1.
A 65-year-old woman was admitted to the emergency room with altered consciousness,
fever (103.6° F), nausea and vomiting.. Vital signs on admission were: blood pressure 90/50
mm Hg , pulse 115 bpm, respirations 20/min. Physical examination showed a patient in
obvious distress with stiff neck and positive Brudzinski's sign. Pupils were equal, poorly
reactive to light and papilledema was present. An empirical IV therapy was started with
ampicillin, ceftriaxone and vancomycin. Which of the following phrases best explains the
mechanism of action common to all the given drugs?
A. 
Misreading of mRNA template code
B. 
Inhibition of tetrahydrofolate synthesis
C. 
Inhibition of RNA polymerization
D. 
Blockade of peptidyl-tRNA translocation
E. 
Inhibition of peptidoglycan synthesis
2.
The diagram below depicts a simplified pathway for the synthesis and breakdown of
bacterial cell wall.
Which of the steps shown in the pathway is specifically inhibited by beta-lactam antibiotics?
A. 
B. 
C. 
D. 
3.
A 67-year-old man recently diagnosed with Legionnaires’ disease, started a treatment with
a macrolide antibiotic. Which of the following is the primary site of action of the drug on
bacterial cells?
A. 
The cytoplasmic membranes
B. 
C. 
D. 
E. 
F. 
G. 
4.
A 49-year-old woman, who was on vacation in the south of Italy, presented with fever,
headache and a small, button like skin ulcer, 5 mm in diameter, with a black center. The
diagnosis of Mediterranean spotted fever was made and the woman was prescribed
doxycycline. Which of the following molecular actions most likely mediated the therapeutic
effect of the drug in the patient ‘s disease?
A. 
Inhibition of DNA-dependent RNA polymerase
B. 
Blockade of the formation of ribosomal initiation complex
C. 
Blockade of transpeptidation reaction
D. 
Blockade of binding of aminoacyl-tRNA to bacterial ribosomes
E. 
Inhibition of transpeptidase enzymes
5.
A 28-year-old man recently diagnosed with Rocky Mountains spotted fever started a
treatment with doxycycline, two tablets daily. Which of the following is the primary site of
action of this drug?
A. 
B. 
C. 
30S subunit of bacterial ribosome
D. 
50S subunit of bacterial ribosome
E. 
6.
A 32-year-old woman on a vacation trip in east Asia was diagnosed with acute
conjunctivitis. A topical treatment with chloramphenicol was able to heal completely the
disease. Which of the following molecular actions most likely mediated the therapeutic
efficacy of the drug in the patient’s disease?
A. 
Inhibition of cross linking of linear peptidoglycan chains
B. 
Blockade of transpeptidation reaction of protein synthesis
C. 
Inhibition of relaxation of supercoiled bacterial DNA
D. 
Inhibition of ergosterol synthesis in the bacterial cell membrane
E. 
Misreading of the mRNA template in the ribosomal subunit
7.
A 60-year-old man was recently diagnosed with osteomyelitis due to staphylococci that
turned out to be vancomycin resistant. The patient started a therapy with two antibiotics of
the streptogramin group. Which of the following is the primary site of action of these
antibiotics?
A. 
B. 
C. 
D. 
E. 
F. 
G. 
The cytoplasmic membranes
8.
A 43-year-old woman recently diagnosed with urinary tract infection started a treatment
with trimethoprim-sulfamethoxazole. The inhibition of which of the following molecular
actions most likely mediated the therapeutic effect of the drug in the patient’s disease?
A. 
Assembly of DNA by DNA-dependent RNA polymerase
B. 
Replication of bacterial RNA
C. 
Synthesis of bacterial purines and pyrimidines
D. 
Translocation of the newly synthesized peptidyl-tRNA
E. 
Access of the aminoacyl-tRNA to the acceptor site
9.
A 33-year-old man was admitted to the hospital with the admitting diagnosis of bacterial
pneumonia. Further exams indicated that pneumonia was due to Mycoplasma pneumonia
and a treatment with a bacteriostatic antibiotic was started. The given antibiotic most likely
belonged to which of the following classes?
A. 
B. 
C. 
D. 
E. 
10.
A 34-year-old man recently diagnosed with streptococcal pharyngitis started a treatment
with amoxicillin, two tablets daily. Which of the following statements best explains a
prominent feature of the antibacterial action of this beta-lactam antibiotic?
A. 
It can inhibit bacterial growth but cannot kill bacteria
B. 
It increases with increasing concentration of the drug
C. 
It exhibits a long post antibiotic effect
D. 
It continues as long as the concentration is greater that MBC
E. 
It involves the inhibition of bacterial autolysins
11.
A 44-year-old man was admitted to the emergency room with the admitting diagnosis of
bacterial sepsis. Further exams indicated that Enterococcus faecium was the offending
pathogen and that the bacterium was vancomycin resistant. A treatment with linezolid was
started. Which of the following was most likely the site of action of this drug?
A. 
B. 
C. 
D. 
E. 
F. 
12.
A 34-year-old woman recently diagnosed with salpingitis due to Bacteroides fragilis
started a treatment with a drug that is reduced by anaerobes to a highly reactive nitro radical
anion able to damage bacterial DNA. Which of the following drugs did the patient most likely
take?
A. 
B. 
C. 
D. 
E. 
13.
A 48-year-old man recently diagnosed with campylobacter diarrhea started a treatment
with an antibiotic that blocks the transfer of peptidyl tRNA from the acceptor site to the
peptidyl site of the bacterial ribosome. The given antibiotic most likely belonged to which of
the following classes?
A. 
B. 
C. 
D. 
E. 
14.
A 42-year-old man recently diagnosed with mycoplasmal pneumonia started a treatment
with a fluoroquinolone, two tablet daily. Which of the following molecular actions most likely
mediated the therapeutic effect of the drug in the patient’s disease?
A. 
Inhibition of bacterial cell wall synthesis
B. 
Inhibition of relaxation of supercoiled bacterial DNA
C. 
Stimulation of synthesis of abnormal bacterial proteins
D. 
Inhibition of ergosterol synthesis in the bacterial cell membrane
E. 
Stimulation of bacterial DNA helicase
F. 
Stimulation of bacterial DNA-dependent RNA polymerase
15.
A 31-year-old woman, diagnosed with acute cystitis, started a treatment with
trimethoprim-sulfamethoxazole combination. Which of the following groups of steps shown
in the pathway below was most likely inhibited by that treatment?
A. 
B. 
C. 
D. 
E.