Pharmacology: MCQs on Antimicrobial Agents-II

Multiple Choice Questions on Antimicrobial Agents

1) Which of the following antibiotics acts by inhibiting nucleic acid synthesis?
a) Cephalosporin
b) Quinolones
c) Penicillin

d) Sulphonamides

2) Followings are the second-generation quinolones, except?
a) Ciprofloxacin

b) Enoxacin
c) Gatifloxacin

d) Ofloxacin

3) Which of the followings are the drug interactions of quinolones is correct?
a) Antacids and calcium supplements decrease the absorption of quinolones
b) Antacids, and calcium supplements increase absorption of quinolones

c) Increased metabolism of warfarin and caffeine
d) Quinolones enhance the metabolism of theophylline

4) The mechanism of action of Trimethoprim is:
a) Activation of enzyme dihydrofolate reductase
b) Activation of enzyme dihydrofolate reductase
c) Inhibition of enzyme dihydrofolate reductase
d) Inhibition of enzyme dihydropteroate synthetase

5) All of the following combinations are true, except: 

a) Ciprofloxacin: inhibition of DNA gyrase
b) Erythromycin: inhibition of 50s protein synthesis

c) Polymyxin B: inhibition of 50s protein synthesis
d) Sulphonamide: inhibition of folic acid

6) Cotrimoxazole is a combination of drugs
a) Sulphonamide + Chloramphenicol
b) Sulphonamide + Lincomycin
c) Sulphonamide + Tetracycline

 d) Sulphonamide + Trimethoprim

7) Following adverse effects shown by the corresponding drugs are true, except?
a) Chloramphenicol: gray baby syndrome
b) Cefoperazone: disulfiram-like reactions
c) Tetracycline: Fanconi syndrome
d) Sulphonamide: red man syndrome

8) The following statement about quinolones is true, except?
a) Inhibition of DNA gyrase
b) Gemifloxacin and Clinafloxacin are 4th generation quinolone
c) Norfloxacin is 1st generation quinolone and used in the treatment of UTI
d) Second generation quinolone has increased activity against gram-positive bacteria including S. pneumoniae

9) Ciprofloxacin should not be used with theophylline because..................................................... 

a) Decreases absorption of theophylline

b) Decreases the efficacy of ciprofloxacin
c) It increases the toxicity of theophylline
d) It decreases the efficacy of theophylline

10) Prolonged therapy of …………………………… leads to the development of pseudomembranous colitis
a) Amikacin
b) Clindamycin
c) Streptomycin
d) Vancomycin

11) By binding to the fungal ergosterol and altering its cellular permeability is the mechanism of action of ……………………….
a) Amphotericin B

b) Griseofulvin
c) Clotrimazole
d) Ketoconazole

12) Most commonly used topical antifungal for suppression of local candida infection is …………………........
a) Fluconazole

b) Flucytosine

c) Nystatin
d) Miconazole

13) The type of drug interactions between flucytosine and amphotericin B is ………………………
a) Antagonism

b) Additive
c) Potentiation
d) Synergism

14) Which antifungal acts by non-competitive inhibition of squalene epoxidase thereby inhibiting ergosterol synthesis?
a) Flucytosine
b) Griseofulvin
c) Ketoconazole
d) Terbinafine

15) For the treatment of tinea cruris and tinea corporis, which topical allylamine(s) can be used?
a) Terbinafine
b) Naftifine
c) Both
d) None of the above

16) Gynecomastia and menstrual irregularities are the adverse effects of ………………............
a) Terbinafine
b) Flucytosine
c) Griseofulvin
d) Ketoconazole

17)All of the followings are the correct combination of drugs and their mechanism of action, Except
a) Polyenes: binds to and disrupt the fungal cell membrane
b) Griseofulvin: blocks intracellular microtubules
c) Allylamines: inhibition of squalene epoxidase and blocks ergosterol formation in the cell membrane
d) Flucytosine: inhibition of cytochrome P450 dependent 14 α-demethylase and blocks ergosterol formation in the cell membrane

18) Flucytosine acts by
a) Inhibition of thymidylate synthetase leading to inhibition of DNA synthesis
b) Disruption of the mitotic spindle during metaphase by interacting with fungal microtubules
c) Inhibition of squalene epoxidase and blocks ergosterol formation in the cell membrane
d) None of the above

19) The most potent azoles antifungal is ………………….
a) Itraconazole
b) Fluconazole
c) Ketoconazole
d) Miconazole

20) Followings are the drug interactions of Ketoconazole, except?
a) Inhibition of the metabolism of cyclosporine thereby increasing its toxicity
b) Enhanced metabolism of Astemizole and Terfenadine thereby decreasing arrhythmias
c) Cimetidine interferes with Ketoconazole absorption by increasing gastric pH
d) Rifamycins increase Ketoconazole hepatic metabolism

Multiple Choice Answers:
1-b) Quinolones
2-c) Gatifloxacin
3-a) Antacids, and calcium supplements decrease the absorption of quinolones
4-c) Inhibition of enzyme dihydrofolate reductase
5-c) Polymyxin B: inhibition of 50s protein synthesis
6-d) Sulphonamide + Trimethoprim
7-d) Sulphonamide: red man syndrome
8-d) Second generation quinolone has increased activity against gram-positive bacteria including S. pneumoniae
9-c) It increases the toxicity of theophylline
10-b) Clindamycin
11-a) Amphotericin B
12-c) Nystatin
13-d) Synergism
14-d)Terbinafine
15-c) Both
16-d) Ketoconazole
17-d)  Flucytosine: inhibition of cytochrome P450 dependent 14 α-demethylase and blocks ergosterol formation in the cell membrane
18-a) Inhibition of thymidylate synthetase leading to inhibition of DNA synthesis
19-a) Itraconazole
20-b) Enhanced metabolism of Astemizole and Terfenadine thereby decreasing arrhythmias