Lippincott Chapter 39. Protein Synthesis Inhibitors

Question 1

39.1 Which of the following antibiotic combinations is inap-
propriate based on antagonism at the same site of action?
A. Clindamycin and erythromycin.
B. Doxycycline and amoxicillin.
C. Tigecycline and azithromycin.
D. Ciprofloxacin and amoxicillin

Answer 1

Correct answer = A. Clindamycin and erythromycin share
the same site of action on the 50S ribosomal subunit and
may result in antagonism, rendering both drugs ineffective.
They also share cross-resistance.

Question 2

39.2 Children younger than 8 years of age should not receive
tetracyclines because these agents:
A. Cause rupture of tendons.
B. Deposit in tissues undergoing calcification.
C. Do not cross into the cerebrospinal fluid.
D. Can cause aplastic anemia.

Answer 2

Correct answer = B. Tetracyclines are contraindicated in this
age group because they are deposited in tissues under-
going calcification, such as teeth and bone, and can stunt
growth. Ciprofloxacin can interfere in cartilage formation
and cause rupture of tendons and is also contraindicated in
children, but it is a fluoroquinolone. Tetracyclines can cross
into the cerebrospinal fluid. They do not cause aplastic ane-
mia, a property usually associated with chloramphenicol.

Question 3

39.3 A 30-year-old pregnant female has cellulitis caused by
MRSA. Which of the following antibiotics would be the
most appropriate option for outpatient therapy?
A. Doxycycline.
B. Clindamycin.
C. Quinupristin/dalfopristin.
D. Tigecycline.

Answer 3

Correct answer = B. Clindamycin is the safest option for the
treatment of MRSA in a pregnant patient. Doxycycline and
tigecycline can cross the placenta and can cause harm to
the fetus. Moreover, quinupristin/dalfopristin and tigecycline
are only available intravenously and would not be appropri-
ate for home antibiotic therapy for the given indication.

Question 4

39.4 A patient is being discharged from the hospital on a
3-week course of clindamycin. Which of the following
potential adverse effects should be discussed with her?
A. Hyperbilirubinemia.
B. Nephrotoxicity.
C. Clostridium difficile diarrhea.
D. Pseudotumor cerebri.

Answer 4

Correct answer = C. Clindamycin, among other antibiotics,
is associated with the development of C. difficile and pseu-
domembranous colitis due to disruption of normal gut flora,
particularly with prolonged therapy. Hyperbilirubinemia is
associated with quinupristin/dalfopristin, nephrotoxicity is
associated with aminoglycosides, and pseudotumor cerebri
can occur with tetracyclines.