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Microbiology > Lecture 7 - Control of Microbial Growth > Flashcards

Lecture 7 - Control of Microbial Growth Flashcards

1
Q

Asepsis

A

refers to the absence of significant contamination

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2
Q

Sepsis

A

refers to significant contamination

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3
Q

Who introduced antisepsis techniques into medical practice by having doctors wash hands with Calcium Hypochloride.

A

Ignaz Semmelweis

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4
Q

Why were so many women dying after childbirth in Semmelweis’s maternity ward?

A

The medical students were not washing their hands between doing vaginal exams on dead patients and doing vaginal exams on women in labor.

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5
Q

Known as “The Savior of the Mothers”

A

Ignaz Semmelweis

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6
Q

Phenol AKA

A

Carboxylic Acid

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7
Q

Introduced the use of phenol in surgeries

A

Joseph Lister

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8
Q

Sterilization

A

killing all forms of microbes on non-living objects

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9
Q

Antisepsis Techniques

A

killing microbes (including potential pathogens) on living tissues

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10
Q

Disinfections

A

destroying mirobes (not including endospores) on non-living surfaces

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11
Q

Using an alcohol wipe to remove microbes from a small area of skin is referred to as ______.

A

Degerming

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12
Q

Washing hands with soap is an example of _______.

A

Degerming

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13
Q

Why does soap work to remove germs?

A

soap is made of ampipathic molecules with a polar and non-polar side allowing it to bind to both the water and the oils so germs stuck in the oil can be lifted and washed away

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14
Q

nosocomial infections

A

infections aquired at a hospital or during healthcare treatment

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15
Q

What microbe is a common cause of nosocomial infections?

A

Pseudomonas aeruginosa

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16
Q

Is Pseudomonas aeruginosa Hemolytic?

A

Yes, it is beta-hemolytic and will completely destroy RBCs

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17
Q

RBC

A

Red Blood Cells

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18
Q

WBC

A

White Blood Cells

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19
Q

Is Pseudomonas aeruginosa Gram Positive or Negative?

A

Gram-Negative

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20
Q

Why is Pseudomonas aeruginosa so difficult to destroy?

A

It is magnesium in the outer membrane which aids in very strong bonds between the lipopolysaccharide molecules making it resistant to penetration by antiseptic compounds

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21
Q

Name a few things that are effective in destroying Pseudomonas

A
  • Acids
  • Glutaraldehyde
  • Silver
  • Strong Phenolic Disinfectants
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22
Q

-static / -stasis

A

stop/stand still

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23
Q

3 Main Targets of Microbial Control Agents

A
  • Plasma Membrane
  • Intracellular Proteins (i.e. enzymes)
  • Nucleic Acids (i.e. DNA/RNA)
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23
Q

-cide

A

to kill

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24
Q

3 Main Methods of Damaging Microbes

A
  • Heat
  • Chemicals
  • Radiation
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25
Q

Factors Affecting the Rate of Microbial Death

A
  • Number of Microbes
  • Presence of Organic Debris
  • pH
  • Temp
  • Nature of Suspending Medium
  • Time of Exposure
  • Characteristics of the Microbe Being Attacked
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26
Q

Desiccation

A

creating a hypertonic environment to dehydrate cells

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27
Q

Is desication effective against endospores?

A

No

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28
Q

Is desiccation effective against viruses?

A

No

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29
Q

Is desiccation effective against most bacteria?

A

Yes

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30
Q

Why are low temps effective against microbes?

A

It decreases the metabolic rate against most microbes so they cannot grow or produce toxins easily

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31
Q

Thermal Death Point

A

the lowerst temperature at which all microbes in a suspension can be killed in 10 minutes

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32
Q

Thermal Death Time

A

the minimum length of time it would take to kill all bacteria in a liquid culture at a certain temp

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33
Q

Dismal Retention Time

A

the length of time it will take to kill 90% of microbes in a suspension at a given temp

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34
Q

How long should something boil to kill most of the microbes?

A

10 minutes

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35
Q

How resistant are endospores to boiling?

A

It depends on the type of endospore, but some Hepatitis endospores can survive 30 minutes of boiling and other endospores can survive almsot a full day of boiling

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36
Q

Autoclaving

A

a true and effective sterilization method

uses moist heat at 121 C at 15 psi for 15 minutes to sterilize metal and glass

37
Q

prion

A

infectious misfolded proteins

38
Q

Can prions survive autoclaving?

A

Yes, some prions can survive autoclaving

39
Q

Pastuerization

A

uses heat to destroy pathogens and reduce the number of microbes that can spoil food

40
Q

Does pasturization change the nutritional composition of milk?

A

No

41
Q

HTST

A

High Temperature, Short Time

42
Q

HTST Pasturization AKA

A

Flash Pasturization

43
Q

UHT

A

Ultra High Temperature

44
Q

How long does it take to treat milk using HTST Pasteurization vs UHT Sterilization?

A

HTST takes 15 seconds whereas UHT takes 4 seconds

45
Q

What method of treatment has Gossner’s Milk undergone in order to be stored unrefridgerated on the shelf?

A

UHT Sterilization

46
Q

Can UHT Sterilization kill endospores?

A

Yes

47
Q

Three Methods of Dry-Heat Sterilization

A

Open Flame
Heated Incinerator
Hot Air Oven

48
Q

Which method of serilization is faster? Moist Heat or Dry Heat?

A

Moist Heat

49
Q

Two Methods Used to Sterilize Substances That Cannot Be Treated With Heat

A

Membrane Filtration
High Pressure
Radiation (ionizing or nonionizing)

50
Q

What two microbes could potentially survive membrane filtration and why?

A

Spirochaetes (may be able to wiggle their way throught holes in the filter)

Mycoplasma does not have a cell wall and may be able to distort its shape enough to fit through the holes in the filter.

51
Q

Two Types of Radiation

A

Ionizing Radiation
Nonionizing Radiation

52
Q

Ionizing Radiation

A

uses gamma rays, xrays or high-energy electron beams to penetrate cells and break apart water molecules into free radicals that can destroy DNA molecules

53
Q

Non-Ionizing Radiation

A

uses UV light to create thymine dimers in the DNA which prevents DNA replication and transcription

54
Q

Which type of radiation penetrates deeper? Ionizing or Nonionizing?

A

Ionizing

55
Q

Why are microwave ovens beneficial in killing pathogens?

A

it generates heat which can denature proteins in microbes

56
Q

What method was used to sterilize catheters and prevent UTIs in catheterized patients?

A

High-Intensity Narrow-Spectrum (HINS) Light

57
Q

Two Methods Used to Evaluate a Disinfectant

A
  • Use-Dilution Test
  • Disk-Diffusion Method
58
Q

Expalin How the Disk-Diffusion Method Works to Evaluate a Disinfectant

A

small paper disks soaked in disinfectant are placed on an agar plate covered in microbial growth then the zones of inhibition where microbes have been prevented from growing are evaluated

59
Q

Phenol works by ____.

A

Damaging Plasma Membranes

60
Q

Name 4 Halogens

A

Fluorine
Chlorine
Bromine
Iodine

61
Q

Iodine and Iodophors works as an antiseptic by

A

inhibiting protein synthesis and altering cell membranes

62
Q

Chlorine works as an antiseptic by

A

penetraiting cell walls and inhibit cellular enzymes

63
Q

What dilution of bleach is recomended?

A

1 part chloride to 4 parts water

64
Q

What percent of rubbing alcohol is most effective againt microbes?

A

70%

65
Q

Why is 100% ethanol ineffective against microbes?

A

it evaporates too quickly and doesn’t have sufficient time to destroy microbes

66
Q

How does rubbing alcohol work against microbes?

A

It denatures proteins and dissolves lipids/disrupts plasma membranes

67
Q

Oligodynamic Action

A

only a small amount is required in order to be effective

68
Q

Heavy Metals are effective against microbes by

A

denaturing proteins

69
Q

Examples of Heavy Metal Compounds Used to Combat Microbes

A

Silver Nitrate
Silver Sulfadiazene
Surfacine

70
Q

Silver Sulfadiazene is often applied topically to treat ____.

A

Burns

71
Q

Copper Sulfate is commonly used to disinfect _____.

A

water

72
Q

Zinc Chloride is often used in which two hygiene items?

A

Anti-Dandruff Shampoo & Mouthwash

73
Q

Used often as a Disinfectant during Embalming

A

Quaternary Ammonium Compounds

74
Q

Used to Treat Cold Sores

A

Quaternary Ammonium Compounds

75
Q

Common Chemical Food Preservatives

A

Sulfur Dioxide
Sodium Benzoate
Sorbic Acid
Calcium Propionate
Nitrates and Nitrites

76
Q

Why are Aldehydes Effective Antimicrobials?

A

they cross-link proteins inside of a cell making them unable to function properly

77
Q

Used to Preserve Cadavers

A

Formalin

78
Q

Cidex (2% Glutaraldehyde)

A

a liquid sterilant and can kill endospores

79
Q

Explain How Ethylene Oxide Gas Works Against Microbes

A

it cross-links proteins inside of a cell making them unable to function properly

80
Q

Two Methods often used to Sterilize Laparoscopes

A

Plasmas and Supercritical Fluids

81
Q

Often Used in Water Purification Systems

A

Ozone

82
Q

Why is Peroxide Ineffective for Cleaning Wounds?

A

our cells contain catalase which turns the H2O2 into water and oxygen gas

83
Q

Name the 4 Microbes that are Most Restistant to Chemical Biocides

A

Prions
Endospores
Mycobacterium (waxy cell walls)
Cysts of Protozoa

84
Q

Which is more reistant to chemical biocides? Gram Negative or Gram Positive Bacteria?

A

Gram-Negative

85
Q

TSE

A

Transmissible Spongiform Encephalopathies

86
Q

Bovine Spongiform Encephalopathy AKA

A

Mad Cow Disease

87
Q

Name Two Common Prion Diseases

A

Mad Cow Dieseas
Creutzfeld-Jakob Disease

88
Q

How is Mad Cow Disease Transmitted?

A
  • eating contaminated meat
  • genetic defect
  • transplant of infected organs
89
Q
A

Microbiology (22 decks)

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