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 synthesi

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 synthesi
by

1 Answer

Answer :

B. Acquisition of a plasmid encoded for chloramphenicol acetyl transferas
by

Related questions

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

Description : 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 ... bacterial ribosome for chloramphenicol (d) Switching over from ribosomal to mitochondrial protein synthesis

Last Answer : Ans: B

The most important mechanism of bacterial resistance to an aminoglycoside antibiotic is (a) Plasmid mediated acquisition of aminoglycoside conjugating enzyme (b) Mutational acquisition of aminoglycoside hydrolyzing enzyme (c) Mutation reducing affinity of ribosomal protein for the antibiotic (d) Mutational loss of porin channels

Description : The most important mechanism of bacterial resistance to an aminoglycoside antibiotic is (a) Plasmid mediated acquisition of aminoglycoside conjugating enzyme (b) Mutational acquisition of aminoglycoside ... affinity of ribosomal protein for the antibiotic (d) Mutational loss of porin channels

Last Answer : Ans: A

The most important mechanism of bacterial resistance to an aminoglycoside antibiotic is: A. Plasmid mediated acquisition of aminoglycoside conjugating enzyme B. Mutational acquisition of aminoglycoside hydrolysing enzyme C. Mutation reducing affinity of ribosomal protein for the antibiotic D. Mutational loss of porin channels

Description : The most important mechanism of bacterial resistance to an aminoglycoside antibiotic is: A. Plasmid mediated acquisition of aminoglycoside conjugating enzyme B. Mutational acquisition of aminoglycoside ... affinity of ribosomal protein for the antibiotic D. Mutational loss of porin channels

Last Answer : A. Plasmid mediated acquisition of aminoglycoside conjugating enzyme

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 pathway

Description : 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 pathway

Last Answer : A. Chromosomal mutation altering affinity of target site

The primary mechanism underlying the resistance of gram-positive organisms to macrolide antibiotics is (a) Methylation of binding sites on the 50S ribosomal subunit (b) Formation of esterases that hydrolyze the lactone ring (c) Increased activity of efflux mechanisms (d) Formation of drug-inactivating acetyltranferases (e) Decreased drug permeability of the cytoplasmic membrane

Description : The primary mechanism underlying the resistance of gram-positive organisms to macrolide antibiotics is (a) Methylation of binding sites on the 50S ribosomal subunit (b) Formation of ... ) Formation of drug-inactivating acetyltranferases (e) Decreased drug permeability of the cytoplasmic membrane

Last Answer : Ans: A

Select the antibiotic which inhibits bacterial protein synthesis by interfering with translocation of elongating peptide chain from acceptor site back to the peptidyl site of the ribosome so that ribosome does not move along the mRNA and the peptide chain is prematurely terminated: A. Chloramphenicol B. Erythromycin C. Tetracycline D. Streptomycin

Description : Select the antibiotic which inhibits bacterial protein synthesis by interfering with translocation of elongating peptide chain from acceptor site back to the peptidyl site of the ribosome so that ... chain is prematurely terminated: A. Chloramphenicol B. Erythromycin C. Tetracycline D. Streptomycin

Last Answer : B. Erythromycin

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

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

Semisynthetic penicillins developed so far have overcome the following drawbacks of benzylpenicillin except: A. Lack of efficacy against gram negative bacilli B. Susceptibility to bacterial penicillinase C. Inactivation by gastric acid D. Potential to cause hypersensitivity reactions

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Last Answer : D. Potential to cause hypersensitivity reactions

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

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

Peptidyl transferase activity of 50 S ribosomal subunits is inhibited by (A) Rifampicin (B) Cycloheximide (C) Chloramphenicol (D) Erythromycin

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Last Answer : Answer : C

Drug destroying type of bacterial resistance is important for the following antibiotics except: A. Cephalosporins B. Tetracyclines C. Chloramphenicol D. Aminoglycosides

Description : Drug destroying type of bacterial resistance is important for the following antibiotics except: A. Cephalosporins B. Tetracyclines C. Chloramphenicol D. Aminoglycosides

Last Answer : B. Tetracyclines

Features of clindamycin include the following: A. It is primarily active against aerobic gram negative bacilli B. It can be used topically to treat infected acne vulgaris C. It is not absorbed orally D. It is used to treat pseudomembranous enterocolitis

Description : Features of clindamycin include the following: A. It is primarily active against aerobic gram negative bacilli B. It can be used topically to treat infected acne vulgaris C. It is not absorbed orally D. It is used to treat pseudomembranous enterocolitis

Last Answer : B. It can be used topically to treat infected acne vulgaris

Aminoglycoside antibiotics have the following property common to all members: A. They are primarily active against aerobic gram negative bacilli B. They are more active in acidic medium C. They readily enter cells and are distributed in total body water D. They are nearly completely metabolized in liver

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Last Answer : A. They are primarily active against aerobic gram negative bacilli

Sulbactam differs from clavulanic acid in that: A. It is not a progressive inhibitor of β-lactamase B. It does not inhibit β-lactamase produced by gram negative bacilli C. It is quantitatively more potent D. It per se inhibits N.gonorrhoeae

Description : Sulbactam differs from clavulanic acid in that: A. It is not a progressive inhibitor of β-lactamase B. It does not inhibit β-lactamase produced by gram negative bacilli C. It is quantitatively more potent D. It per se inhibits N.gonorrhoeae

Last Answer : D. It per se inhibits N.gonorrhoeae

Choose the semisynthetic penicillin which has an extended spectrum of activity against many gram negative bacilli, is acid resistant but not penicillinase resistant: A. Cloxacillin B. Amoxicillin C. Phenoxymethyl penicillin D. Piperacillin

Description : Choose the semisynthetic penicillin which has an extended spectrum of activity against many gram negative bacilli, is acid resistant but not penicillinase resistant: A. Cloxacillin B. Amoxicillin C. Phenoxymethyl penicillin D. Piperacillin

Last Answer : B. Amoxicillin

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

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The most important mechanism by which tetracycline antibiotics exert antiimicrobial 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

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The most important mechanism of concurrent acquisition of multidrug resistance among bacteria is: A. Mutation B. Conjugation C. Transduction D. Transformation

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Antibacterial agents can be classified with regard to their structure, mechanism of action, and activity pattern against various types of bacterial pathogens. Which of the following statement(s) is/are true concerning antimicrobial classes? a. Penicillins and cephalosporins share the compound structure of a b-lactam ring which binds to bacterial division plate proteins b. Tetracyclines and macrolides such as erythromycin inhibit bacterial ribosomal activity and therefore protein synthesis c. Aminoglycosides act in a similar fashion to tetracyclines and therefore are both bacteriostatic d. Sulfonamides and trimethoprim act synergistically to inhibit purine synthesis

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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

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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

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Indicate the attribute that is common to both polymyxin B and bacitracin: A. Both are active against gram negative bacteria B. Both are too toxic for systemic use C. Both act by inhibiting bacterial cell wall synthesis D. Both a

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Metronidazole is used in peridontal abscess because of activity against: A. Entamoeba histolytica B. Giardia lamblia C. Anaerobic bacilli D. Aerobic gram positive cocci

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Peptidyl transferase activity is located in (A) Elongation factor (B) A charged tRNA molecule (C) Ribosomal protein (D) A soluble cytosolic protein

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The following is true of vancomycin except: A. It is a bactericidal antibiotic active primarily against gram positive bacteria B. It acts by inhibiting bacterial protein synthesis C. It is an alternative to penicillin for enterococcal endocarditis D. It can cause deafness as a dose related toxicity

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

Description : Penicillins interfere with bacterial cell wall synthesis by: A. Inhibiting synthesis of N-acetyl muramic acid pentapeptide B. Inhibiting conjugation between N-acetyl muramic acid and N-acetyl ... cross link the peptidoglycan residues D. Counterfeiting for D-alanine in the bacterial cell wall

Last Answer : C. Inhibiting transpeptidases and carboxypeptidases which cross link the peptidoglycan residues

The mechanism of antibacterial action of tetracycline involves (a) Binding to a component of the 50S ribosomal subunit (b) Inhibition of translocase activity (c) Blockade of binding of aminoacyl – tRNA to bacterial ribosomes (d) Selective inhibition of ribosomal peptidyl transferases (e) Inhibition of DNA–dependent RNA polymerase

Description : The mechanism of antibacterial action of tetracycline involves (a) Binding to a component of the 50S ribosomal subunit (b) Inhibition of translocase activity (c) Blockade of binding of ... (d) Selective inhibition of ribosomal peptidyl transferases (e) Inhibition of DNA-dependent RNA polymerase

Last Answer : Ans: C

The most likely mechanism of antihypertensive action of thiazide diuretics in the long-term is: A. Reduction of circulating blood volume B. Reduction in cardiac output C. Decreased sympathetic tone D. Reduction in total peripheral vascular resistance and improved compliance of resistance vessels

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Last Answer : D. Reduction in total peripheral vascular resistance and improved compliance of resistance vessels

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

Description : 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

Last Answer : B. Its potential to cause bone marrow depression

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

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Last Answer : B. It has high affinity for bacterial but low affinity for mammalian dihydrofolate reductase enzyme

A 67-year-old male presents with an intraabdominal abscess secondary to perforated sigmoid diverticulitis. The following statement(s) is/are true concerning his intraabdominal abscess. a. Culture will likely reveal a solitary organism b. Both aerobic and anaerobic islets are encountered in 50% of specimens c. The most common aerobic islet will be likely E. coli and other gram-negative enteric bacilli d. The most common anaerobic islet will be a Bacteroides species

Description : A 67-year-old male presents with an intraabdominal abscess secondary to perforated sigmoid diverticulitis. The following statement(s) is/are true concerning his intraabdominal abscess. a. Culture will ... gram-negative enteric bacilli d. The most common anaerobic islet will be a Bacteroides species

Last Answer : Answer: b, c, d Typically an intraabdominal infection results in perforation of a hollow viscus and the ensuing contamination of a normally sterile peritoneal cavity. The normal ... Bacteroides species (especially B. fragilis, Clostridium), and anaerobic cocci are most consistently isolated

The complement system consists of a series of serum proteins that exist in a quiescent or very low-level state of activation in the uninfected host. Which of the following statement(s) is/are true concerning complement activation? a. The alternate (properdin) pathway of complement activation can occur directly through contact with fungal or bacterial cell wall compounds b. Complement component fragments may serve to decrease vascular permeability c. Excessive complement activation can produce deleterious effects d. Fragments of certain complement components serve as chemoattractants to additional cellular components of the host defense mechanism

Description : The complement system consists of a series of serum proteins that exist in a quiescent or very low-level state of activation in the uninfected host. Which of the following ... certain complement components serve as chemoattractants to additional cellular components of the host defense mechanism

Last Answer : Answer: a, c, d Complement activation can occur through either classic or alternate (properdin) pathways, both of which eventuate in deposition of terminal complement pathway components on the ... and release of lysosomal enzymes that can directly damage certain target tissues, such as the lung

As an antitubercular drug, isoniazid has the following advantages except: A. It is tuberculocidal B. It acts on both extra and intracellular bacilli C. Tubercle bacilli do not develop resistance against it D. It is cheap

Description : As an antitubercular drug, isoniazid has the following advantages except: A. It is tuberculocidal B. It acts on both extra and intracellular bacilli C. Tubercle bacilli do not develop resistance against it D. It is cheap

Last Answer : C. Tubercle bacilli do not develop resistance against it

Bacteria become erythromycin resistant by the following mechanisms except: A. Becoming less permeable to erythromycin B. Elaborating an erythromycin esterase enzyme C. Elaborating a ‘protection protein’ which blocks the erythromycin binding site D. Altering the ribosomal binding site through a methylase enzyme

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Last Answer : C. Elaborating a ‘protection protein’ which blocks the erythromycin binding site

The following drug displaces plasma protein bound phenytoin as well as decreases its metabolism: A. Carbamazepine B. Sodium valproate C. Cimetidine D. Chloramphenicol

Description : The following drug displaces plasma protein bound phenytoin as well as decreases its metabolism: A. Carbamazepine B. Sodium valproate C. Cimetidine D. Chloramphenicol

Last Answer : B. Sodium valproate

Difference in Gram positive and Gram negative bacteria is due to (a) cell wall (b) cell membrane (c) ribosome (d) cytoplasm.

Description : Difference in Gram positive and Gram negative bacteria is due to (a) cell wall (b) cell membrane (c) ribosome (d) cytoplasm.

Last Answer : (a) cell wall

Difference in Gram positive and Gram negative bacteria is due to (a) cell wall (b) cell membrane (c) ribosome (d) cytoplasm.

Description : Difference in Gram positive and Gram negative bacteria is due to (a) cell wall (b) cell membrane (c) ribosome (d) cytoplasm.

Last Answer : (a) cell wall

Binding of formylmehtionyl tRNA to 30 S ribosomal subunit of prokaryotes is inhibited by (A) Streptomycin (B) Chloramphenicol (C) Erythromycin (D) Mitomycin

Description : Binding of formylmehtionyl tRNA to 30 S ribosomal subunit of prokaryotes is inhibited by (A) Streptomycin (B) Chloramphenicol (C) Erythromycin (D) Mitomycin

Last Answer : Answer : A

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

Description : 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 ... C. Delayed bacteriological cure with chloramphenicol D. Spread of chloramphenicol resistance among S. typhi

Last Answer : D. Spread of chloramphenicol resistance among S. typhi

Of the following which is the most important mechanism of concurrent acquisition of multidrug resistance among bacteria ? (a) Mutation (b) Conjugation (c) Transduction (d) Transformation

Description : Of the following which is the most important mechanism of concurrent acquisition of multidrug resistance among bacteria ? (a) Mutation (b) Conjugation (c) Transduction (d) Transformation

Last Answer : Ans: B

Under certain circumstances, the gut may become a source of sepsis and serve as the motor of systemic inflammatory response syndrome. Microbial translocation is the process by which microorganisms migrate across the mucosal barrier to invade the host. Which of the following mechanisms can promote bacterial translocation? a. An increased number of gut bacteria b. Altered intestinal mucosal permeability c. Decreased host defense mechanisms d. Lack of enteral feeding

Description : Under certain circumstances, the gut may become a source of sepsis and serve as the motor of systemic inflammatory response syndrome. Microbial translocation is the process by which microorganisms ... intestinal mucosal permeability c. Decreased host defense mechanisms d. Lack of enteral feeding

Last Answer : Answer: a, b, c, d 99 Translocation is promoted in three general ways: 1) altered permeability of the intestinal mucosa as caused by shock, sepsis, distant injury, or cell toxins; 2) ... trauma patient d. Fifty percent of non-nitrogen caloric requirements should be provided in the form of fat

Mechanism by which adrenaline can prolong the duration of local anesthesia a) Decreased permeability of the vascular endothelium b) Precipitation of lidocaine c) Changing the pH of the solution d) Local Vasoconstriction

Description : Mechanism by which adrenaline can prolong the duration of local anesthesia a) Decreased permeability of the vascular endothelium b) Precipitation of lidocaine c) Changing the pH of the solution d) Local Vasoconstriction

Last Answer : d) Local Vasoconstriction 

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 incorporation in the cell wall is inhibited by benzylpenicillin 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

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Last Answer : . Benzyl penicillin is not able to penetrate deeper into the lipoprotein-peptidoglycan multilayer cell wall of gram negative bacteria

Erythromycin binds to 50 S ribosomal sub unit and (A) Inhibits binding of amino acyl tRNA (B) Inhibits Peptidyl transferase activity (C) Inhibits translocation (D) Causes premature chain termination

Description : Erythromycin binds to 50 S ribosomal sub unit and (A) Inhibits binding of amino acyl tRNA (B) Inhibits Peptidyl transferase activity (C) Inhibits translocation (D) Causes premature chain termination

Last Answer : Answer : C

Peptidyl transferase activity is present in (A) 40 S ribosomal subunit (B) 60 S ribosomal subunit (C) eEF-2 (D) Amino acyl tRNA

Description : Peptidyl transferase activity is present in (A) 40 S ribosomal subunit (B) 60 S ribosomal subunit (C) eEF-2 (D) Amino acyl tRNA

Last Answer : Answer : B

In prokaryotes, chloramphenicol (A) Causes premature release of the polypeptide chain (B) Causes misreading of the mRNA (C) Depolymerises DNA (D) Inhibits peptidyl transferase activity

Description : In prokaryotes, chloramphenicol (A) Causes premature release of the polypeptide chain (B) Causes misreading of the mRNA (C) Depolymerises DNA (D) Inhibits peptidyl transferase activity

Last Answer : Answer : A

In mammalian cells, ribosomal RNA is produced mainly in the (A) Nucleus (B) Nucleolus (C) Ribosome (D) Golgi apparatus

Description : In mammalian cells, ribosomal RNA is produced mainly in the (A) Nucleus (B) Nucleolus (C) Ribosome (D) Golgi apparatus

Last Answer : Answer : B

Bactericidal action of aminoglycoside antibiotics is due to: A. Inhibition of bacterial protein synthesis B. Alteration of bacterial cell membrane permeability C. Damage to bacterial cell wall D. Inhibition of bacterial oxidative metabolism

Description : Bactericidal action of aminoglycoside antibiotics is due to: A. Inhibition of bacterial protein synthesis B. Alteration of bacterial cell membrane permeability C. Damage to bacterial cell wall D. Inhibition of bacterial oxidative metabolism

Last Answer : B. Alteration of bacterial cell membrane permeability

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

Description : 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

Last Answer : B. Acquisition of resistance during treatment