St

St. Clair College

BIOLOGY 206

Chapter 13: Control of Microbial Growth

1)Which of the following is not an example of a fomite?

A.            catheter

B.            doorknob

C.            mosquitoes

D.            towels

 

 

 

 

2.            HEPA filters are required for which Biological Safety Level (BSL)?

A.            BSL 1

B.            BSL 2

C.            BSL 3

D.            D. BSL 4

 

 

 

 

3.            From a clinical perspective, aseptic technique is carried out to do which of the following?

A.            clean fomites

B.            contaminate fomites

C.            introduce contamination in living tissue D. prevent contamination in living tissue

 

 

 

 

4.            The autoclave uses which of the following mechanism(s) for sterilization?

A.            pressure

B.            temperature

C.            pressure and temperature

D.            pressure, temperature, and pH

 

 

 

 

5.            Autoclaves are designed to kill which of the following heat-resistant microbes? A. endospores

B.            prions

C.            vegetative bacterial and fungal cells

 

 

D.            viruses

 

 

 

 

6.            The decimal reduction time (D-value) is how long it takes to kill which percentage of a microbial population?

A. 10%

B. 50% C. 90% D. 100%

 

 

 

7.            Which of the following actions would be most clearly considered bacteriostatic rather than bactericidal?

A.            autoclaving bacterial cultures

B.            placing a bacterial culture in the −80 ?C freezer

C.            spraying 70% alcohol on a laboratory bench

D.            treating a mattress with ethylene oxide

 

 

 

8.            Microbial death follows which type of trend?

A.            linear

B.            logarithmic

C.            power series

D.            variable

 

 

 

9.            Which of the following are the standard conditions for an autoclave?

A.            100 ?C, 1 psi, 60 minutes

B.            121 ?C, 1 psi, 60 minutes C.  121 ?C, 15 psi, 20 minutes

D.  212 ?C, 15 psi, 10 minutes

 

 

 

10.          Which of the following is not a milkborne pathogen?

A.            Escherichia coli O157:H7

B.            Listeria monocytogenes

 

 

C.            Salmonella enterica D. Yersinia pestis

 

 

11.          For appropriate food storage in refrigerators, the temperature should be set to no higher than which of the following?

A.            5 ?C B.  7 ?C

C.  9 ?C

D.  11 ?C

 

 

 

12.          How does pascalization control microbial growth?

A.            by cross-linking proteins

B.            by damaging DNA

C.            by denaturing proteins

D.            by disrupting membrane integrity

 

 

 

13.          X-rays and gamma rays are examples of which type of radiation?

A.            beta emission radiation B. ionizing radiation

C. nonionizing radiation

D. nonpenetrating radiation

 

 

 

14.          Ultraviolet light is an example of which type of radiation?

A.            beta emission radiation

B.            ionizing radiation

C.            nonionizing radiation

D.            penetrating radiation

 

 

 

15.          To sterilize packaged intravenous tubing, which method would not be acceptable?

A.            ethylene oxide

B.            freezing

 

 

C.            ionizing radiation

D.            nonionizing radiation

 

 

 

16.          Liquid growth media that contain antibiotics should be sterilized using which method?

A.            autoclaving

B.            boiling

C.            HEPA filtration

D.            membrane filtration

 

 

 

 

17.          Which method of microbial control introduces double-strand breaks into DNA?

A.            alcohols

B.            autoclaving

C.            ionizing radiation

D.            nonionizing radiation

 

 

 

18.          Which method of microbial control does not rely on denaturing proteins and/or disrupting the integrity of the cell membrane?

A.            autoclaving B. lyophilization

C. treatment with alcohols

D. treatment with phenolics

 

 

 

19.          Phenolic compounds can be found naturally in which group of organisms?

A.            animals

B.            bacteria

C.            fungi D. plants

 

 

 

20.          Which phenolic compound has commonly been added to soap and raises concerns about selection for more antimicrobial-resistant bacteria?

A.            capsaicin

 

 

B.            carbolic acid

C.            o-phenylphenol D. triclosan

 

 

 

21.          Which best describes how heavy metals can control microbial growth? A. by binding to sulfur-containing amino acids

B.            by cross-linking proteins

C.            by introducing double-strand breaks into DNA

D.            by inserting pores in the cell membrane

 

 

 

22.          What is argyria?

A.            a buildup of silver in the body resulting in blue-gray skin

B.            a form of skin necrosis due to topical use of phenolics

C.            inadequate blood supply resulting in chest pain

D.            microorganisms growing in the blood

 

 

 

23.          Which halogen or halogen-containing compound is typically used as a form of topical antisepsis?

A.            bromine

B.            chloramine

C.            fluorine D. iodophor

 

 

 

 

24.          All but which of the following may be used to disinfect water to make it potable?

A.            bleach

B.            chloramine

C.            fluoride

D.            sodium dichloroisocyanurate

 

 

 

 

25.          Contact lens cleaners commonly use which type of chemical agent to control microbial growth?

 

 

A.            alkylating agents B. peroxygen

C. quats

D. supercritical fluid

 

 

 

26.          Which of the following is not an alkylating agent? A. chlorhexidine

B.            ethylene oxide

C.            formalin

D.            o-phenylphenol

 

 

 

27.          Many chemical preservatives, such as potassium sorbate, preserve food products in which of the following ways?

A.            by altering the pH

B.            by binding to pathogens

C.            by changing the osmolarity

D.            by drying foods

 

 

 

28.          Nisin is an antimicrobial peptide produced by which bacterium?

A.            Lactobacillus acidophilus B. Lactococcus lactis

C. Listeria monocytogenes

D. Streptomyces natalensis

 

 

 

 

29.          Examine the disk-diffusion assay shown below. Which antimicrobial agent is the least effective?

 

 

 

A.            A

B.            B

C.            C D. D

 

 

 

30.          Which of the following is used to determine if a solution of disinfectant actively used in the clinical setting is contaminated?

A.            the disk-diffusion method B. the in-use test

C. the phenol coefficient test

D. the use-dilution test

 

 

 

True/False

 

31.          Commercial sterilization kills all microbes.

 

 

 

32.          Pasteurized foods cannot spoil.

 

 

 

33.          Autoclaves use moist heat to sterilize materials.

 

 

 

 

 

34.          X-rays and gamma rays are examples of ionizing radiation and cause the formation of thymine dimers.

 

 

 

35.          Mercurycompoundsmaybedissolvedinalcoholandusedastinctures.

 

 

 

36.          HEPA filters are able to filter many airborne virions.

 

 

 

37.          Quats are not effective against endospores and prions.

 

 

 

38.          Quats are anionic compounds.

 

 

 

39.          Soaps with no added ingredients are bactericidal.

 

 

 

40.          Sonication causes cavitation in cells.

 

 

 

 

Matching

 

41.          Match the medical instrument to its proper classification.

Note than an answer may be used more than once.

A.            catheter               i. critical

B.            colonoscope      ii. semicritical

C.            duodenoscope iii. noncritical

D.            sonogram probe

E.            sphygmomanometer (blood pressure cuff)

 

 

 

42.          Match the microbial growth control term with its correct definition.

A.            antisepsis            i. a technique used to prevent contamination to maintain sterility

B.            asepsis ii. a chemical process used to control microbial growth on body

surfaces

C.            disinfection        iii. a process that kills nonspore-forming pathogenic pathogens

D.            pasteurization   iv. lowering microbial load to public health standards

E.            sanitization         v. a chemical process used to control microbial growth on

inanimate objects

 

 

 

43.          Match the agent to its mechanism of action.

A.            alcohols                i. physically remove a microbe from a surface

B.            gamma rays        ii. damage DNA molecules

C.            heavy metals     iii. bind to sulfur-containing amino acids to inhibit enzyme activity

D.            soaps    iv. denature proteins and disrupt membrane integrity

 

 

 

44.          Match the agent to the mechanism of action.

A.            alkylating agent i. affect proteins and nucleic acids.

B.            nitric acid             ii. inhibit catalases and peroxidases

C.            quat       iii. may disrupt ferredoxin in the electron transport chain

D.            sorbic acid           iv. disrupt membrane integrity

 

 

 

 

 

Fill in the Blank

 

45.          The complete removal of vegetative cells, endospores, and viruses is known as .

 

 

 

46.          Traditional pasteurization kills pathogens and reduces the number of     while maintaining food quality.

 

 

 

 

47.          A microbiology laboratory that works with many indigenous environmental samples would be classified as a Biological Safety Lab (BSL)            .

 

 

48.                         is the appropriate method to pasteurize milk for areas where the milk cannot be refrigerated.

 

 

 

49.          Food items are irradiated using radiation.

 

 

 

50.          Prior to the use of antibiotics, newborns were routinely treated with     upon birth as protection against bacterial infection they may have acquired during passage through the birth canal.

 

 

 

 

 

51.          Recently, the heavy metal           has been used in designing pots for water storage to reduce diarrheal diseases.

 

 

 

 

52.                         is a gaseous alkylating agent used to sterilize objects, like bed mattresses, that cannot be autoclaved.

 

 

 

53.          Some bacteria and other organisms produce the enzyme             , which catalyzes the

 

reaction H2O2

 

? H2O + O2 .

 

 

 

 

54.          A recently developed method of antisepsis that can be used on skin before transplantation is

                .

 

 

 

Short Answer

 

55.          What is the difference between a disinfectant and an antiseptic?

 

 

 

56.          Which heat method (dry or moist) is more effective? Why?

 

 

 

57.          Name two quality-control methods/indicators used to determine if something has been autoclaved properly.

 

 

 

 

 

 

58.          Is desiccation a “-cidal” mechanism and what effect does it have on microbes?

 

 

 

59.          Why is it rare to hear about foodborne disease outbreaks from the consumption of candy bars?

 

 

 

60.          An experiment is conducted to see how many bacteria remain in a culture at different times and temperatures. The data are shown below.

(a)          What is the lowest temperature that represents the thermal death point?

(b)          What is the thermal death time at 67 ?C?

 

 

 

 

 

 

 

61.          How does nonionizing radiation cause mutations in DNA?

 

 

 

 

62.          What is the mode of action for iodine?

 

 

 

63.          What is the mode of action for alcohols?

 

 

 

64.          Name two chemical food preservatives that are naturally produced by microorganisms.

 

 

 

 

65.          Name one benefit of using quats.

 

 

 

Questions 66 and 67 are based on the following experiment:

Different disinfectants are soaked on sterile pads that are then placed on a lawn of bacteria. The photo below shows the results after 24 hours of incubation.

 

 

 

66.          What assay is being shown here?

 

 

 

 

67.          Which antimicrobial agent (A through F) is the most effective against the bacteria that were plated?

 

 

 

 

 

Questions 68 and 69 are based on the following experiment:

You wish to test the efficacy of a disinfectant that has been used to clean hospital rooms. The diagram below shows the experimental setup and the results.

 

 

68.          What assay is being shown here?

 

 

 

 

69.          What conclusion can you draw from the results of this experiment?

 

 

 

 

 

 

Brief Essay

Essay Question Rubric

RATING                Failing   Below

Average               Competent         Advanced

Criteria for evaluati on   Answer does not provide an argument. Answer contains inaccuracies. Writing is poor and contains numerous grammatical mistakes and misspellings.         Answer fails to provide examples to support an argument.

Writing is poor and grammatical errors are common.

Answer is somewhat incoherent.             Answer provides an argument with one or two examples that support it.

Writing is acceptable for the college level but may contain one or two grammatical mistakes or misspellings.                Answer clearly provides an argument with two or more excellent examples that support it; student makes the argument clearly and eloquently.

Answer is well organized and free of grammatical errors and

misspellings.

POINT

VALUE  0              1              2              3

Assume rating/grading scale for the question ranges from 0 to 3 points.

 

70.          A simple example of controlling microbial growth is based on how we handle our food products. Name three food preparation methods that counter microbial growth. Be sure to discuss the mode of action for each method.

 

 

 

 

 

 

71.          A company has hired you and your laboratory to test the efficacy of a new alkylating agent, “Substance X.” You prepare a culture of endospores and add Substance X. Every 5 minutes, you plate the endospores to see if they are still viable. The data from this experiment are shown below.

 

Time (minutes)

 

Number of viable endospores

 

0              50,000

5              25,500

10           5000

15           3000

20           500

25           400

30           50

35           20

40           5

 

A.            What is the mode of action for Substance X?

B.            State the independent and dependent variables of this experiment.

C.            Prepare a graph of these data using a logarithmic scale for the y-axis and a linear sale for the x-axis.

D.            What is the approximate decimal reduction time (D-value) of Substance X against the endospores used?

E.            Would you classify Substance X as a high-, intermediate- or low-level germicide? Why?

 

 

72.          Explain how hyperbaric oxygen therapy works. What types of bacterial infections can be treated with hyperbaric oxygen?

 

 

 

73.          Name two chemical preservatives and state their modes of action. Be sure to indicate whether they target bacteria and/or fungi.