Inhibition of bacterial DNA synthesis occurs by
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11%
Polymyxin
5%
Chloramphenicol
79%
Quinolones
5%
Cephalosporins
The following mechanisms of antimicrobial agents are true EXCEPT:
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73%
Tetracyclines and aminoglycosides inhibit DNA gyrase
7%
Sulphonamides compete with para-amino benzoic acid
13%
Polymyxin and amphotericin 8 interfere with cell membrane functions
7%
Trimethoprim inhibits the dihydrofolic acid reductase enzyme
Regarding antibacterial agents, all the following are true EXCEPT:
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0%
Aminoglycosides act on 305 ribosomal subunit
8%
Quinolones inhibit DNA gyrase
92%
Cephalosporins compete with PABA
0%
Chloramphenicol acts on the 505 ribosomal subunit
The mechanism of action of quinolones is:
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0%
Inhibition of the dindrofolate reductase
8%
Inhibition of DNA-dependent RNA polymerase
0%
Inhibition of protein synthesis by binding to the 505 ribosomal subunit
92%
Inhibition of the DNA gyrase
Guidelines for choice of an antimicrobial agents include the following EXCEPT:
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10%
Choose bactericidal rather than bacteriostatic drugs
80%
Choose broad spectrum rather than narrow spectrum antibiotics
0%
Identify the nature of infection, whether bacterial, viral or fungal
10%
Select an antibiotic that is able to penetrate to the site of infection
Regarding broad-spectrum drugs, all the following are true EXCEPT:
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0%
Often used when the pathogen has not yet identified
0%
Can also kill or inhibit the patient's normal flora and cause superinfection
9%
Likely to induce resistance to antibiotics faster than narrow spectrum drugs
91%
Can only kill Gram positive bacteria
The following are mechanisms of acquired resistance EXCEPT:
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0%
Decreasing the influx of the antibiotic
9%
Modification of the receptor (target) site
9%
Target elimination by developing new metabolic pathways
82%
Absence of cell wall in Mycoplasma
A mutation in DNA gyrase is likely to result in resistance to
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6%
Amphotericin B
88%
Quinolones
0%
Rifampicin
6%
Cephalosporins
Antibiotic disc diffusion method:
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18%
Is done test allergic reaction of the patient to the antibiotic used
0%
Can accurately determine MIC of the antibiotic
73%
Depends on measuring the dimeter of zone of inhibition around the disc
9%
Utilizes filter paper discs impregnated with antibodies to the organism
Combined antibiotic therapy is indicated in the following conditions EXCEPT:
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0%
Mixed infections
86%
Viral meningitis
7%
Sepsis in immunocompromised patient
7%
Febrile neutropenia
All are possible indications of combined antibiotic therapy EXCEPT
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13%
Febrile neutropenia
67%
To achieve antagonistic effect
0%
Mixed infection
20%
Delaying the emergence of drug resistance mutants
Complications of antibiotics include the following EXCEPT:
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9%
Hypersensitivity
27%
Superinfection
64%
Selective toxicity
0%
Emergence of resistant mutants
The following are complications of antibiotics EXCEPT:
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0%
Toxicity
82%
Immunodeficiency
9%
Drug resistance
9%
Allergy
0%
Superinfection
Opportunistic pathogens:
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56%
Many of them are originally commensals
38%
Can cause disease in immunocompetent individuals
0%
Live freely in nature
6%
Are highly virulent organisms
Virulence factors include all the following EXCEPT
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0%
Capsules
83%
Ribosomes
17%
Enzymes
0%
Adherence factors
All the following are antiphagocytic factors EXCEPT
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0%
Capsule
0%
Spore
44%
M protein & protein A
56%
Coagulase
All the following concern exotoxins EXCEPT
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7%
They are highly antigenic
47%
They have non-specific action
40%
They are produced by Gram-positive and Gram-negative bacteria
7%
They are encoded by chromosomal phage or plasmid genes
Exotoxins have the following characters, EXCEPT:
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0%
They may be encoded by genes on the chromosome
9%
They can be converted to toxins
18%
They have specific action
73%
They are heat stable