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Control of microorganisms Flashcards

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Biology 101 flashcards
1
Q

The killing or removal of all viable organisms including endospores.

A

Sterilization

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2
Q

Effectively limiting microbial growth.

A

Inhibition

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3
Q

The treatment of an object to make it safe to handle.

A

Decontamination

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4
Q

Directly targets the removal of all pathogens, not necessarily all microorganisms.

A

Disinfection

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5
Q

What are the physical methods used for antimicrobial control? (3)

A
  • heat
  • radiation
  • filtration
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6
Q

What are the chemical methods used on EXTERNAL SURFACES for antimicrobial control? (3)

A
  • sterilants
  • disinfectants
  • antiseptics
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7
Q

What are the chemical methods used INTERNALLY for antimicrobial control? (3)

A
  • antibiotics
  • antivirals
  • antifungals
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8
Q

How do we call the chemical methods used for antimicrobial control?

A

Antimicrobials

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9
Q

What is the most common physical method used for controlling microbial growth?

A

Heat

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10
Q

High temperatures _____ macromolecules.

A

denature

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11
Q

What do we call the amount of time required to reduce viability tenfold?

A

Decimal reduction time (D) (100, 10, 1, 0.1)

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12
Q

What is the relationship between the decimal reduction time and temperature?

A

they are inversely correlated: as heat increases, he time required to achieve desired population decreases (D decreases)

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13
Q

The decimal reduction time necessary to kill a defined ______ is ______ of the the initial cell ______.

A

fraction; independent; concentration.

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14
Q

Time needed to kill all cells at a given temperature.

A

Thermal death time

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15
Q

Thermal death time is ________________ of microorganisms tested. Therefore, you need to ______ the starting number of cells to be able to compare the sensitivity of different microorganisms.

A

dependent on the population size; standardize

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16
Q

What is the difference between endospores and vegetative cells regarding thermal resistance?

A

Endospores survive heat that would rapidly kill vegetative cells: a higher temperature is needed to kill endospores.

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17
Q

What is the time required to reduce viable endospores by 1D (90% dead)?

A

5min

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18
Q

Sealed device that uses steam under pressure.

A

Autoclave

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19
Q

Functions of autoclave: (4)

A
  • allows temperature of water to get above 100 degrees without boiling
  • at 15 psi, steam reaches 121 degrees -> sterilization is achieved in 10-15min
  • object sterilized reaches this temperature, not suitable for heat-sensitive object/liquid
  • not the pressure that kills the microorganisms but the high temperature
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20
Q

Sterilization time:

A

when the temperature of autoclave and object being sterilized are equal (big objects might not be fully sterilized)

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21
Q

Autoclave time:

A

form the moment the pressure begins until the end of sterilization time

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22
Q

Process of using precisely controlled heat to reduce the microbial-load in heat sensitive liquids

A

Pasteurization (physical method)

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23
Q

pasteurization does not kill all organisms, it is not a method of ______.

A

sterilization

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24
Q

Reducing microbial load increases _____.

A

shelf-life of product

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25
Q

Pasteurization reduces significantly the population of many pathogens: (5)

A
  • Listeria monocytogenes
  • salmonella enterica
  • campylobacter
  • E. coli O157:H7
  • mycobacterium
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26
Q

Parameters for flash pasteurization:

A

72 degrees for 15s

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27
Q

Parameters for bulk pasteurization:

A

65 degrees for 30min

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28
Q

What are the effects of bulk pasteurization?

A

there is more protein denaturation therefore it is more used for yoghurt and ice cream production

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29
Q

Radiations include: (4) and reduce _____

A
  • UV
  • X-Rays
  • electrons
  • gamma rays
    and reduce microbial growth
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30
Q

UV has sufficient energy to cause modifications and breaks in ___, which inhibit ____, ____ and cause _____.

A

DNA; replication, transcription; death

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31
Q

Properties of UV: (3)

A
  • useful for decontamination of surfaces
  • cannot penetrate solid, opaque or light-absorbing surfaces
  • useful for disinfection of drinking water and air
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32
Q

Sources of radiation: (3)

A
  • X-rays
  • radioisotopes (emits gamma rays: highest radiation)
  • cathode ray tubes (electrons)
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33
Q

radiation is used for ______ in the medical field and food industry.

A

sterilization

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34
Q

Electromagnetic radiation that produces ions and other reactive molecules.

A

Ionizing radiation

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35
Q

What does an ionizing radiation do?

A

Generates electrons and hydroxyl radicals that cause damage to DNA and proteins

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36
Q

Concerning ionizing radiations, the amount of energy required to reduce viability tenfold is _____ to D value.

A

analogous

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37
Q

Spores are the microorganisms that withstand the ______ ionizing radiation.

A

highest

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38
Q

Why is filtration preferred on sensitive liquids and gases?

A

it avoids the use of heat

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39
Q

How does filtration work?

A

the pores of filter are small enough to prevent organisms to pass through but big enough to allow gas and liquid to pass through.

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40
Q

What are the two types of filters used for filter sterilization?

A

Depth filters and membrane filters

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41
Q

About depth filter: (structure, utilisation)

A
  • made up of fibrous sheet or mat made from an array of finer (paper or glass)
  • used to sterilize liquid and air
  • HEPA filters
42
Q

About membrane filters:

A
  • function more like a sieve
  • example: nucleation tract (nucleopore) filter
  • filtration speed can be increased by syringe, pump, vacuum
43
Q

What are the three classifications of antimicrobial agents and what happens?

A
  • bacteriostatic: inhibit growth of microorganisms (total cell count and viable cell count remain equal/stable)
  • bacteriocidal: kill microorganism (total cell count remains stable and viable cell count decreases)
  • bacteriolytic: kill microorganism by inducing lysis (total cell count and viable cell count both decrease)
44
Q

The smallest amount of an agent needed to inhibit growth of a microorganism.

A

minimum inhibition concentration (MIC)

varies with pH, temperature, organism used

45
Q

Lowest concentration of an agent that kills a test ORGANISM.

A

Minimum lethal concentration (MLC)

46
Q

Lowest concentration of an agent that kills a test BACTERIUM.

A

Minimum bacteriocidal concentration (MBC)

47
Q

How do you determine MBC?

A

Take sample from the transparent tubes and plate them on agar plates and see if any organisms grow, the one with no growth is MBC

48
Q

What is the purpose of disc diffusion assay?

A

Measures antimicrobial activity:

  • Antimicrobial agent is added on filter paper
  • zone of inhibition will be created around this disc if organism is sensitive to antimicrobial agent -> no growth
  • perimeter of this zone of inhibition is the MIC
49
Q

Why are antimicrobial compounds used?

A

they prevent spreading of a pathogen in the environment, prevent contamination of the host and cure superficial bacterial infections.

50
Q

What are the two categories of antimicrobial agents?

A
  • products used to control microorganisms in industrial and commercial applications (fuel tanks, cooling towers)
  • products used to prevent growth of human pathogens in inanimate environments and on external body surfaces (sterilants, disinfectants, sanitizers and antiseptics)
51
Q

Cold sterilization

A

destroy all forms of microorganisms as well as endospores -> sterilants

52
Q

What are the chemical antimicrobial agents for external use that are applied to non living objects or surfaces (toxic to humans/animals) and that don’t kill endospores?

A

disinfectants/sanitizers

53
Q

What are the chemical antimicrobial agents for external use that are applied on surfaces of living tissues or skin and that don’t kill endospores?

A

antiseptics

54
Q

Example of antimicrobial drugs (3) that are applied inside/outside of human body? (don’t kill endospores)

A
  • antifungals
  • antivirals
  • antibiotics
55
Q

Phenol/phenolics (use/notes)

A
  • disinfectants, antiseptics

- disrupt cytoplasmic membrane, protein denaturant (high [])

56
Q

Alcohols (use/notes)

A
  • disinfectants, antiseptics

- lipid solvent and protein denaturants

57
Q

halogens(use/notes)

A
  • disinfectants, antiseptics, sterilants
  • Chlorine (Sterilant/disinfectant): oxidizing agent ex: sodium hypochlorite
  • Iodine (antiseptic): iodinate tyrosine residues in protein, oxidizing agent
58
Q

Heavy metals (use/notes)

A
  • disinfectant

- modify proteins, interact with RNA, DNA… several different mechanisms. CuSO4, algaecide

59
Q

Quaternary ammonium (use/notes)

A
  • disinfectant/antiseptic

- interact with phospholipids of cytoplasmic membrane

60
Q

Alkylating agents (use/notes)

A
  • disinfectant, sterilant

- formaldehyde, glutaraldehyde. very toxic

61
Q

How do you classify antimicrobial drugs? (3)

A
  • molecular structure
  • mechanism of action
  • spectrum of antimicrobial activity
62
Q

Antimicrobial drugs can either be ______ or ______. They usually have a ____________

A

bacteriostatic; bactericidal; specific target

63
Q

A good antimicrobial drug has: (5)

A
  • NO sever side effects, must be far more toxic for microorganism than mammalian cell
  • low risk/benefit ratio
  • broad spectrum of activity to facilitate rapid medical intervention
  • appropriate bioavailability and pharmacokinetics (must reach site of infection)
  • low cost to develop and manufacture
64
Q

What are the possible targets? (9)

A
  • DNA-directed RNA polymerase
  • protein synthesis (50S or 30S inhibitors)
  • protein synthesis (mRNA)
  • lipid biosynthesis
  • RNA elongation
  • DNA gyrase
  • cell wall synthesis
  • folic acid metabolism
  • cytoplasmic membrane structure and function
65
Q

No antibiotics can clear _____ and ____ at the same time -> very specific

A

bacteria and viruses

66
Q

ability to inhibit or kill a pathogen without affecting the host.

A

Selective toxicity

67
Q

Who studied selective toxicity?

A

Paul Ehrlich in early 1900s

68
Q

What was one of the first antimicrobial drugs? (used to treat syphilis)

A

Salvarsan

69
Q

_________ are structurally similar to growth factors but do not function in the cell. they are similar to vitamins, AA and other compounds.

A

Growth factor analogs

70
Q

Example of and analogue of p-aminobenzoic acid?and its target? and its group?

A

SULFANILAMIDE
Group: sulpha drugs (discovered by Gerhard Domagk in 1930s)
Target: inhibits folic acid synthesis
-> bacteriostatic

71
Q

____ is a growth factor analog effective only against Mycobacterium. It interferes with synthesis of ______

A

Isoniazid; mycolic acid

72
Q

_______ are formed by addition of bromine or fluorine. Stop DNA replication

A

nucleic acid base analogs

73
Q

_______ are antibacterial compounds that interfere with DNA gyrase (control DNA supercoiling)

A

Quinolones

74
Q

_____ are antimicrobial agents _________ by a variety of bacteria and fungi to inhibit or kill other microorganisms.

A

Antibiotics; naturally produced

75
Q

What are semisynthetic antibiotics?

A

antibiotics that are modified to enhance their efficacy

76
Q

Gram + and gram - bacteria vary in their _____ to antibiotics. The cell wall is a major factor.

A

sensitivity

77
Q

What is the most important group of antibiotics? and what does it include? (3)

A 
Beta-Lactams
it includes:
- penicillins
- cephalosporins
- cephamycins
78
Q

About Penicillins:

  • who discovered it
  • where it comes from
  • what is it effective against
  • function
A
  • beta-lactam antibiotic
  • discovered by Alexander Fleming in 1928
  • isolated from Penicillum chrysogenum (mold)
  • Primarily effective against Gram + bacteria, some synthetic ae effective against gram -
  • inhibit cell wall synthesis
79
Q

About Cephalosporins:

A
  • beta-lactam antibiotic
  • produced by fungus Cephalosporium
  • same mode of action as penicillins
  • used to treat gonorrhea
80
Q

What is a penicillin-binding protein?

A

Transpeptidase (TPase)

81
Q

Beta-lactams can be _____ or _____ depending on species, growth, etc. They can also be _______ in isotonic solutions.

A

bactericidal; bacteriolytic; bacteriostatic

82
Q

How does the transpeptidase work?

A

it covalently binds to beta-lactam ring, breaking the ring -> antibiotic can’t work

83
Q

Bacteria also produce the antibiotics that are effective against them. True or False?

A

True

84
Q

What are 3 types if aminoglycosides? and what are their function?

A
  • kanamycin
  • neomycin
  • STREPTOMYCIN
  • > they are bactericidal and they target 30S ribosomal subunits which cause misreading of mRNA
85
Q

What are chloroamphenicol?

A
  • they bind to 23S rNA causing the inhibition of peptide elongation
  • they are bacteriostatic
86
Q

What are macrolides?

A
  • broad spectrum of antibiotics that target the 50S subunit of ribosome, block protein synthesis
  • bacteriostatic
87
Q

What are tetracyclines?

A
  • broad spectrum, bacteriostatic

- inhibit 30S ribosomal subunit, block protein synthesis

88
Q

What are 4 antibiotics from prokaryotes?

A
  • tetracyclines
  • macrolides
  • chloroamphinicol
  • aminoglycosides
89
Q

the acquired ability of a microorganism to resist the effects of a chemotherapeutic agent to which it is normally sensitive.

A

Antimicrobial drug resistance

90
Q

How does a microorganism become resistant to some antibiotics? (antibiotic resistance mechanism) (4)

A
  • destruction or modification of the antibiotic
  • modification of the target site
  • modification of the uptake mechanism
  • efflux pump: reduce intracellular concentration
91
Q

Antibiotic producers are tolerant because: (3)

A
  • lack target sites (no peptidoglycan)
  • modify target sites
  • lack of uptake mechanism
92
Q

Acquisition of a new ___ that provide the cells with a new function like _____

A

gene; antimicrobial resistance

93
Q

Where are the drug-resistant genes located on bacteria?

A

R plasmid

94
Q

What are the effects of the use of antibiotics in medicine, veterinary medicine, and agriculture on R plasmids?

A

it selects for the spread of R plasmids

95
Q

R plasmids can’t be transferred between bacteria of the same species or related species. True or False?

A

False

96
Q

How can resistance to antimicrobial drugs be minimized?

A

by using antibiotics correctly and only when needed -> reduce selection

97
Q

Most antiviral drugs also target _____, resulting in _____

A

host structures; toxicity

98
Q

Most used antiviral that blocks reverse transcriptase and production of viral DNA.

A

nuceloside analogs

99
Q

_____ inhibit the processing of large viral proteins into individual components and ______ prevent viruses from successfully fusing with the host cell.

A

Protease inhibitors; fusion inhibitors

100
Q

Antibiotics are effective against viruses. True or False?

A

False

101
Q

Why do fungi pose problems for chemotherapy?

A

because they are eukaryotes

102
Q

what does Fluconazole do?

A

a drug that targets ergosterol synthesis, a unique metabolic process the isn’t found in mammals

Microbiology (6 decks)

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