug is safe to administer because:
a) It is a carbapenem with a different ring structure.
b) It is a monobactam with minimal cross-reactivity to penicillins.
c) It requires a desensitization protocol prior to first dose.
d) It is a macrolide that works on the 50S ribosome.
Rationale: Aztreonam is a monobactam. Its side chain is distinct from penicillins and
cephalosporins, resulting in minimal immunologic cross-reactivity, making it generally safe
for patients with true penicillin allergies.
15. A nurse is administering IV clindamycin. The nurse knows this drug carries a black box
warning for:
Solutions (Correct & Verifi ed)
Section 1: General Principles & Pharmacodynamics (Questions 1-30)
1. A patient is prescribed a bactericidal antibiotic. The nurse understands that this
medication will:
a) Inhibit the growth of bacteria, allowing the immune system to clear the infection.
b) Destroy bacteria by targeting the cell wall, cell membrane, or DNA replication.
c) Slow the reproduction rate of bacteria without causing immediate cell death.
d) Alter the permeability of the bacterial ribosome to prevent protein synthesis.
Rationale: Bactericidal antibiotics kill bacteria directly. Bacteriostatic agents (Option A/C)
inhibit growth. Option D describes a mechanism (protein synthesis inhibition) which is
typically bacteriostatic, though some agents in this class can be bactericidal depending on
concentration.
2. A patient is receiving a combination of trimethoprim-sulfamethoxazole (TMP-SMX). The
nurse recognizes this combination is used primarily to:
a) Reduce the risk of nephrotoxicity compared to using either agent alone.
b) Achieve synergistic effects by blocking sequential steps in folic acid synthesis.
c) Widen the spectrum of coverage to include both gram-positive and anaerobic bacteria.
d) Decrease the half-life of the medications to allow for once-daily dosing.
Rationale: TMP-SMX exhibits synergy. Sulfamethoxazole inhibits dihydropteroate synthase,
and trimethoprim inhibits dihydrofolate reductase, sequentially blocking folic acid synthesis,
which is bactericidal for susceptible organisms.
3. Which laboratory value is most critical to monitor in a patient receiving an aminoglycoside
such as gentamicin?
a) Serum potassium
b) Hemoglobin A1c
c) Peak and trough levels
d) Prothrombin time
Rationale: Aminoglycosides have a narrow therapeutic index and cause dose-dependent
nephrotoxicity and ototoxicity. Monitoring peak (efficacy) and trough (toxicity) levels is
essential to prevent adverse effects.
,4. A patient develops a suprainfection (superinfection) while on broad-spectrum antibiotics.
What is the underlying pathophysiology of this complication?
a) Activation of dormant viral infections due to immune suppression.
b) Eradication of normal flora allowing opportunistic organisms to proliferate.
c) A type I hypersensitivity reaction to the antibiotic metabolite.
d) Antagonistic drug interaction between the antibiotic and antifungal agents.
Rationale: Broad-spectrum antibiotics disrupt the normal microbiome, eliminating protective
bacteria and allowing resistant or opportunistic organisms (e.g., *C. difficile*, *Candida*) to
overgrow.
5. Which statement best describes the concept of “post-antibiotic effect” (PAE)?
a) The duration of time that antibiotic concentrations remain above the MIC.
b) The allergic reaction that occurs after the completion of antibiotic therapy.
c) The persistent suppression of bacterial growth after antibiotic exposure has ended.
d) The synergistic effect achieved when combining a beta-lactam with a macrolide.
Rationale: PAE is the continued suppression of bacterial growth after the antibiotic has been
removed from the environment. It is particularly prominent with aminoglycosides and
fluoroquinolones.
6. A patient with a history of anaphylaxis to penicillin is ordered cefazolin. What is the
nurse’s priority action?
a) Administer the medication as ordered, as cross-reactivity is a myth.
b) Administer a test dose of cefazolin to confirm tolerance.
c) Hold the medication and contact the prescriber to discuss alternative therapy.
d) Pre-medicate with diphenhydramine and administer the dose slowly.
Rationale: While cross-reactivity between penicillins and cephalosporins is lower than
previously thought (approx. 1-2%), a history of anaphylaxis to penicillin is a relative
contraindication. The safest action is to hold the drug and verify the order with the
prescriber.
7. Which factor is most likely to contribute to antibiotic resistance?
a) Using narrow-spectrum antibiotics whenever possible.
b) Patients stopping antibiotics prematurely when symptoms resolve.
c) Administering antibiotics via the intravenous route for severe infections.
d) Decreased gastric pH due to concurrent proton pump inhibitor use.
Rationale: Incomplete courses of antibiotics (non-adherence) expose bacteria to sub-
therapeutic levels of the drug, selecting for resistant mutants. Narrow-spectrum use (A)
actually *reduces* resistance pressure.
,8. The nurse is administering vancomycin IV. The patient reports flushing, rash, and
hypotension 10 minutes into the infusion. The nurse suspects:
a) An anaphylactic reaction to the drug.
b) Red Man Syndrome caused by rapid infusion.
c) Extravasation of the medication into the tissues.
d) A transient hyperglycemic response.
Rationale: Red Man Syndrome (RMS) is a histamine-release reaction (not a true allergy)
associated with rapid IV infusion of vancomycin. It is managed by slowing the infusion rate
and sometimes pre-medicating with antihistamines.
9. A patient with renal impairment receives a dose of meropenem. The nurse understands
that this drug is eliminated primarily by:
a) Hepatic metabolism via the CYP450 system.
b) Renal excretion; therefore, dose adjustment is required.
c) Pulmonary expiration.
d) Fecal excretion via biliary elimination.
Rationale: Meropenem, like most beta-lactams (except ceftriaxone), is primarily renally
excreted. Dosage adjustments are necessary in renal impairment to prevent drug
accumulation and neurotoxicity.
10. Which antibiotic class is associated with the risk of tendonitis and tendon rupture?
a) Tetracyclines
b) Macrolides
c) Fluoroquinolones
d) Sulfonamides
Rationale: Fluoroquinolones (e.g., ciprofloxacin, levofloxacin) carry a black box warning for
tendonitis and tendon rupture, affecting the Achilles tendon most frequently. Risk increases
in patients over 60, those on corticosteroids, and organ transplant recipients.
11. The therapeutic efficacy of a time-dependent antibiotic (such as a beta-lactam) is best
predicted by:
a) The peak serum concentration (Cmax).
b) The ratio of peak concentration to MIC (Cmax/MIC).
c) The duration of time that the serum concentration remains above the MIC (T > MIC).
d) The total 24-hour area under the curve (AUC).
, Rationale: Beta-lactams exhibit time-dependent killing. Efficacy correlates with the time the
free drug concentration exceeds the MIC. Maintaining a high peak (A/B) is less relevant for
this class.
12. A patient is prescribed doxycycline. What instruction should the nurse provide to ensure
optimal absorption?
a) Take the medication with a glass of milk.
b) Take the medication with antacids to prevent gastrointestinal upset.
c) Take the medication with a full glass of water and avoid lying down for 30 minutes.
d) Take the medication on an empty stomach with orange juice.
Rationale: Doxycycline can cause esophageal irritation and ulceration. It should be taken
with adequate fluids and patients should remain upright. Dairy products and antacids (A/B)
chelate tetracyclines, reducing absorption.
13. Which antibiotic is associated with the development of a disulfiram-like reaction when
combined with alcohol?
a) Azithromycin
b) Metronidazole
c) Clindamycin
d) Nitrofurantoin
Rationale: Metronidazole inhibits aldehyde dehydrogenase, causing accumulation of
acetaldehyde when alcohol is ingested, leading to nausea, vomiting, flushing, and headache.
Cefotetan and some cephalosporins also cause this reaction.
14. A patient with a penicillin allergy is prescribed aztreonam. The nurse understands that
this drug is safe to administer because:
a) It is a carbapenem with a different ring structure.
b) It is a monobactam with minimal cross-reactivity to penicillins.
c) It requires a desensitization protocol prior to first dose.
d) It is a macrolide that works on the 50S ribosome.
Rationale: Aztreonam is a monobactam. Its side chain is distinct from penicillins and
cephalosporins, resulting in minimal immunologic cross-reactivity, making it generally safe
for patients with true penicillin allergies.
15. A nurse is administering IV clindamycin. The nurse knows this drug carries a black box
warning for:
