MCQs-Antimicrobial Drugst Part 4 I Pharmacology KD Tripathi mcqs part 50

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50.1 The most important mechanism by which tetracycline antibiotics exert antimicrobial action is:

A. They chelate Ca2+ ions and alter permeability of bacterial cell membrane

B. They bind to 30S ribosomes and inhibit bacterial protein synthesis

C. They bind to 50S ribosomes and interfere with translocation of the growing peptide

chain in the bacteria

D. They interfere with DNA mediated RNA synthesis in bacteria

50.2 Select the most potent tetracycline antibiotic:

A. Demeclocycline

B. Oxytetracycline

C. Minocycline

D. Doxycycline

50.3 The following tetracycline has the potential to cause vestibular toxicity:

A. Minocycline

B. Demeclocycline

C. Doxycycline

D. Tetracycline

50.4 Mammalian cells are not inhibited by low concentrations

of tetracyclines that inhibit sensitive microorganisms because:

A. Host cells lack active transport mechanism for tetracyclines

B. Host cells actively pump out tetracyclines

C. Protein synthesizing apparatus of host cells has low affinity for tetracyclines

D. Both ‘A’ and ‘C’ are correct

50.5 Bacteria develop tetracycline resistance by the following mechanisms except:

A. Losing tetracycline concentrating mechanisms

B. Elaborating tetracycline inactivating enzyme

C. Synthesizing a ‘protection protein’ which

interferes with binding of tetracycline to the target site

D. Actively pumping out tetracycline that has entered the cell

50.6 An 8-year-old child presented with brownish discoloured

and deformed anterior teeth. History of having

received an antibiotic about 4 years earlier was

obtained. Which antibiotic could be responsible for the condition:

A. Chloramphenicol

B. Tetracycline

C. Erythromycin

D. Gentamicin

50.7 Choose the correct statement about tetracyclines:

A. Being broad spectrum antibioics they are dependable for empirical treatment of lifethreatening infections

B. Currently, they are not the first choice antibiotic for any specific infection

C. They reduce stool volume and duration of diarrhoea in cholera

D. The are preferred for treatment of anaerobic bacterial infections

50.8 The drug of choice for atypical pneumonia due to

Mycoplasma pneumoniae is:

A. Doxycycline

B. Ciprofloxacin

C. Ceftriaxone

D. Gentamicin

50.9 The most suitable tetracycline for use in a patient with impaired renal function is:

A. Tetracycline

B. Demeclocycline

C. Oxytetracycline

D. Doxycycline

50.10 Compared to older tetracyclines, doxycycline produces a

lower incidence of superinfection diarrhoea because:

A. It is completely absorbed in the small intestines so that drug concentration in the

colonic contents is low

B. It is inactivated by the gut microflora

C. It is not active against the microbes of the normal gut flora

D. It is a potent tetracycline and inhibits the superinfection causing microbes as well

50.11 Select the antibiotic(s) that can be used to treat

nonspecific urethritis due to Chlamydia trachomatis:

A. Azithromycin

B. Doxycycline

C. Clindamycin

D. Both 'A' and 'B' are correct

50.12 Tetracyclines are still the first choice drugs for the following disease:

A. Granuloma inguinale

B. Chancroid

C. Syphilis

D. Gonorrhoea in patients allergic to penicillin

 

50.13 Tetracyclines are active against the following gram

negative bacteria:

A. Salmonella typhi

B. Pseudomonas aeruginosa

C. Yersinia pestis

D. All of the above

50.14 A patient treated with capsule oxytetracycline 500

mg 6 hourly complained of epigastric pain. Which of

the following measures will you recommend to

counteract the side effect:

A. Take the capsules with milk

B. Take the capsules with meals

C. Take aluminium hydroxide gel 15 minutes before the capsules

D. None of the above measures is suitable.

Change the antibiotic if pain is distressing

50.15 A child presented with polyuria, weakness and fever.

On the basis of investigations he was labelled to be

suffering from Fancony syndrome. A history of taking

some old left over antibiotic capsules was obtained.

What could have been the antibiotic:

A. Tetracycline

B. Chloramphenicol

C. Ampicillin

D. Cephalexin

50.16 Chloramphenicol inhibits bacterial protein synthesis by:

A. Binding to 30S ribosome and inhibiting attachment of aminoacyl tRNA

B. Binding to 50S ribosome and preventing peptide bond formation

C. Binding to 50S ribosome and blocking translocation of peptide chain

D. Binding to both 30S and 50S ribosome and inducing misreading of mRNA code

50.17 Chloramphenicol is more active than tetracyclines against:

A. Bateroides fragilis

B. Treponema pallidum

C. Streptococci

D. Staphylococci

50.18 The following antibiotic penetrates blood-CSF barrier the best:

A. Erythromycin

B. Gentamicin

C. Tetracycline

D. Chloramphenicol

50.19 The most important mechanism by which gram negative

bacilli acquire chloramphenicol resistance is:

A. Decreased permeability into the bacterial cell

B. Acquisition of a plasmid encoded for chloramphenicol acetyl transferase

C. Lowered affinity of the bacterial ribosome for chloramphenicol

D. Switching over from ribosomal to mitochondrial protein synthesis

50.20 A premature neonate suffered respiratory distress

and was given an antibiotic 100 mg/kg/day orally.

Over the next two days his condition worsened, he

become dull, stopped feeding, developed abdominal

distention and an ashen gray appearance. Which is

the most likely antibiotic given to him:

A. Ampicillin

B. Chloramphenicol

C. Erythromycin

D. Ciprofloxacin

50.21 Combination therapy with two (or more) antimicrobials

is superior to monotherapy with any single effective

drug in case of the following diseases except:

A. Typhoid fever

B. Leprosy

C. AIDS

D. Subacute bacterial endocarditis

50.22 What is true of drug therapy of typhoid fever:

A. Combination of chloramphenicol with ciprofloxacin is superior to either drug alone

B. Ceftriaxone (i.v.) is one of the fastest acting and most dependable treatment

C. Prolonged treatment with chloramphenicol eradicates typhoid carrier state

D. All of the above are correct

50.23 What is the most important reason for the restricted use of systemic chloramphenicol:

A. Emergence of chloramphenicol resistance

B. Its potential to cause bone marrow depression

C. Its potential to cause superinfections

D. Its potential to inhibit the metabolism of many drugs

50.24 The primary reason why chloramphenicol is not

being used as the first line drug for typhoid fever in most areas is:

A. Toxic potential of chloramphenicol

B. Delayed defervescence with chloramphenicol

C. Delayed bacteriological cure with chloramphenicol

D. Spread of chloramphenicol resistance among S. typhi

50.25 Empiric therapy with chloramphenicol is valid in the following conditions except:

A. Urinary tract infection

B. Pelvic abscess

C. Endophthalmitis

D. Meningitis in a 4-year-old child

Ans:

50.1 B 50.2 C 50.3 A 50.4D 50.5 B 50.6 B 50.7 C 50.8 A 50.9D 50.10 A 50.11D 50.12 A 50.13 C 50.14D 50.15 A 50.16 B 50.17 A 50.18D 50.19 B 50.20 B 50.21 A 50.22 B 50.23 B 50.24D 50.25 A