MCQs PHARMACOLOGY: Antimicrobials

1 Choose the antimicrobial which acts by interfering with DNA function in the bacteria:

A. Chloramphenicol

B. Ciprofloxacin

C. Streptomycin

D. Vancomycin


2 Which antibiotic is primarily bacteriostatic but becomes bactericidal at higher concentrations:

A. Erythromycin

B. Tetracycline

C. Chloramphenicol

D. Ampicillin


3 Select the antibiotic that has a high therapeutic index:

A. Streptomycin

B. Doxycycline

C. Cephalexin

D. Vancomycin.


4 The following organism is notorious for developing antimicrobial resistance rapidly:

A. Streptococcus pyogenes

B. Meningococcus

C. Treponema pallidum

D. Escherichia coli


5 Widespread and prolonged use of an antibiotic leads to emergence of drug resistant strains because antibiotics:

A. Induce mutation in the bacteria

B. Promote conjugation among bacteria

C. Allow resistant strains to propagate preferen-tially

D. All of the above


6 The most important mechanism of concurrent acquisition of multidrug resistance among bacteria is:

A. Mutation

B. Conjugation

C. Transduction

D. Transformation


7 Drug destroying type of bacterial resistance is important for the following antibiotics except:

A. Cephalosporins

B. Tetracyclines

C. Chloramphenicol

D. Aminoglycosides


8 Acquisition of inducible energy dependent efflux proteins by bacteria serves to:

A. Secrete exotoxins

B. Enhance virulance

C. Lyse host tissue

D. Confer antibiotic resistance



9 Methicillin resistant staphylococci do not respond to β-lactam antibiotics because:

A. They produce a β-lactamase which destroys methicillin and related drugs

B. They elaborate an amidase which destroys methicillin and related drugs

C. They have acquired penicillin binding pro-tein which has low affinity for β-lactam anti-biotics

D. They are less permeable to β-lactam anti-biotics


10 The following strategy will promote rather than curb emergence of antibiotic resistant micro-organisms:

A. Whenever possible use broad spectrum anti-biotics

B. Prefer a narrow spectrum antibiotic to a broad spectrum one if both are equally effective

C. Prefer short and intensive courses of anti-biotics

D. Use antibiotic combinations for prolonged therapy


11 Superinfections are more common with:

A. Use of narrow spectrum antibiotics

B. Short courses of antibiotics

C. Use of antibiotics that are completely absor-bed from the small intestines

D. Use of antibiotic combinations covering both gram positive and gram negative bacteria


12 The following organisms are frequently responsible for superinfections except:

A. Pseudomonas aeruginosa

B. Salmonella typhi

C. Clostridium difficile

D. Candida albicans


13 Select the antibiotic whose dose must be reduced in patients with renal insufficiency: A. Ampicillin

B. Chloramphenicol

C. Tobramycin

D. Erythromycin


14 Which antimicrobial should be avoided in patients of liver disease:

A. Tetracycline

B. Cotrimoxazole

C. Cephalexin

D. Ethambutol


15 What is break point concentration of an antibiotic:

A. Concentration at which the antibiotic lyses the bacteria

B. Concentration of the antibiotic which demar-kates between sensitive and resistant bacteria

C. Concentration of the antibiotic which over-comes bacterial resistance

D. Concentration at which a bacteriostatic anti-biotic becomes bactericidal

 

16 A bactericidal antibiotic has the following charac-teristic( s):
A. Pronounced postantibiotic effect
B. Large difference between MBC and MIC values
C. Efficacy in the absence of host defence
D. All of the above

17 Bacteriostatic drugs are unlikely to effect cure of bacterial infection in the following category of patients except:
A. Diabetic patients
B. Patients with allergic disorders
C. Patients on corticosteroid therapy
D. Subacute bacterial endocarditis patients

18 Antimicrobial drug combinations are aimed at achieving the following except:
A. Faster and more complete elimination of the infecting organism
B. Treat infection when nature and sensitivity of the infecting organism is not definite
C. Prevent emergence of resistant strains
D. Prevent superinfection

19 Which type of antimicrobial drug combination is most likely to exhibit antagonism:
A. Bactericidal + Bactericidal
B. Bactericidal + Bacteriostatic for a highly sensitive organism
C. Bactericidal + Bacteriostatic for a marginally sensitive organism
D. Bacteriostatic + Bacteriostatic

 

20 Select the drug combination which does not exhibit supraadditive synergism:
A. Nalidixic acid + Nitrofurantoin
B. Amoxicillin + Clavulanic acid
C. Pyrimethamine + Sulfadoxine
D. Sulfamethoxazole + Trimethoprim

21 Choose the condition which is mostly treated with a combination of antimicrobials:
A. Lobar pneumonia
B. Typhoid
C. Peritonitis
D. Syphilis

22 Prophylactic use of antibiotics is not justified in the following condition:
A. To prevent secondary infection in common cold
B. Thoroughly cleaned contaminated wound
C. Rheumatic fever in a child of 10 years
D. Catheterization of urethra in an elderly male

23 Antimicrobial prophylaxis is regularly warranted in the following:
A. Chronic obstructive lung disease patients
B. Neonates delivered by forceps
C. Anastomotic intestinal surgery
D. All of the above

24 Surgical antibiotic prophylaxis for clean elective sur-gery started just before operation should be conti-nued for:
A. One day
B. Three days
C. Five days
D. Seven days

 

25 Which of the following is not likely to be the cause of failure of antimicrobial therapy of an acute infection:
A. Improper selection of drug and dose
B. Acquisition of resistance during treatment
C. Failure to drain the pus
D. Uncontrolled diabetes mellitus

sulfonamiodes
1 That sulfonamides act by inhibiting folate synthesis in bacteria is supported by the following findings except: A. Paraaminobenzoic acid antagonises the action of sulfonamides
B. Methionine antagonises the action of sulfo-namides
C. Purines and thymidine present in pus anta-gonise the action of sulfonamides
D. Bacteria that utilise folic acid taken up from the medium are insensitive to sulfo-namides

2 Indicate the sulfonamide whose sodium salt yields a nearly neutral solution which is suitable for topical use in the eye:
A. Sulfadiazine
B. Sulfacetamide
C. Sulfadoxine
D. Sulfamoxole

3 A higher incidence of adverse effects to cotrim-oxazole occurs when this drug is used for:
A. Typhoid fever
B. Whooping cough
C. Pneumocystis carinii pneumonia in AIDS patients
D. Chancroid

 

4 The following is true of sulfonamides except:
A. They are more likely to produce crystalluria in alkaline urine in which they are less soluble
B. They are primarily metabolized by acetylation
C. They may exert bactericidal action in the urinary tract
D. Used alone, they have become therapeuti-cally unreliable for serious infections

5 Select the sulfonamide drug which is active against Pseudomonas and is used by topical application for prophylaxis of infection in burn cases:
A. Sulfadiazine
B. Silver sulfadiazine
C. Sulfadoxine
D. Sulfamethoxazole

6 Trimethoprim inhibits bacteria without affecting mam-malian cells because:
A. It does not penetrate mammalian cells
B. It has high affinity for bacterial but low affinity for mammalian dihydrofolate reduct-ase enzyme
C. It inhibits bacterial folate synthetase as well as dihydrofolate reductase enzymes
D. All of the above

7 Trimethoprim is combined with sulfamethoxazole in a ratio of 1:5 to yield a steady state plasma concen-tration ratio of:
A. Trimethoprim 1: Sulfamethoxazole 5
B. Trimethoprim 1: Sulfamethoxazole 10
C. Trimethoprim 1: Sulfamethoxazole 20
D. Trimethoprim 5: Sulfamethoxazole 1

 

8 Indicate the condition in which neither trimethoprim nor sulfamethoxazole alone are effective, but their combination cotrimoxazole is:
A. Prostatitis
B. Lymphogranuloma venereum
C. Pneumocystis carinii pneumonia
D. Bacillary dysentery

9 The following quinolone antimicrobial agent is not useful in systemic infections:
A. Lomefloxacin
B. Ofloxacin
C. Nalidixic acid
D. Pefloxacin

10 Indicate the enzyme(s) inhibited by fluoroquinolones:
A. Both 'A' and 'C'
B. Topoisomerase II
C. Topoisomerase IV
D. DNA gyrase

11 Select the antimicrobial drug which is used orally only for urinary tract infection or for bacterial diarrhoeas:
A. Nalidixic acid
B. Azithromycin
C. Bacampicillin
D. Pefloxacin

12 Nalidixic acid is primarily active against:
A. Cocci
B. Bacilli
C. Gram positive bacteria
D. Gram negative bacteria

 

13 The fluoroquinolones have improved over nalidixic acid in the following respect(s):
A. They have higher antimicrobial potency
B. They have extended antimicrobial spectrum
C. Development of bacterial resistance against them is slow and infrequent
D. All of the above

14 Adverse effects of ciprofloxacin are referable primarily to the following except:
A. Gastrointestinal tract
B. Kidney
C. Skin
D. Nervous system

15 Select the fluoroquinolone which has high oral bio-availability, longer elimination half-life and which does not inhibit metabolism of theophylline:
A. Norfloxacin
B. Pefloxacin
C. Lomefloxacin
D. Ciprofloxacin

16 A single oral dose of the following drug can cure most cases of uncomplicated gonorrhoea:
A. Ciprofloxacin
B. Cotrimoxazole
C. Spectinomycin
D. Doxycycline

17 Which fluoroquinolone has enhanced activity against gram positive bacteria and anaerobes:
A. Pefloxacin
B. Ciprofloxacin
C. Sparfloxacin
D. Norfloxacin

 

18 The most common mechanism of development of resistance to fluoroquinolones is:
A. Chromosomal mutation altering affinity of target site
B. Plasmid transfer
C. Acquisition of drug destroying enzyme
D. Acquisition of alternative metabolic path-way

19 Ciprofloxacin is not active against:
A. H.influenzae
B. E.coli
C. Enterobacter spp.
D. Bacteroides fragilis

20 Important microbiological features of ciprofloxacin include the following except:
A. Long postantibiotic effect
B. Marked suppression of intestinal anaerobes
C. MBC values close to MIC values
D. Slow development of resistance

21 Currently the drug of choice for emperic treatment of typhoid fever is:
A. Chloramphenicol
B. Cotrimoxazole
C. Ciprofloxacin
D. Ampicillin

22 The following drug may cure typhoid fever, but does not prevent development of carrier state:
A. Ciprofloxacin
B. Cotrimoxazole
C. Chloramphenicol
D. Ceftriaxone

 

23 The distinctive feature(s) of sparfloxacin compared to ciprofloxacin is/are:
A. Enhanced activity against gram positive bacteria
B. Lack of pharmacokinetic interaction with theophylline and warfarin
C. Higher incidence of phototoxic reaction
D. All of the above

24 In the treatment of typhoid fever, ciprofloxacin has the following advantage(s):
A. It is effective in nearly all cases
B. Early abetment of fever and other symptoms
C. Development of carrier state is unlikely
D. All of the above

25 Distinctive features of gatifloxacin include the following except:
A. Higher affinity for the enzyme topoisomerase IV
B. Activity restricted to gram negative bacteria
C. Potential to prolong QTc interval
D. Employed to treat community acquired pneumonia

26 The following fluoroquinolones have augmented activity against gram positive bacteria except:
A. Lomefloxacin
B. Levofloxacin
C. Gatifloxacin
D. Moxifloxacin

1 The beta lactam antibiotics include the following:
A. Cephalosporins
B. Monobactams
C. Carbapenems
D. All of the above

 

2 The most likely explanation of differing sensitivities of different bacteria to various penicillins is:
A. Differing susceptibilities of the various peni-cillins to β-lactamases produced by different bacteria
B. Differing affinities of penicillin binding pro-teins present in different bacteria towards various penicillins
C. Differing penetrability of various penicillins into different bacteria
D. Differing rates of cell wall synthesis by different bacteria

3 Penicillins interfere with bacterial cell wall synthesis by:
A. Inhibiting synthesis of N-acetyl muramic acid pentapeptide
B. Inhibiting conjugation between N-acetyl mu-ramic acid and N-acetyl glucosamine
C. Inhibiting transpeptidases and carboxy-peptidases which cross link the peptidogly-can residues
D. Counterfeiting for D-alanine in the bacterial cell wall

4 The characteristic feature(s) of penicillin G is/are:
A. It is unstable in aqueous solution
B. Its antibacterial action is unaffected by pus and tissue fluids
C. It is equally active against resting and multi-plying bacteria
D. Both ‘A’ and ‘B’ are correct

 

5 Gram negative organisms are largely insensitive to benzyl penicillin because:
A. They produce large quantities of penicillinase
B. They do not utilise
D-alanine whose incorpo-ration in the cell wall is inhibited by benzyl-penicillin
C. Benzyl penicillin is not able to penetrate deeper into the lipoprotein-peptidoglycan multilayer cell wall of gram negative bacteria
D. Both ‘A’ and ‘B’ are correct

6 The dominant pharmacokinetic feature of penicillin G is:
A. It is equally distributed extra- and intra-cellularly
B. It is rapidly secreted by proximal renal tubules
C. It has low oral bioavailability due to high first pass metabolism in liver
D. It does not cross blood–CSF barrier even when meninges are inflamed

7 The penicillin G preparation with the longest duration of action is:
A. Benzathine penicillin
B. Sodium penicillin
C. Potassium penicillin
D. Procaine penicillin

8 If a patient gives history of urticaria, itching and swel-ling of lips following injection of penicillin G, then:
A. He will develop similar reaction whenever penicillin is injected
B. He can be given ampicillin safely
C. He can be given oral phenoxymethyl penicil-lin safely
D. All natural and semisynthetic penicillins are contraindicated for him