NU 578 Unit 5 Exam (PDF) | Updated Exam
Questions | University of South Alabama
Question 1
A patient develops watery diarrhea 7 days after
completing a course of clindamycin. Which organism is
most likely responsible?
A. Escherichia coli
B. Clostridioides difficile
C. Salmonella
D. Campylobacter
Correct Answer: B
Rationale: Clindamycin is strongly associated with C.
difficile infection due to disruption of normal gut flora,
allowing toxin-producing C. difficile to overgrow. This
typically presents 5–10 days after antibiotic completion
with watery diarrhea, abdominal pain, and leukocytosis.
1
,Question 2
Which antibiotic is safe to use in a patient with a true
penicillin anaphylaxis?
A. Cephalexin
B. Ampicillin
C. Azithromycin
D. Amoxicillin-clavulanate
Correct Answer: C
Rationale: Macrolides like azithromycin have no cross-
reactivity with penicillins and are safe in patients with
true penicillin anaphylaxis. Cephalosporins carry a cross-
reactivity risk of approximately 1% and should be
avoided if possible.
Question 3
A patient on warfarin develops an INR of 5.0 after
starting a new antibiotic. Which antibiotic is most likely
responsible?
2
,A. Azithromycin
B. Cephalexin
C. Trimethoprim-sulfamethoxazole
D. Doxycycline
Correct Answer: C
Rationale: Trimethoprim-sulfamethoxazole (TMP-SMX)
inhibits CYP2C9 (warfarin metabolism) and displaces
warfarin from plasma proteins, significantly increasing
INR and bleeding risk. This interaction typically occurs
within 3–7 days of starting TMP-SMX.
Question 4
A 22-year-old female with uncomplicated urinary tract
infection has a sulfa allergy. Which antibiotic is most
appropriate?
A. Trimethoprim-sulfamethoxazole
B. Nitrofurantoin
3
, C. Ciprofloxacin
D. Ampicillin
Correct Answer: B
Rationale: Nitrofurantoin is first-line for uncomplicated
cystitis and has no cross-reactivity with sulfonamides.
TMP-SMX is contraindicated due to sulfa allergy.
Fluoroquinolones are reserved for complicated infections
due to resistance concerns.
Question 5
Which antibiotic requires dose adjustment in both renal
and hepatic impairment?
A. Ceftriaxone
B. Doxycycline
C. Rifampin
D. Tetracycline
Correct Answer: C
4
Questions | University of South Alabama
Question 1
A patient develops watery diarrhea 7 days after
completing a course of clindamycin. Which organism is
most likely responsible?
A. Escherichia coli
B. Clostridioides difficile
C. Salmonella
D. Campylobacter
Correct Answer: B
Rationale: Clindamycin is strongly associated with C.
difficile infection due to disruption of normal gut flora,
allowing toxin-producing C. difficile to overgrow. This
typically presents 5–10 days after antibiotic completion
with watery diarrhea, abdominal pain, and leukocytosis.
1
,Question 2
Which antibiotic is safe to use in a patient with a true
penicillin anaphylaxis?
A. Cephalexin
B. Ampicillin
C. Azithromycin
D. Amoxicillin-clavulanate
Correct Answer: C
Rationale: Macrolides like azithromycin have no cross-
reactivity with penicillins and are safe in patients with
true penicillin anaphylaxis. Cephalosporins carry a cross-
reactivity risk of approximately 1% and should be
avoided if possible.
Question 3
A patient on warfarin develops an INR of 5.0 after
starting a new antibiotic. Which antibiotic is most likely
responsible?
2
,A. Azithromycin
B. Cephalexin
C. Trimethoprim-sulfamethoxazole
D. Doxycycline
Correct Answer: C
Rationale: Trimethoprim-sulfamethoxazole (TMP-SMX)
inhibits CYP2C9 (warfarin metabolism) and displaces
warfarin from plasma proteins, significantly increasing
INR and bleeding risk. This interaction typically occurs
within 3–7 days of starting TMP-SMX.
Question 4
A 22-year-old female with uncomplicated urinary tract
infection has a sulfa allergy. Which antibiotic is most
appropriate?
A. Trimethoprim-sulfamethoxazole
B. Nitrofurantoin
3
, C. Ciprofloxacin
D. Ampicillin
Correct Answer: B
Rationale: Nitrofurantoin is first-line for uncomplicated
cystitis and has no cross-reactivity with sulfonamides.
TMP-SMX is contraindicated due to sulfa allergy.
Fluoroquinolones are reserved for complicated infections
due to resistance concerns.
Question 5
Which antibiotic requires dose adjustment in both renal
and hepatic impairment?
A. Ceftriaxone
B. Doxycycline
C. Rifampin
D. Tetracycline
Correct Answer: C
4
