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Microbiology > Chapter 11 > Flashcards

Chapter 11 Flashcards

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1
Q

Semmelweis

A
  • correlated infections with physicians coming directly from the autopsy room to the maternity ward
  • instituted washing hands with chlorinated lime
  • reduced incidence of childbirth fever
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2
Q

Lister

A
  • credit for aseptic technique in surgery
  • introduced aseptic technique in surgery to reduce microbes in medical settings and prevent wound infections
  • used carbolic acid (phenol) as disinfectant
  • used heat
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3
Q

Pasteur

A
  • developed pasteurization
  • disproved spontaneous generation of microorganisms
  • credit for aseptic technique in the lab
  • showed microbes caused fermentation and spoilage
  • microbes are everywhere
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4
Q

Sterilization/ Sterile/ Sterilant

A

process by which everything is killed

-absence of life

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5
Q

Disinfection/ Disinfectant

A

destruction of vegetative pathogens on inanimate objects

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6
Q

Antisepsis/ Antiseptic

A

chemicals applied to body surfaces to destroy or inhibit vegetative pathogens

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7
Q

Decontamination

A

destruction, removal, reduction in number of desirable microbes

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8
Q

Degermination (Degerming)

A

cleaning technique that removes microbes and debris from living tissue

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9
Q

Sanitization

A

cleansing technique that removes microbes and debris from inanimate objects

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10
Q

Sepsis/ Septic/ Septicemia

A

contamination in blood

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11
Q

Asepsis/ Aseptic/ Aseptic Technique

A

technique without bringing contamination

-without contamination

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12
Q

Decreasing Order of Resistance of Microorganisms

A
  • Prions (most resistant)
  • Endospores of bacteria
  • Mycobacteria
  • Cysts of Protozoa
  • Vegetative protozoa
  • Gram Negative bacteria
  • Fungi, including most fungal spores
  • Viruses without envelopes
  • Gram Positive bacteria
  • Viruses with liquid envelopes (least resistant)
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13
Q

Degree of Action of Antimicrobial Substances

A

-Root + Suffix
-Root: type of microbe
-Suffix: type of action
>’cide/ cidal= kill
>’static= inhibit

ex: bactericide, bactericidal, bacteriostatic, fungicide, fungicidal, fungistatic, microbicide, sporicidal, viricidal

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14
Q

Suffix: ‘Cide/ ‘Cidal

A

“Kill”

ex: bactericide, bactericidal

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15
Q

Suffix: ‘Static

A

“inhibit”

ex: Bacteriostatic, Fungistatic

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16
Q

Concepts of Microbial Control

A

Different Species = Different DNA
= Different growth requirements (nutrition, pH, oxygen, water)
= Different response to temperature, chemicals
= Different ability to produce endospores

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17
Q

Conditions Influencing Microbial Control

A
  • population size
  • population composition
  • effectiveness of agent
  • mode of action of agent
  • temperature
  • toxicity
  • environmental influences
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18
Q

Conditions Influencing Microbial Control: Population Size

A
  • bacterial populations subjected to heat or antimicrobial substances usually die at a constant rate
  • the time it takes to kill a microbial population is proportionate to the number of microbes
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19
Q

Conditions Influencing Microbial Control: Population Composition

A 
The target population is usually a mixture of species
-by nature, microorganisms differ in their susceptibility to heat and antimicrobial agents 
-susceptibility is Species Specific
-Species differ in:
>presence of capsule
>cell wall components
>response to temperature
>ability to produce endospores
>phase of bacterial growth curve
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20
Q

Population Composition: Susceptibility

A 
Species Specific
-Species Differ in: 
>presence of capsule
>cell wall components
>response to temperature
>ability to produce endospores
>phase of bacterial growth curve
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21
Q

Conditions Influencing Microbial Control: Effectiveness of Agent

A

effectiveness of chemical antimicrobial agents is affected by:

  • concentration
  • time
  • method of application
  • temperature
  • pH
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22
Q

Conditions Influencing Microbial Control: Mode of Action of Agent (how does agent kill or inhibit microbes)

A

-alteration of permeability of membrane
-blocking synthesis, digesting or breaking down cell wall
-protein damage
-denaturation
>interference with synthesis at any stage
-nucleic acid damage
-deleterious mutation
-thymine dimers

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23
Q

Conditions Influencing Microbial Control: Temperature

A
  • microbes temperature response group

- effect of temperature changes on rates of reactions

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24
Q

Conditions Influencing Microbial Control: Toxicity

A

effect of agent or method on tissue (applier/ apliee) as well as on inanimate objects (counter, material)

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25
Q

Conditions Influencing Microbial Control: Environmental Influences

A 
-amount/ type of material
>presence of interfering organic matter
>presence of biofilms
>nature of suspension medium (presence of solvents, presence of inhibitors)
-Ambient temperature
-Ambient pH
-Length of exposure
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26
Q

Heat

A

-Principles of heat killing
>heat is the preferred agent of sterilization for all materials not damaged by it
-measurements defined to quantify killing power of heat:
>TDP- thermal death point
>TDT- thermal death time
>DRT (or D value)- Decimal reduction time

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27
Q

Measurement Defined to Quantify killing power of heat: TDP (Thermal death Point)

A

lowest temperature at which all microbes in suspension killed in 10 minutes

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28
Q

Measurement Defined to Quantify Killing Power of Heat: TDT (Thermal death Time)

A

minimum time required to kill all microbes in liquid at given temperature

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29
Q

Measurement Defined to Quantify Killing Power of Heat: DRT (or D value) (Decimal Reduction Time)

A

time required to kill 90% of microbe population at given temperature
e.g. D50 = 1 minute

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30
Q

Moist Heat

A

-Mode of Action: denaturation of proteins
-Time to Act: penetrates quickly
3 Methods:
>Boiling
>Autoclave
>Pasteurization

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31
Q

Moist Heat: Boiling

A

100 Degrees Celsius/ 212 Degrees F

  • boiling destroys most vegetative cells of bacteria and fungi (30 Minutes)
  • boiling inactivates some viruses
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32
Q

Moist Heat: Autoclave

A
  • Pressure: 15 psi (pounds per square inch)
  • Temperature: 121 Degrees Celsius
  • Time: 15 to 20 minutes (depending on volume and distribution of load)

-Effectiveness:
>all vegetative organisms
>endospores
>disrupts nucleic acid structure of viruses

(can only adjust pressure to get hight temperature for autoclave)

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33
Q

Limitations of Autoclave

A
  • Penetration required (wrapping in foil not recommended)
  • material to be autoclaved needs to be heat resistant
  • prions require 134 Degrees Celsius (so you need to raise pressure for higher temp)
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34
Q

Moist Heat: Pasteurization

A

process that kills most pathogens and lowers the total number of bacteria so that food wont spoil rapidly at refrigerator temperatures
(not sterilization, only reduces #’s)

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35
Q

Equivalent Methods to Pasteurization

A
  • Flash Method: 72 Degrees celsius, 15 seconds (modern method; continuous method; called HTST- high temp short time)
  • Holding Method: 63 Degrees celsius, 30 minutes (classic method; batch method)
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36
Q

UHT

A

Ultra High Temperature Processing (UHT)
-74 Degrees celsius–>134 Degrees celsius–> 74 Degrees
(In less than 5 seconds)

37
Q

Dry Heat

A

-Mode of Action: Oxidation
-Time to Act: penetrates slowly
>Direct Flaming
>Incineration
>Hot Air Oven

38
Q

Dry Heat: Direct Flaming

A

Bunsen Burner flame (up to 1800 Degrees Celsius)

39
Q

Dry Heat: Incineration

A
  • Infrared Incinerators (up to 800 Degrees Celsius)

- Furnace (up to 6500 Degrees Celsius)

40
Q

Dry Heat: Hot Air Oven

A

170 Degrees Celsius (2 hours)

150 Degrees Celsius to 180 Degrees Celsius for 2 to 4 hours

41
Q

Other Physical Methods of Control: Radiation

A
  1. Non-ionizing Radiation:
    -UV light (1-380nm; below 260 nm best);
    >sunlight (>295nm - 380nm)
    -Limitation: non penetrating
    -Mode of Action: damages DNA by causing formation of bonds between adjacent pyrimidine bases (usually thymine dimers)
  2. Ionizing Radiation
    - Gamma rays (less than 1 nm)
    - Penetrating
    - Mode of Action: dislodge electrons from atoms, create ions
42
Q

Radiation: Non-ionizing Radiation

A

-UV light (1-380nm; below 260nm best);
>sunglight (>295nm - 380nm)
-Limitation: non penetrating
-Mode of Action; damages DNA by causing formation of bonds between adjacent pyrimidine bases (usually thymine dimers)

43
Q

Radiation: Ionizing Radiation

A
  • Gamma Rays (less than 1 nm)
  • Penetrating
  • Mode of Action: dislodge electrons (e-) from atoms, create ions
44
Q

Radura Symbol

A

symbol symbolizes food has been irradiated

45
Q

Refrigeration

A

‘static- inhibit

to everything except psychrophiles (like the cold

46
Q

Freezing

A

‘static- inhibit
(normal vs deep freezing)
-deep freezing- freezing to a temp way below 0 (use in crime cases to preserve for a while)
-flash frozen- less disruption; more likely to get sick

47
Q

Desiccation

A
  • Dehydrator: removes moisture; slows growth

- Osmotic Pressure: Plasmolysis

48
Q

Microwave

A

possible things can be killed but not a reliable sterilizzer

49
Q

Filtration

A

Separation of organisms from liquid or air

  • Air: Hepa Filters (removes > 0.3 um)
  • Liquid: Pore size critical; 0.01um for sterility
50
Q

Lyophilization

A

freeze drying

  • culture preservation method
    ex: powder in a tube; if want to reproduce add water + incubate
51
Q

Chemical Methods of Control

A

-There are a few reliable chemical sterilizers
-Realistic Goal: reduction of microbial numbers
-No one chemical appropriate for all conditions or all microbes
-Considerations for use:
>proper mixing
>concentration
>application

52
Q

Selecting Chemical Control Method

A

-rapid action in low concentrations
-resistance to inactivation by presence of organic matter
-effective against a wide range of microbial agents (broad spectrum) without being toxic to human and animal tissue
-easily penetrate material (without damaging or discoloring material)
-solubility in water or alcohol and long-term stability
-easy to prepare
-stability in environmental conditions
-availability; affordability
long shelf life; non-offensive odor

53
Q

Evaluating effectiveness of Chemical Agents

A

-Phenol Coefficient (former standard)
-Disk Diffusion Method
>Kirby- Bauer method (used in teaching labs)
>Positive Sensitivity Test: zone of inhibition (area around disk showing no growth)
-USE-Dilution Test
>current standard (uses preparations of test bacteria)
>most effective: agent that prevents growth at greatest dilution (no growth- minimum inhibitory concentration (MIC))

54
Q

Evaluating Effectiveness of Chemical Agents: Phenol Coefficient

A

former standard

55
Q

Evaluating Effectiveness of Chemical Agents: Disk Difussion Method

A
  • Kirby-Bauer Method (used in teaching labs)

- Positive sensitivity test; zone of inhibition (area around disk no growth)

56
Q

Evaluating Effectiveness of Chemical Agents: USE-Dilution Test

A
  • current standard (uses preparations of test bacteria)

- most effective: agent that prevents growth at greatest dilution (no growth- minimum inhibitory concentration (MIC))

57
Q

Chemical Antimicrobial Agents

A
  • Phenol: (standard of comparison) derived from the distillation of coal tar
  • Phenolics: phenol derivatives; disrupt membranes, consists of one or more aromatic carbon rings with added functional groups
  • Hexachlorophene (PHisohex): a chlorinated phenol
  • Cresol (lysol): an alkylated phenol
  • Triclosan (Triclocarbon): in antimicrobial soaps
  • Chlorhexidene (Hibiclens + Hibistat): contains chlorine and two phenolic rings
58
Q

Chemical Antimicrobial Agents: Phenol

A

(standard of comparison)

-derived from the distillation of coal tar

59
Q

Chemical Antimicrobial Agents: Phenolics

A
  • phenol derivatives; disrupts membranes

- consists of one or more aromatic carbon rings with added functional groups

60
Q

Chemical Antimicrobial Agents: Hexachlorophene

A

(PHisohex)

a chlorinated phenol

61
Q

Chemical Antimicrobial Agents: Cresol

A

(Lysol)

an alkylated phenol

62
Q

Chemical Antimicrobial Agents: Triclosan

A

(Triclocarbon)

in antimicrobial soaps

63
Q

Chemical Antimicrobial Agents: Chlorhexidene

A

(Hibiclens + Hibistat)

contains chlorine and two phenolic rings

64
Q

Alcohols

A
  • colorless hydrocarbons with one or more -OH groups
  • Mode: protein denaturation; lipid dissolution
  • ‘Cidal except endospores + viruses
  • Advantage: fast acting; evaporates; no residue
  • Disadvantage on open wounds: coagulation of protein layer
  • Concentration: 60 to 95% effective; 70% optimal
  • Usage: alone in aqueous solutions or as solvents for tinctures (alcohol mixed with something else)
65
Q

Aldehydes

A

Organic substances with a -CHO on the terminal carbon

  • Mode: protein denaturation
  • Formaldehyde
  • Glutaraldehyde
  • Ortho-phthalaldehyde
66
Q

Aldehydes: Formaldehyde

A

sharp, irritating gas, readily dissolves in water; 37% aqueous solution = formalin; carcinogen

67
Q

Aldehydes: Glutaraldehyde

A

rapid, broad spectrum, one of few chemicals officially accepted as sterilizing agent

  • Kills endospores in 3 hours
  • Kills fungi and bacteria including Pseudomonas and Mycobacterium in few minutes
  • Inactivates viruses in short time
  • 2% solution cidex sproicidal in 3 - 10 hours
68
Q

Aldehydes: Ortho- phthalaldehyde (OPA)

A

stable, nonirritating, similar action to glutaraldehyde but faster acting
-Disadvantage: inability to reliably destroy endospores + stains proteins in human skin

69
Q

Heavy Metals

A
  • Silver, Mercury, Gold, Sulfur, Copper, Arsenic, Selenium, Zinc
  • Denature proteins (by binding to functional groups of proteins and inactivating them)
  • Oligodynamic action (property of having antimicrobial effects in exceedingly small amounts)
  • Silver + Mercury are effective Biocides
  • Silver Nitrate AgNO3
  • Sulfure dioxide
  • Merthiolate (thimerosal = Hg + sodium)
  • Copper Sulfate
  • Selenium
70
Q

Disadvantages of Heavy Metals

A
  • metals are very toxic to humans if ingested, inhaled, or absorbed through the skin… even in small quantities
  • commonly cause allergic reactions
  • biological fluids and wastes neutralize their actions
  • microbes can develop resistance to metals
71
Q

Gaseous Chemosterilizers

A

-vapors and aerosols having broadest applications:
>Propylene oxide
>Chlorine Dioxide
>Ethylene Oxide (effective sterilizer)
-Mode: reacts vigorously with functional groups of proteins and DNA
-sterilize in closed chamber without heat
-used for medical supplies, equipment
-Ethylene Oxide (ETO)

72
Q

Gaseous Chemosterilizers: Ethylene Oxide (ETO)

A

one of very few generally accepted for chemical sterilization because sporicidal if used correctly
-penetrating
-slow-acting (90 minutes to 3 hours; mattresses 14 hours)
-residues absorbed; items need to be aerated for several hours
-explosive
-carcinogenic
(ETO Explosive in air unless combined with CO2)

73
Q

Halogens

A

Nonmetallic elements that share similar chemical properties
-Mode: oxidizing agents in absence of organic matter
microbe death occurs within 30 minutes
-endospores require several hours
-less effective and relatively unstable if exposed to light, alkaline pH, excess organic matter
>Chlorine
>Iodine

74
Q

Halogens: Chlorene

A
  • Major forms: liquid and gaseous chlorine Cl2; hypochlorites OCl; chloramines NH2Cl
  • compounds combine with water to form strong oxidizing agent: hypochlorous acid
  • Cl gas used to disinfect water; Cl compounds used in dairies, for household use
75
Q

Halogens: Iodine

A
  • Mode: inhibits protein function; oxidation; similar to chlorine
  • Tincture (alcohol), aqueous (water) Iodophor (detergent = Betadine)
76
Q

Surfactants (surface acting agents)

A

-Mode: decrease surface tensions among molecules of a liquid; dissolve lipids; disrupt membranes; denature proteins
-Soaps + Detergents: mechanical removal
-Anionic Detergents: sanitizers (dairy, food)
-Cationic Detergents: more effective die to amphipathic nature
-Quaternary Ammonium Compounds (QUATS)
>antiseptic for skin, mouth, rubber
>effectiveness reduced in presence of organic matter
>require alkaline pH to function
>doesnt work on M. Tuberculosis, Hepatitis virus, endospores
>Zephiran, Cepacol
(Pseudomonas aeruginosa actively grows in QUATS)

77
Q

Surfactants: Soaps + Detergents

A

mechanical removal

78
Q

Surfactants: Anionic Detergents

A

sanitizers (dairy, food)

79
Q

Surfactants: Cationic Detergents

A

more effective die to amphipathic nature

80
Q

Surfactants: Quaternary Ammonium Compounds (QUATS)

A

-antiseptic for skin, mouth, rubber
-effectiveness reduced in presence of organic matter
-require alkaline pH to function
-doesn’t work on M. Tuberculosis, Hepatitis virus, Endospores
-Zephiran, Cepacol
(Pseudomonas aeruginosa actively grows in QUATS)

81
Q

Peroxygens (oxidizing agents)

A
  • Ozone
  • Hydrogen Peroxide
  • Peracetic Acid
82
Q

Peroxygens: Hydrogen Peroxide

A
  • colorless, caustic liquid that decomposes in presence of light, metals or catalase
  • antiseptic: ineffective on open wounds (2H2O2-catalase–>2H2O + O2)
  • disinfectant: effective on surfaces and unbroken skin
  • bactericidal; virucidal; fungicidal
  • sporicidal at higher concentrations or if applied at high temperatures
83
Q

Peroxygens: Peracetic Acid (C2H4O3)

A

most effective liquid chemical sterilizer

  • effective within 5 to 30 minutes
  • no toxic residues
  • used in food industry; water cooling towers; to sterilize rooms; the space shuttle; decontamination of large areas
84
Q

Dyes

A

used in staining procedures and in selective and differential media
-Mode: interfere with replication; block cell wall synthesis
>aniline dyes
>acridine
>carbol fuchsin

85
Q

Dyes: Aniline Dyes

A

(crystal violet + malachite green)

  • effective against gram (+) bacteria and various fungi
  • used in solutions and ointments to treat skin infections
86
Q

Dyes: Acridine

A

antisepsis and wound treatment in medical and veterinary clinics

87
Q

Dyes: Carbol Fuchsin

A

a phenolic

88
Q

Plant Oils

A

-Thymol (thyme)- preservative
-Eugenol (cloves)- disinfect cavities
(if not diluted are powerful and can burn skin)

Microbiology (20 decks)

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