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21. Broad-spectrum antibiotics are always safer than narrow-spectrum antibiotics

ID: 52444 • Letter: 2

Question

21. Broad-spectrum antibiotics are always safer than narrow-spectrum antibiotics in clinical infections.
T or F

22. Antibiotics are produced as a group of closely related compounds and therefore purification of the active form is challenging.

T or F

23. Which of the following antibiotics you expect to encounter a higher frequency of resistant microorganisms in our community?
a. Antibiotic A that has been used for 3 years in El Paso, b. Antibiotic B that has been used for 15 years in El Paso c. Antibiotic C that was introduced last month in El Paso d. The frequency of resistant microrganism will be very similar for all of these antibiotics.

24. Polymyxin B is an antibiotic that binds to lipopolysaccharide. Classify the spectrum of this antibiotic...

a. broad, b. narrow, c. general, d. particular

25. The cell membrane in Gram negative bacteria is rich in lipopolysaccharide.

T or F

26. Select the mechanism of lateral gene flow in which the DNA is transferred by cell-to-cell contact through pili to another cell...

a. transfection, b. conjugation, c. transduction, d. transformation

27. Always hydrophilic substances enter the cell by diffusion across the cell.

T or F

28. Antiviral drugs are difficult to develop because

a.The market for antivirals is very small, b. Viral infections do not have a major impact in human health, c. A relevant selective toxicity is difficult to achieve in antiviral drugs, d. All the statements above are correct.


29. Polymyxin B is an antibiotic that binds to lipopolysaccharide and destroy the integrity of the outer membrane. What function of the outer membrane you predict will be primarily affected by polymyxin B?

a. Maintenance of the shape and rigidity of the bacteria, b. Bacterial motility, c.

Semi-permeability barrier, d. Adhesion to other microorganisms

30. Pure cultures are useful to determine antibiotic susceptibility in clinical infections.

T or F

31. Phospholipids are located in the inner leaflet of the outer membrane

T or F

32. Polymyxin B is an antibiotic that binds to lipopolysaccharide. Will the bacterial peptidoglycan limit the accessibility of polymyxin B to the lipopolysaccharide?

a. No, b. Yes, c. Yes, but only in Gram negative bacteria. d. Yes, but only in Gram positive bacteria.

33. The Gram staining is largely influence by the thickness of the...

a. pilus, b. cellular membrane, c. peptidoglycan, d. flagellum

34. Lateral gene flow is an important mechanism of evolution.

T or F

35. Lateral gene flow has low importance in the spreading of genes implicated in bacterial pathogenesis (ability of bacteria to cause diseases).

T or F

******36. What would be your prediction?

a. Bacteria are more sensitive to penicillin during the stationary phase of growth, b. Bacteria are more sensitive to penicillin during the log phase of growth, c. The sensitivity to penicillin is very similar during all the phases of the growth curve., d. .....(.missing option)

37. Amino acids located in the external surface of a channel-forming protein inserted in a biological membrane are:

a. A mixture of hydrophilic and hydrophobic, b. hydrophilic, c. hydrophobic, d. it is unpredictable

38. Lateral gene flow is implicated in the adaptation of the bacteria to the environment.

T or F.

Explanation / Answer

21. True

22. True

23. C. Antibiotic introduced in last month because old antibiotics may not be effective as newer ones. Bacteria develop the resistance towards old antibiotics.

24. d. particular

25. true

26. b. conjugation

27. true

28. C

29. a. maintenance of shape and rigidity of bacteria

30. true

31. true

32. c only in Gram negative bacteria

33. c. peptidoglycan

34. true

35. false

36. b. Bacteria are more sensitive to penicillin during the log phase of growth

37. a

38. true

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