Drug Resistance Mechanisms & Superinfection

DRUG RESISTANCE MECHANISMS & SUPERINFECTION

Q. 1

Drug resistance transfer by bacteriophage involves-

 A

Transduction

 B

Conjugation

 C

Transformation

 D

Convocation

Q. 1

Drug resistance transfer by bacteriophage involves-

 A

Transduction

 B

Conjugation

 C

Transformation

 D

Convocation

Ans. A

Explanation:

Ans. is ‘a’ i.e., Transduction


Q. 2

Multidrug resistance is transfered among bacteria through plasmids by –

 A

Transduction

 B

Transversion

 C

Conjugation

 D

Transformation

Q. 2

Multidrug resistance is transfered among bacteria through plasmids by –

 A

Transduction

 B

Transversion

 C

Conjugation

 D

Transformation

Ans. C

Explanation:

Ans. is ‘c’ i.e., Conjugation


Q. 3

Transfer of drug resistance in staphylococcus is by‑

 A

Transduction

 B

Transformation

 C

Conjugation

 D

a and c both

Q. 3

Transfer of drug resistance in staphylococcus is by‑

 A

Transduction

 B

Transformation

 C

Conjugation

 D

a and c both

Ans. D

Explanation:

Ans. is ‘a > c’ i.e., Transduction > Conjugation

.   Production of 13-lactamase is usually controlled by plasmids which are transmitted by transduction (more common) or conjugation.

Quiz In Between


Q. 4

The most common mechanism of drug resistance in staphylococci ‑

 A

Conjugation

 B

Plasmids

 C

Transduction

 D

Translation

Q. 4

The most common mechanism of drug resistance in staphylococci ‑

 A

Conjugation

 B

Plasmids

 C

Transduction

 D

Translation

Ans. C

Explanation:

Ans. is ‘c’ i.e., Transduction 

.   Production of b-lactamase is usually controlled by plasmids which are transmitted by transduction (most common) or conjugation (some times).


Q. 5

Microbial killing by an antibiotic below its `Minimum inhibitory concentration’ is known as?

 A

Concentration dependent killing

 B

Time dependent killing      

 C

Sequential blockade

 D

Post antibiotic effect

Q. 5

Microbial killing by an antibiotic below its `Minimum inhibitory concentration’ is known as?

 A

Concentration dependent killing

 B

Time dependent killing      

 C

Sequential blockade

 D

Post antibiotic effect

Ans. D

Explanation:

Ans. is ‘d’ i.e., Post antibiotic effect

Post antibiotic effect

o Post antibiotic effect (PAE) is a persistent suppression of microbial growth that occurs after levels of antibiotic have fallen below the MIC.

o Antimicrobial drugs exhibiting a long PAE (several hours) often require only one dose per day. For example aminoglycosides and fluoroquinolones, exhibit a long PAE, particularly against gram negative bacteria.


Q. 6

The persistent suppression of bacterial growth that may occur after limited exposure to some antimicrobial drug is called?

 A

Time dependent killing

 B

Concentration dependent killing

 C

Post antibiotic effect

 D

Sequential blockade

Q. 6

The persistent suppression of bacterial growth that may occur after limited exposure to some antimicrobial drug is called?

 A

Time dependent killing

 B

Concentration dependent killing

 C

Post antibiotic effect

 D

Sequential blockade

Ans. C

Explanation:

Ans. is ‘c’ i.e., Post antibiotic effect

Quiz In Between


Q. 7

Which amongst the following antimicrobials exhibits a long post antibiotic effect –

 A

Quinolones

 B

Macrolides

 C

Beta-lactams

 D

Oxazolidinones

Q. 7

Which amongst the following antimicrobials exhibits a long post antibiotic effect –

 A

Quinolones

 B

Macrolides

 C

Beta-lactams

 D

Oxazolidinones

Ans. A

Explanation:

Ans. is ‘a’ i.e., Quinoones

o Post-antibiotic effect is seen with quinolones (fluoroquinolones) and aminoglycosides.


Q. 8

Multiple drug resistance is transferred through –

 A

Transduction

 B

Transformation

 C

Conjugation

 D

Mutation

Q. 8

Multiple drug resistance is transferred through –

 A

Transduction

 B

Transformation

 C

Conjugation

 D

Mutation

Ans. C

Explanation:

Ans. is ‘c’ i.e., Conjugation

Resistance to multiple drugs is transmitted by R factor (plasmid)

o R factor is transferred from one bacterium to other by conjugation.

o Transduction and mutation usually cause resistance to one drug.

o Transformation is not involved significantly in drug resistance.


Q. 9

Which of the following regarding bacterial drug resistance is not true –

 A

Most bacterial drug resistance is due to production of penicillin degrading enzymes

 B

Plasmid mediated resistance is always transmitted vertically

 C

Complete elimination of target produces resistance to vancomycin

 D

Alteration in target protein leads to pneumococcal resistannce

Q. 9

Which of the following regarding bacterial drug resistance is not true –

 A

Most bacterial drug resistance is due to production of penicillin degrading enzymes

 B

Plasmid mediated resistance is always transmitted vertically

 C

Complete elimination of target produces resistance to vancomycin

 D

Alteration in target protein leads to pneumococcal resistannce

Ans. B

Explanation:

Ans. is ‘b’ i.e., Plasmid mediated resistance is always transmitted vertically

o Here is little information about vertical and horizontal gene transfer.

i)  Horizontal (lateral) gene transfer :- is the process in which an organism incorporates genetic material from another organism without being the offspring of that organism. Examples include conjugation, transduction and transformation.

ii) Vertical gene transfer :- is the process in which an organism receives genetic material from its parent.

o Most of the drug resistance (including plasmid mediated) are acquired by horizontal transfer. Example is ‘R’ factor (a plasmid) which is responsible for multiple drug resistance transfer by conjugation.

  • So option b is absolutely incorrect.

About other options

  • Most common mechanism of penicillin resistance is the production of penicillin degrading enzymes. o Vancomycin resistance may be due to :‑
  1. Synthesis of low affinity precursors, in which the C terminal D- Ala residue is replaced by D- Lactate (D-Lac) or D- serine (D-Ser), thus modifying the vancomycin-binding target.
  2. Elimination of the high affinity precursors that are normally produced by the host, thus removing the vancomycin- binding target.

o The molecular basis of penicillin resistance in S. pneumoniae is the alteration of penicillin binding proteins (PBPs) by transformation and horizontal transfer of DNA from related Sterptococcal species.

Quiz In Between


Q. 10

Extended activity of ii-lactamases inactivate

 A

Cephalosporins-III generation

 B

Macrolides

 C

Quinolone

 D

Aminoglycosides

Q. 10

Extended activity of ii-lactamases inactivate

 A

Cephalosporins-III generation

 B

Macrolides

 C

Quinolone

 D

Aminoglycosides

Ans. A

Explanation:

Ans. is ‘a’ i.e., Cephalosporins-III generation

ESBL are lactamases that mediate resistance (by hydrolyzing) to extended spectrum (third generation) cephalosporins, penicillins and monobactams (e.g. aztreonam).


Q. 11

All of the following are ture regarding cephalosporins except –

 A

Bactericidal agents

 B

Active against only gram negative bacteria

 C

IIIrd generation are resistant to beta-lactamases from gram negative bacteria

 D

Ceftriaxone is administered parenterally

Q. 11

All of the following are ture regarding cephalosporins except –

 A

Bactericidal agents

 B

Active against only gram negative bacteria

 C

IIIrd generation are resistant to beta-lactamases from gram negative bacteria

 D

Ceftriaxone is administered parenterally

Ans. B

Explanation:

Ans. is ‘b’ i.e., Active against olny gram negative bacteria

Cephalosporins are active against gram positive as well as gram negative bacteria, and are bactericidal.

o Ceftriaxone is a parentral cephalosporin.

o Third generation cephalosporins are highly resistant to beta-lactamases from gram negative bacteria.


Q. 12

Which of the following is not true regarding tetracycline –

 A

It is not teratogenic

 B

It can cause tooth discoloration

 C

It can result in superinfection

 D

It can lead to pseudomembranous colitis.

Q. 12

Which of the following is not true regarding tetracycline –

 A

It is not teratogenic

 B

It can cause tooth discoloration

 C

It can result in superinfection

 D

It can lead to pseudomembranous colitis.

Ans. A

Explanation:

Ans. is ‘a’ i.e., It is not teratogenic

o Tetracycline is teratogenic – causes discoloration and defects of teeth and altered bone growth of the fetus.

o Tetracycline can cause superinfection (including pseudomembranous colitis).

Quiz In Between


Q. 13

Drug resistance in Tuberculosis is due to ‑

 A

Transformation

 B

Transduction

 C

Conjugation

 D

Mutation

Q. 13

Drug resistance in Tuberculosis is due to ‑

 A

Transformation

 B

Transduction

 C

Conjugation

 D

Mutation

Ans. D

Explanation:

Ans. is ‘d’ i.e., Mutation


Q. 14

Antibiotic with Time-dependent killing and post antibiotic effect?

 A

Fluoroquinolones

 B

Beta lactam antibiotics

 C

Erythromycin

 D

Clindamycin

Q. 14

Antibiotic with Time-dependent killing and post antibiotic effect?

 A

Fluoroquinolones

 B

Beta lactam antibiotics

 C

Erythromycin

 D

Clindamycin

Ans. D

Explanation:

Ans. d. Clindamycin

Quiz In Between



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