This set of Microbiology Multiple Choice Questions & Answers focuses on “Microbiological Assay of Antibiotics, Antifungal, Antiviral and Antitumour Antibiotics”.
1. Which of the following is the most accurate method for microbial assay of antibiotics?
a) Physical assay
b) Chemical assay
c) Biological assay
d) Chemical and biological assay
Explanation: Chemical-assay methods are generally more accurate and require less time than biological methods, but they are less sensitive, and caution must be used lest biologically inactive degradation products give misleading results.
2. The international unit of penicillin is defined by how much amount of International Standard?
a) 1 mg
b) 0.262 µg
c) 0.5988 µg
d) 0.5 mg
Explanation: The international unit of penicillin is the amount of activity produced under defined conditions by 0.5988 µg of the International Standard, which is a sample of pure benzyl-penicillin.
3. Zone of inhibition is observed in tube-dilution method.
Explanation: Small paper disks impregnated with known amounts of chemotherapeutic agents are placed upon the surface of an inoculated plate. So after incubation in disk-plate methods, a zone of inhibition around the disk indicates that the organism was inhibited by the drug.
4. Pigs respond dramatically to the addition of which of the following antibiotics to their diet?
Explanation: It has been suggested that pigs respond dramatically to the addition of oxytetracycline to their diet because the antibiotic inhibits the growth of Clostridium perfringens in their intestines and prevents a chronic but subclinical toxemia.
5. Which of the following antibiotic have a sparing effect on the B12 in the diet?
Explanation: Streptomycin may have a “sparing effect” on the B12 in the diet, making it available in greater quantities for utilization by the animals.
6. Antibiotics are not effective against plant pathogens.
Explanation: Some antibiotics are effective against plant pathogens and are attractive for the treatment of plant diseases. The extent of this practice is limited mainly by economic factors, i.e, the cost of the antibiotic.
7. Nystatin is produced from the strain _____________________
a) Streptomyces noursei
b) Streptomyces aureofaciens
c) Streptomyces kanamyceticus
d) Streptomyces fradiae
Explanation: Nystatin is an antifungal agent produced during fermentation by a strain of Streptomyces noursei.
8. Griseofulvin is useful in the therapy of nonsystemic fungal infections.
Explanation: Griseofluvin is used in the treatment of many superficial fungal infections of the skin and body surfaces and is also effective in the treatment of systemic mycoses.
9. Acycloguanosine is a nucleoside analog which is active against ___________________
a) Influenza A virus
b) HIV virus
c) Herpes virus
d) Influenza B virus
Explanation: Acycloguanosine is a nucleoside analog that is active against the herpes virus in animals. Its mode of action appears to be that of inhibition of nucleotide utilization.
10. Which of the following has its antiviral action attributed to the interference of protein synthesis?
Explanation: The antiviral action of interferons is attributed to interference of protein synthesis. Interferons is among the most promising chemotherapeutic agents for treating viral diseases.
11. Amantadine is very effective against influenza A virus.
Explanation: Amantadine is a low-molecular weight compound which is very effective against influenza A virus; it is not effective against influenza B. The incidence of influenza A infection is greatly reduced by the use of this drug.
12. Which of the following is effective in the control of tuberculosis in humans?
b) Nalidixic Acid
Explanation: Isonicotinic acid Hydrazide or Isoniazid has proved to be very useful in the control of tuberculosis in humans and is more effective when given alternately with streptomycin.
13. Anthramycin is which of the following type of antibiotic?
Explanation: The anthramycin group (anthramycin, sibromycin, tomaymycin and neothramycin) is an example of potent antitumor agents. Their antitumor activity is directed towards DNA structure and function.
Sanfoundry Global Education & Learning Series – Microbiology.
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