# Chapter 11 Exercises

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## Review Questions for Chapter 10

### Multiple Choice

1) Which of the following types of medical items requires sterilization?

1. needles
2. bed linens
4. blood pressure cuffs

2) Which of the following is suitable for use on tissues for microbial control to prevent infection?

1. disinfectant
2. antiseptic
3. sterilant
4. water

3) Which biosafety level is appropriate for research with microbes or infectious agents that pose moderate risk to laboratory workers and the community, and are typically indigenous?

1. BSL-1
2. BSL-2
3. BSL-3
4. BSL-4

4) Which of the following best describes a microbial control protocol that inhibits the growth of molds and yeast?

1. bacteriostatic
2. fungicidal
3. bactericidal
4. fungistatic

5) The decimal reduction time refers to the amount of time it takes to which of the following?

1. reduce a microbial population by 10%
2. reduce a microbial population by 0.1%
3. reduce a microbial population by 90%
4. completely eliminate a microbial population

6) Which of the following methods brings about cell lysis due to cavitation induced by rapid localized pressure changes?

1. microwaving
4. sonication

7) Which of the following terms is used to describe the time required to kill all of the microbes within a sample at a given temperature?

1. D-value
2. thermal death point
3. thermal death time
4. decimal reduction time

8) Which of the following microbial control methods does not actually kill microbes or inhibit their growth but instead removes them physically from samples?

1. filtration
2. desiccation
3. lyophilization

9) Which of the following refers to a disinfecting chemical dissolved in alcohol?

1. iodophor
2. tincture
3. phenolic
4. peroxygen

10) Which of the following peroxygens is widely used as a household disinfectant, is inexpensive, and breaks down into water and oxygen gas?

1. hydrogen peroxide
2. peracetic acid
3. benzoyl peroxide
4. ozone

11) Which of the following chemical food preservatives is used in the wine industry but may cause asthmatic reactions in some individuals?

1. nitrites
2. sulfites
3. propionic acid
4. benzoic acid

12) Bleach is an example of which group of chemicals used for disinfection?

1. heavy metals
2. halogens
3. quats
4. bisbiguanides

13) Which chemical disinfectant works by methylating enzymes and nucleic acids and is known for being toxic and carcinogenic?

1. sorbic acid
2. triclosan
3. formaldehyde
4. hexaclorophene

14) Which type of test is used to determine whether disinfectant solutions actively used in a clinical setting are being used correctly?

1. disk-diffusion assay
2. phenol coefficient test
3. in-use test
4. use-dilution test

15) The effectiveness of chemical disinfectants has historically been compared to that of which of the following?

1. phenol
2. ethyl alcohol
3. bleach
4. formaldehyde

16) Which of the following refers to a germicide that can kill vegetative cells and certain enveloped viruses but not endospores?

1. high-level germicide
2. intermediate-level germicide
3. low-level germicide
4. sterilant

17) A scientist discovers that a soil bacterium he has been studying produces an antimicrobial that kills gram-negative bacteria. She isolates and purifies the antimicrobial compound, then chemically converts a chemical side chain to a hydroxyl group. When she tests the antimicrobial properties of this new version, she finds that this antimicrobial drug can now also kill gram-positive bacteria. The new antimicrobial drug with broad-spectrum activity is considered to be which of the following?

1. resistant
2. semisynthetic
3. synthetic
4. natural

18) Which of the following antimicrobial drugs is synthetic?

1. sulfanilamide
2. penicillin
3. actinomycin
4. neomycin

19) Which of the following combinations would most likely contribute to the development of a superinfection?

1. long-term use of narrow-spectrum antimicrobials
2. long-term use of broad-spectrum antimicrobials
3. short-term use of narrow-spectrum antimicrobials
4. short-term use of broad-spectrum antimicrobials

20) Which of the following routes of administration would be appropriate and convenient for home administration of an antimicrobial to treat a systemic infection?

1. oral
2. intravenous
3. topical
4. parenteral

21) Which clinical situation would be appropriate for treatment with a narrow-spectrum antimicrobial drug?

1. treatment of a polymicrobic mixed infection in the intestine
2. prophylaxis against infection after a surgical procedure
3. treatment of strep throat caused by culture identified Streptococcus pyogenes
4. empiric therapy of pneumonia while waiting for culture results

22) Which of the following terms refers to the ability of an antimicrobial drug to harm the target microbe without harming the host?

1. mode of action
2. therapeutic level
3. spectrum of activity
4. selective toxicity

23) Which of the following is not a type of β-lactam antimicrobial?

1. penicillins
2. glycopeptides
3. cephalosporins
4. monobactams

24) Which of the following does not bind to the 50S ribosomal subunit?

1. tetracyclines
2. lincosamides
3. macrolides
4. chloramphenicol

25) Which of the following antimicrobials inhibits the activity of DNA gyrase?

1. polymyxin B
2. clindamycin
3. nalidixic acid
4. rifampin

26) Which of the following is not an appropriate target for antifungal drugs?

1. ergosterol
2. chitin
3. cholesterol
4. β(1→3) glucan

27) Which of the following drug classes specifically inhibits neuronal transmission in helminths?

1. quinolines
2. avermectins
4. imidazoles

28) Which of the following is a nucleoside analog commonly used as a reverse transcriptase inhibitor in the treatment of HIV?

1. acyclovir
2. ribavirin
4. azidothymidine

29) Which of the following is an antimalarial drug that is thought to increase ROS levels in target cells?

1. artemisinin
2. amphotericin b
3. praziquantel
4. pleconaril

30) Which of the following resistance mechanisms describes the function of β-lactamase?

1. efflux pump
2. target mimicry
3. drug inactivation
4. target overproduction

31) Which of the following resistance mechanisms is commonly effective against a wide range of antimicrobials in multiple classes?

1. efflux pump
2. target mimicry
3. target modification
4. target overproduction

32) Which of the following resistance mechanisms is the most nonspecific to a particular class of antimicrobials?

1. drug modification
2. target mimicry
3. target modification
4. efflux pump

33) Which of the following types of drug-resistant bacteria do not typically persist in individuals as a member of their intestinal microbiota?

1. MRSA
2. VRE
3. CRE
4. ESBL-producing bacteria

34) In the Kirby-Bauer disk diffusion test, the _______ of the zone of inhibition is measured and used for interpretation.

1. diameter
2. microbial population
3. circumference
4. depth

35) Which of the following techniques cannot be used to determine the minimum inhibitory concentration of an antimicrobial drug against a particular microbe?

1. Etest
2. microbroth dilution test
3. Kirby-Bauer disk diffusion test
4. macrobroth dilution test

36) The utility of an antibiogram is that it shows antimicrobial susceptibility trends

1. over a large geographic area.
2. for an individual patient.
3. in research laboratory strains.
4. in a localized population.

37) Which of the following has yielded compounds with the most antimicrobial activity?

1. water
2. air
3. volcanoes
4. soil

### Fill-in-the-Blanks

38) A medical item that comes into contact with intact skin and does not penetrate sterile tissues or come into contact with mucous membranes is called a(n) ________ item.

39) The goal of ________ ________ protocols is to rid canned produce of Clostridium botulinum endospores.

40) In an autoclave, the application of pressure to ________ is increased to allow the steam to achieve temperatures above the boiling point of water.

41) Doorknobs and other surfaces in clinical settings are often coated with ________, ________, or ________ to prevent the transmission of microbes.

42) If a chemical disinfectant is more effective than phenol, then its phenol coefficient would be ________ than 1.0.

43) If used for extended periods of time, ________ germicides may lead to sterility.

44) In the disk-diffusion assay, a large zone of inhibition around a disk to which a chemical disinfectant has been applied indicates ________ of the test microbe to the chemical disinfectant.

45) The group of soil bacteria known for their ability to produce a wide variety of antimicrobials is called the ________.

46) The bacterium known for causing pseudomembranous colitis, a potentially deadly superinfection, is ________.

47) Selective toxicity antimicrobials are easier to develop against bacteria because they are ________ cells, whereas human cells are eukaryotic.

48) Antiviral drugs, like Tamiflu and Relenza, that are effective against the influenza virus by preventing viral escape from host cells are called ________.

49) Staphylococcus aureus, including MRSA strains, may commonly be carried as a normal member of the ________ microbiota in some people.

50) The method that can determine the MICs of multiple antimicrobial drugs against a microbial strain using a single agar plate is called the ________.

51) What are some characteristics of microbes and infectious agents that would require handling in a BSL-3 laboratory?

52) What is the purpose of degerming? Does it completely eliminate microbes?

53) What are some factors that alter the effectiveness of a disinfectant?

54) What is the advantage of HTST pasteurization compared with sterilization? What is an advantage of UHT treatment?

55) How does the addition of salt or sugar help preserve food?

56) Which is more effective at killing microbes: autoclaving or freezing? Explain.

57) Which solution of ethyl alcohol is more effective at inhibiting microbial growth: a 70% solution or a 100% solution? Why?

58) When might a gas treatment be used to control microbial growth instead of autoclaving? What are some examples?

59) What is the advantage of using an iodophor rather than iodine or an iodine tincture?

60) Why were chemical disinfectants once commonly compared with phenol?

61) Why is length of exposure to a chemical disinfectant important for its activity?

62) Where do antimicrobials come from naturally? Why?

63) Why was Salvarsan considered to be a “magic bullet” for the treatment of syphilis?

64) When prescribing antibiotics, what aspects of the patient’s health history should the clinician ask about and why?

65) When is using a broad-spectrum antimicrobial drug warranted?

66) If human cells and bacterial cells perform transcription, how are the rifamycins specific for bacterial infections?

67) What bacterial structural target would make an antibacterial drug selective for gram-negative bacteria? Provide one example of an antimicrobial compound that targets this structure.

68) How does the biology of HIV necessitate the need to treat HIV infections with multiple drugs?

69) Niclosamide is insoluble and thus is not readily absorbed from the stomach into the bloodstream. How does the insolubility of niclosamide aid its effectiveness as a treatment for tapeworm infection?

70) Why does the length of time of antimicrobial treatment for tuberculosis contribute to the rise of resistant strains?

71) What is the difference between multidrug resistance and cross-resistance?

72) How is the information from a Kirby-Bauer disk diffusion test used for the recommendation of the clinical use of an antimicrobial drug?

73) What is the difference between MIC and MBC?

### Critical Thinking

74) When plotting microbial death curves, how might they look different for bactericidal versus bacteriostatic treatments?

75) What are the benefits of cleaning something to a level of cleanliness beyond what is required? What are some possible disadvantages of doing so?

76) In 2001, endospores of Bacillus anthracis, the causative agent of anthrax, were sent to government officials and news agencies via the mail. In response, the US Postal Service began to irradiate mail with UV light. Was this an effective strategy? Why or why not?

77) Do you think naturally produced antimicrobial products like nisin and natamycin should replace sorbic acid for food preservation? Why or why not?

78) Why is the use of skin disinfecting compounds required for surgical scrubbing and not for everyday handwashing?

79) What are some advantages of use-dilution and in-use tests compared with the disk-diffusion assay?

80) In nature, why do antimicrobial-producing microbes commonly also have antimicrobial resistance genes?

81) Why are yeast infections a common type of superinfection that results from long-term use of broad-spectrum antimicrobials?

82) Too often patients will stop taking antimicrobial drugs before the prescription is finished. What are factors that cause a patient to stop too soon, and what negative impacts could this have?

83) In considering the cell structure of prokaryotes compared with that of eukaryotes, propose one possible reason for side effects in humans due to treatment of bacterial infections with protein synthesis inhibitors.

84) Which of the following molecules is an example of a nucleoside analog?

85) Why can’t drugs used to treat influenza, like amantadines and neuraminidase inhibitors, be used to treat a wider variety of viral infections?

86) Can an Etest be used to find the MBC of a drug? Explain.

87) Who should be responsible for discovering and developing new antibiotics? Support your answer with reasoning.

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