NCLEX-RN Pharmacology Infection Drugs Exam
| 20 Antibiotics, Antifungals & Antivirals
Practice Questions with Rationales
Question 1
Clinical Scenario
A 64-year-old male is admitted with a severe complicated intra-
abdominal infection. The provider prescribes intravenous
vancomycin and piperacillin/tazobactam. The client has a
history of chronic kidney disease (Stage 3). The morning
laboratory results reveal a blood urea nitrogen (BUN) of $32
\text{ mg/dL}$ and a serum creatinine of $2.1 \text{ mg/dL}$
(elevated from a baseline of $1.4 \text{ mg/dL}$ two days ago).
Question Stem
Which action should the nurse take first before administering
the next scheduled dose of vancomycin?
A. Administer the piperacillin/tazobactam through a separate IV
line.
B. Hold the vancomycin dose and notify the healthcare provider.
C. Draw a vancomycin peak level 30 minutes after completing
the infusion.
,D. Check the client’s deep tendon reflexes and urinary output.
Correct Answer
Correct Answer: B. Hold the vancomycin dose and notify the
healthcare provider.
Detailed Rationale
Vancomycin is a glycopeptide antibiotic that carries a significant
risk of nephrotoxicity, which is compounded when administered
concurrently with piperacillin/tazobactam. This client's serum
creatinine has jumped significantly from a baseline of $1.4
\text{ mg/dL}$ to $2.1 \text{ mg/dL}$, indicating acute kidney
injury (AKI). Administering another dose of vancomycin in the
face of worsening renal function can lead to drug accumulation,
severe toxicity, and permanent kidney damage. The nurse's
priority action must be to withhold the medication to prevent
further harm and contact the provider for dose adjustment or a
change in therapy, as well as to request a trough level.
Option A is incorrect because while separating IV lines is
important for incompatible drugs, it does not address the acute
kidney injury. Option C is incorrect because vancomycin
monitoring relies on trough levels (drawn immediately before
the next dose) rather than peak levels to determine safety and
efficacy. Option D is an assessment that should be done, but
holding a known nephrotoxic drug in a patient with a
,documented, acute laboratory spike in creatinine is the
definitive, high-priority safety intervention.
Learning Objectives
After completing this question, the learner should be able to:
• Recognize the clinical signs of antibiotic-induced
nephrotoxicity based on laboratory values.
• Prioritize nursing actions when an adverse drug event is
suspected.
• Identify the correct timing and utility of vancomycin trough
level monitoring.
Medication Safety Focus
Monitoring / Black Box Warning (Nephrotoxicity)
Question 2
Clinical Scenario
A 28-year-old female client with a history of mechanical heart
valve replacement is diagnosed with a severe urinary tract
infection and is prescribed ciprofloxacin. She takes warfarin
daily to prevent valve thrombosis.
Question Stem
What is the primary reason the nurse must closely monitor this
client's international normalized ratio (INR)?
, A. Ciprofloxacin accelerates the hepatic metabolism of warfarin,
increasing clotting risk.
B. Fluoroquinolones decrease vitamin K-producing gut flora,
enhancing the anticoagulant effect of warfarin.
C. Warfarin impairs the gastrointestinal absorption of oral
fluoroquinolones.
D. Ciprofloxacin increases renal clearance of warfarin, requiring
higher warfarin doses.
Correct Answer
Correct Answer: B. Fluoroquinolones decrease vitamin K-
producing gut flora, enhancing the anticoagulant effect of
warfarin.
Detailed Rationale
Fluoroquinolones, such as ciprofloxacin, are broad-spectrum
antibiotics that eliminate a significant portion of the normal
bacterial flora in the gut. Because these intestinal bacteria are
responsible for synthesizing vitamin K (which the liver uses to
produce clotting factors), a reduction in flora results in less
available vitamin K. When a client takes warfarin—a vitamin K
antagonist—alongside ciprofloxacin, the anticoagulant effect of
warfarin is significantly amplified, dramatically increasing the
risk of major bleeding.
| 20 Antibiotics, Antifungals & Antivirals
Practice Questions with Rationales
Question 1
Clinical Scenario
A 64-year-old male is admitted with a severe complicated intra-
abdominal infection. The provider prescribes intravenous
vancomycin and piperacillin/tazobactam. The client has a
history of chronic kidney disease (Stage 3). The morning
laboratory results reveal a blood urea nitrogen (BUN) of $32
\text{ mg/dL}$ and a serum creatinine of $2.1 \text{ mg/dL}$
(elevated from a baseline of $1.4 \text{ mg/dL}$ two days ago).
Question Stem
Which action should the nurse take first before administering
the next scheduled dose of vancomycin?
A. Administer the piperacillin/tazobactam through a separate IV
line.
B. Hold the vancomycin dose and notify the healthcare provider.
C. Draw a vancomycin peak level 30 minutes after completing
the infusion.
,D. Check the client’s deep tendon reflexes and urinary output.
Correct Answer
Correct Answer: B. Hold the vancomycin dose and notify the
healthcare provider.
Detailed Rationale
Vancomycin is a glycopeptide antibiotic that carries a significant
risk of nephrotoxicity, which is compounded when administered
concurrently with piperacillin/tazobactam. This client's serum
creatinine has jumped significantly from a baseline of $1.4
\text{ mg/dL}$ to $2.1 \text{ mg/dL}$, indicating acute kidney
injury (AKI). Administering another dose of vancomycin in the
face of worsening renal function can lead to drug accumulation,
severe toxicity, and permanent kidney damage. The nurse's
priority action must be to withhold the medication to prevent
further harm and contact the provider for dose adjustment or a
change in therapy, as well as to request a trough level.
Option A is incorrect because while separating IV lines is
important for incompatible drugs, it does not address the acute
kidney injury. Option C is incorrect because vancomycin
monitoring relies on trough levels (drawn immediately before
the next dose) rather than peak levels to determine safety and
efficacy. Option D is an assessment that should be done, but
holding a known nephrotoxic drug in a patient with a
,documented, acute laboratory spike in creatinine is the
definitive, high-priority safety intervention.
Learning Objectives
After completing this question, the learner should be able to:
• Recognize the clinical signs of antibiotic-induced
nephrotoxicity based on laboratory values.
• Prioritize nursing actions when an adverse drug event is
suspected.
• Identify the correct timing and utility of vancomycin trough
level monitoring.
Medication Safety Focus
Monitoring / Black Box Warning (Nephrotoxicity)
Question 2
Clinical Scenario
A 28-year-old female client with a history of mechanical heart
valve replacement is diagnosed with a severe urinary tract
infection and is prescribed ciprofloxacin. She takes warfarin
daily to prevent valve thrombosis.
Question Stem
What is the primary reason the nurse must closely monitor this
client's international normalized ratio (INR)?
, A. Ciprofloxacin accelerates the hepatic metabolism of warfarin,
increasing clotting risk.
B. Fluoroquinolones decrease vitamin K-producing gut flora,
enhancing the anticoagulant effect of warfarin.
C. Warfarin impairs the gastrointestinal absorption of oral
fluoroquinolones.
D. Ciprofloxacin increases renal clearance of warfarin, requiring
higher warfarin doses.
Correct Answer
Correct Answer: B. Fluoroquinolones decrease vitamin K-
producing gut flora, enhancing the anticoagulant effect of
warfarin.
Detailed Rationale
Fluoroquinolones, such as ciprofloxacin, are broad-spectrum
antibiotics that eliminate a significant portion of the normal
bacterial flora in the gut. Because these intestinal bacteria are
responsible for synthesizing vitamin K (which the liver uses to
produce clotting factors), a reduction in flora results in less
available vitamin K. When a client takes warfarin—a vitamin K
antagonist—alongside ciprofloxacin, the anticoagulant effect of
warfarin is significantly amplified, dramatically increasing the
risk of major bleeding.
