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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 amphipathic 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 has 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
3 Main Methods of Damaging Microbes
- Heat - Chemicals - Radiation
25
Factors Affecting the Rate of Microbial Death
- Number of Microbes - Presence of Organic Debris - pH - Temp - Nature of Suspending Medium - Time of Exposure - Characteristics of the Microbe Being Attacked
26
Desiccation
creating a hypertonic environment to dehydrate cells
27
Is desication effective against endospores?
No
28
Is desiccation effective against viruses?
No
29
Is desiccation effective against most bacteria?
Yes
30
Why are low temps effective against microbes?
It decreases the metabolic rate against most microbes so they cannot grow or produce toxins easily
31
Thermal Death Point
the lowest temperature at which all microbes in a suspension can be killed in 10 minutes
32
Thermal Death Time
the minimum length of time it would take to kill all bacteria in a liquid culture at a certain temp
33
Dismal Retention Time
the length of time it will take to kill 90% of microbes in a suspension at a given temp
34
How long should something boil to kill most of the microbes?
10 minutes
35
How resistant are endospores to boiling?
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
36
Autoclaving
a true and effective sterilization method uses moist heat at 121 C at 15 psi for 15 minutes to sterilize metal and glass
37
prion
infectious misfolded proteins
38
Can prions survive autoclaving?
Yes, some prions can survive autoclaving
39
Pastuerization
uses heat to destroy pathogens and reduce the number of microbes that can spoil food
40
Does pasturization change the nutritional composition of milk?
No
41
HTST
High Temperature, Short Time
42
HTST Pasturization AKA
Flash Pasturization
43
UHT
Ultra High Temperature
44
How long does it take to treat milk using HTST Pasteurization vs UHT Sterilization?
HTST takes 15 seconds whereas UHT takes 4 seconds
45
What method of treatment has Gossner's Milk undergone in order to be stored unrefridgerated on the shelf?
UHT Sterilization
46
Can UHT Sterilization kill endospores?
Yes
47
Three Methods of Dry-Heat Sterilization
Open Flame Heated Incinerator Hot Air Oven
48
Which method of serilization is faster? Moist Heat or Dry Heat?
Moist Heat
49
Two Methods Used to Sterilize Substances That Cannot Be Treated With Heat
Membrane Filtration High Pressure Radiation (ionizing or nonionizing)
50
What two microbes could potentially survive membrane filtration and why?
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
Two Types of Radiation
Ionizing Radiation Nonionizing Radiation
52
Ionizing Radiation
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
Non-Ionizing Radiation
uses UV light to create thymine dimers in the DNA which prevents DNA replication and transcription
54
Which type of radiation penetrates deeper? Ionizing or Nonionizing?
Ionizing
55
Why are microwave ovens beneficial in killing pathogens?
it generates heat which can denature proteins in microbes
56
What method was used to sterilize catheters and prevent UTIs in catheterized patients?
High-Intensity Narrow-Spectrum (HINS) Light
57
Two Methods Used to Evaluate a Disinfectant
- Use-Dilution Test - Disk-Diffusion Method
58
Expalin How the Disk-Diffusion Method Works to Evaluate a Disinfectant
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
Phenol works by ____.
Damaging Plasma Membranes
60
Name 4 Halogens
Fluorine Chlorine Bromine Iodine
61
Iodine and Iodophors works as an antiseptic by
inhibiting protein synthesis and altering cell membranes
62
Chlorine works as an antiseptic by
penetraiting cell walls and inhibit cellular enzymes
63
What dilution of bleach is recomended?
1 part chloride to 4 parts water
64
What percent of rubbing alcohol is most effective againt microbes?
70%
65
Why is 100% ethanol ineffective against microbes?
it evaporates too quickly and doesn't have sufficient time to destroy microbes
66
How does rubbing alcohol work against microbes?
It denatures proteins and dissolves lipids/disrupts plasma membranes
67
Oligodynamic Action
only a small amount is required in order to be effective
68
Heavy Metals are effective against microbes by
denaturing proteins
69
Examples of Heavy Metal Compounds Used to Combat Microbes
Silver Nitrate Silver Sulfadiazene Surfacine
70
Silver Sulfadiazene is often applied topically to treat ____.
Burns
71
Copper Sulfate is commonly used to disinfect _____.
water
72
Zinc Chloride is often used in which two hygiene items?
Anti-Dandruff Shampoo & Mouthwash
73
Used often as a Disinfectant during Embalming
Quaternary Ammonium Compounds
74
Used to Treat Cold Sores
Quaternary Ammonium Compounds
75
Common Chemical Food Preservatives
Sulfur Dioxide Sodium Benzoate Sorbic Acid Calcium Propionate Nitrates and Nitrites
76
Why are Aldehydes Effective Antimicrobials?
they cross-link proteins inside of a cell making them unable to function properly
77
Used to Preserve Cadavers
Formalin
78
Cidex (2% Glutaraldehyde)
a liquid sterilant and can kill endospores
79
Explain How Ethylene Oxide Gas Works Against Microbes
it cross-links proteins inside of a cell making them unable to function properly
80
Two Methods often used to Sterilize Laparoscopes
Plasmas and Supercritical Fluids
81
Often Used in Water Purification Systems
Ozone
82
Why is Peroxide Ineffective for Cleaning Wounds?
our cells contain catalase which turns the H2O2 into water and oxygen gas
83
Name the 4 Microbes that are Most Restistant to Chemical Biocides
Prions Endospores Mycobacterium (waxy cell walls) Cysts of Protozoa
84
Which is more reistant to chemical biocides? Gram Negative or Gram Positive Bacteria?
Gram-Negative
85
TSE
Transmissible Spongiform Encephalopathies
86
Bovine Spongiform Encephalopathy AKA
Mad Cow Disease
87
Name Two Common Prion Diseases
Mad Cow Dieseas Creutzfeld-Jakob Disease
88
How is Mad Cow Disease Transmitted?
- eating contaminated meat - genetic defect - transplant of infected organs

Microbiology (22 decks)

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