Microbiology chapter 9
49. ________ and ________ can be used to prevent influenza A infections, reducing the incidence of influenza by 50 to 70% in an exposed population.
Amantadine, rimantadine
44. _______________ ________________ from Streptomyces spp. binds to the sterols in fungal membranes, disrupting membrane permeability and causing leakage of cell constituents.
Amphotericin B
3. The use of arsenic compound Salvarsan as a treatment for syphilis is credited to
B. Ehrlich.
11. Which of the following inhibits protein synthesis?
B. Erythromycin
42. Which of the following is normally treated by antifungal creams and solutions?
B. Superficial mycoses
48. Which of the following is the major reason why it has been difficult to treat viral infections with chemotherapeutic agents?
B. Viruses use the metabolic machinery of their hosts, which limits many of the potential points of attack
24. The E test is
B. a quantitative antibiotic sensitivity test that utilizes plastic strips impregnated with an antibiotic of interest.
54. The antimicrobial action of artemisinin is not well understood but this chemical appears to
B. form reactive oxygen intermediates inside Plasmodium-infected red blood cells.
31. Sulfonamides and other drugs that inhibit folic acid synthesis have a high therapeutic index because
B. humans do not synthesize folic acid but obtain it in their diets.
35. Bacitracin
B. inhibits peptidoglycan synthesis.
13. Isoniazid is a narrow-spectrum antibiotic that
B. is one of the few drugs effective against Mycobacterium tuberculosis.
29. In addition to inhibiting the transpeptidation reaction in cell wall synthesis, penicillins may also destroy bacteria by
B. stimulating proteins to form holes in the plasma membrane.
16. Chemotherapeutic agents that are artificially produced are most specifically referred to as __________.
B. synthetic drugs
26. Which of the following is not true about Kirby-Bauer disk diffusion method?
C. Bacteria used to swab plate should be at least a week old.
43. The treatment for pneumonia caused by Pneumocystis jiroveci in AIDS patients is
C. Combination of trimethoprim and sulfisoxazole
12. Which of the following is likely to have the most toxic side effects to humans?
C. Disrupters of cell membrane structure
38. Which of the following antibiotics specifically inhibits DNA synthesis?
C. Quinolones
47. Which of the following is sometimes useful against viral infections?
C. Zidovudine
4. Chemotherapeutic agents that are natural products of microorganisms are most specifically referred to as
C. antibiotics
30. Aminoglycoside antibiotics
C. bind to the 30S ribosomal subunit.
36. Vancomycin
C. inhibits the transpeptidation reaction in peptidoglycan biosynthesis.
70. The major reason why there are fewer antiprotozoan drugs than antibacterial drugs is because
C. it is much more difficult to develop selectively toxic antiprotozoan drugs since protozoan cells are eukaryotic.
18. The minimal lethal concentration (MLC) is the
C. lowest concentration of a drug that kills a particular pathogen.
32. Antibiotics that are given by injection are said to have a(n) __________ route of administration.
C. parenteral
17. The ratio of toxic dose to therapeutic dose is called the
C. therapeutic index.
20. Which of the following is a desirable general characteristic of antimicrobial drugs? A. Selective toxicity B. Broad-spectrum of activity C. Bactericidal rather than bacteriostatic D. All of the choices are correct.
D. All of the choices are correct.
23. Which of the following affects the size of the clear zone in a disk diffusion test of antimicrobial susceptibility? A. The initial concentration of the drug B. The solubility of the drug C. The diffusion rate of the drug D. All of the choices are correct.
D. All of the choices are correct.
34. Which of the following is (are) true about cephalosporins? A. They, like penicillin, inhibit bacterial cell wall synthesis. B. There are four generations of cephalosporins. C. They can be given to patients with penicillin allergies. D. All of the choices are correct.
D. All of the choices are correct.
37. Which of the following is a useful mechanism of action for an antibacterial drug? A. Inhibition of cell wall synthesis B. Inhibition of protein synthesis C. Interference with RNA and DNA synthesis D. All of the choices are correct.
D. All of the choices are correct.
58. The concentration of an antimicrobial drug that is reached in the body will depend on A. the amount of drug administered. B. the route of administration and speed of uptake. C. the rate at which the drug is cleared or eliminated from the body. D. All of the choices are correct.
D. All of the choices are correct.
65. Which of the following is (are) used by microorganisms to become resistant to a particular drug? A. Enzymatic inactivation of the drug B. Exclusion of the drug from the cell C. An alternate metabolic pathway that bypasses the drug-sensitive step D. All of the choices are correct.
D. All of the choices are correct.
27. Which of the following does not inhibit protein synthesis?
D. Penicillin
14. Consider an antibacterial drug. In which of the following cases would the action of the drug be considered primarily bacteriostatic?
D. The MLC is 10-20 times higher than the MIC.
60. Genes for drug resistance may be present
D. both on the chromosome and on plasmids
52. Drugs are used to treat malaria include
D. chloroquine and qualaquin.
15. Chemotherapeutic agents that are chemically modified natural products of microorganisms are most specifically referred to as __________.
D. semisynthetic drugs
51. The antiviral drugs currently approved for use in HIV disease include A. nucleoside reverse transcriptase inhibitors. B. nonnucleoside reverse transcriptase inhibitors. C. protease inhibitors. D. fusion inhibitors. E. All of the choices are correct.
E. All of the choices are correct.
50. All of the following are reverse transcriptase inhibitors used to treat HIV infection EXCEPT
E. acyclovir.
64. Development of drug resistance is encouraged by
E. widespread use of broad-spectrum drugs.
22. In a disk diffusion assay for drug susceptibility, a drug producing a larger clear zone is always more effective than a drug than to one producing a smaller clear zone.
FALSE
25. In the broth dilution test, the highest concentration of the antibiotic resulting in no growth after 16 to 20 hours of incubation is the MIC.
FALSE
39. Protein synthesis inhibitors have a low therapeutic index because they usually cannot discriminate between prokaryotic and eukaryotic ribosomes.
FALSE
40. Ampicillin, like penicillin, must be administered by injection because it is rapidly degraded in the stomach and cannot, therefore, be given orally.
FALSE
55. Most of the drugs used to treat protozoan infection have insignificant side effects; because protozoa are prokaryotes, the potential for drug action on host cells and tissues is less than it is when targeting bacteria.
FALSE
69. Most antiprotozoan drugs have few side effects since there are numerous cellular targets found in protozoa but not found in host cells that can be targeted with antiprotozan drugs.
FALSE
8. Agents that are static and, therefore, do not kill infecting microorganisms are not useful as chemotherapeutic agents.
FALSE
6. __________ __________ are activities of a chemotherapeutic agent that damage the host either by inhibiting the same process in the host as in the target cell or by damaging other processes.
Side effects
45. Treatment of fungal infections is more difficult than treatment of bacterial infections because the greater metabolic similarity between the fungi and their hosts limits the ability of a drug to have a selective toxicity.
TRUE
53. Metronidazole is used to treat Entamoeba infections.
TRUE
56. Bacteria in biofilms or abscesses may be replicating very slowly and are therefore resistant to chemotherapy because many agents affect pathogens only if they are actively growing and dividing.
TRUE
59. Penicillin G is frequently injected but not normally given orally because it is rapidly degraded in the stomach.
TRUE
61. One way in which organisms may exhibit resistance to a drug is the ability to pump the drug out of the cell immediately after it has entered.
TRUE
62. The effects of most antimicrobial drugs are greater if the microorganisms are actively growing.
TRUE
63. One way that the development of drug resistance in viruses has been reduced has been by the use of a cocktail of several drugs at high doses.
TRUE
66. In order for successful antibiotic therapy, the in vivo level of the antibiotic must be greater than or equal to the MIC.
TRUE
7. The minimum lethal concentration (MLC) is the lowest concentration of drug from which organisms fail to recover when removed from the drug.
TRUE
9. A drug that disrupts a microbial function not found in animal cells usually has a higher therapeutic index.
TRUE
46. A neuraminidase inhibitor called __________ is sometimes used in the treatment of people infected with influenza viruses.
Tamiflu
41. A(n) __________ is a drug that blocks the function of a metabolic pathway.
antimetabolite
21. When a chemotherapeutic agent is effective against many different pathogens, it is said to be a __________ antibiotic.
broad-spectrum
67. An antimicrobial drug that inhibits the growth of bacteria without affecting the growth or function of cells in the human host is described as being ___________ ____________.
selectively toxic
10. The drug level required for the clinical treatment of a particular infection is called the
A. therapeutic dose.
68. The aminoglycosides and tetracycline specifically target the ________________ interfering with ____________.
A. 30s ribosomal subunit; protein synthesis
1. Who is usually credited with the discovery of penicillin?
A. Fleming
5. Who is generally credited with the discovery of sulfanilamide as a chemotherapeutic agent?
A. Gerhard Domagk
2. Whose discovery of streptomycin stimulated an intense search for other antibiotics?
A. Waksman
28. The most selective antibacterial agents are those that interfere with bacterial cell wall synthesis. This is because
A. bacterial cell walls have a unique structure not found in eukaryotic host cells
57. The chemotherapeutic agent must reach levels in the body that are ________ the pathogen's MIC value if it is going to be effective.
A. greater than
19. The lowest concentration of an antibiotic that prevents growth is the
A. minimal inhibitory concentration (MIC).
33. Sulfonamides inhibit the production of folic acid and, therefore, inhibit the synthesis of __________.
A. purines and pyrimidines
