Chapter 11 Flashcards
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
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
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
4
Q
Sterilization/ Sterile/ Sterilant
A
process by which everything is killed
-absence of life
5
Q
Disinfection/ Disinfectant
A
destruction of vegetative pathogens on inanimate objects
6
Q
Antisepsis/ Antiseptic
A
chemicals applied to body surfaces to destroy or inhibit vegetative pathogens
7
Q
Decontamination
A
destruction, removal, reduction in number of desirable microbes
8
Q
Degermination (Degerming)
A
cleaning technique that removes microbes and debris from living tissue
9
Q
Sanitization
A
cleansing technique that removes microbes and debris from inanimate objects
10
Q
Sepsis/ Septic/ Septicemia
A
contamination in blood
11
Q
Asepsis/ Aseptic/ Aseptic Technique
A
technique without bringing contamination
-without contamination
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)
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
14
Q
Suffix: ‘Cide/ ‘Cidal
A
“Kill”
ex: bactericide, bactericidal
15
Q
Suffix: ‘Static
A
“inhibit”
ex: Bacteriostatic, Fungistatic
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
17
Q
Conditions Influencing Microbial Control
A
- population size
- population composition
- effectiveness of agent
- mode of action of agent
- temperature
- toxicity
- environmental influences
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
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
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
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
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
23
Q
Conditions Influencing Microbial Control: Temperature
A
- microbes temperature response group
- effect of temperature changes on rates of reactions
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)
25
Conditions Influencing Microbial Control: Environmental Influences
```
-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
```
26
Heat
-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
27
Measurement Defined to Quantify killing power of heat: TDP (Thermal death Point)
lowest temperature at which all microbes in suspension killed in 10 minutes
28
Measurement Defined to Quantify Killing Power of Heat: TDT (Thermal death Time)
minimum time required to kill all microbes in liquid at given temperature
29
Measurement Defined to Quantify Killing Power of Heat: DRT (or D value) (Decimal Reduction Time)
time required to kill 90% of microbe population at given temperature
e.g. D50 = 1 minute
30
Moist Heat
-Mode of Action: denaturation of proteins
-Time to Act: penetrates quickly
3 Methods:
>Boiling
>Autoclave
>Pasteurization
31
Moist Heat: Boiling
100 Degrees Celsius/ 212 Degrees F
- boiling destroys most vegetative cells of bacteria and fungi (30 Minutes)
- boiling inactivates some viruses
32
Moist Heat: Autoclave
- 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)
33
Limitations of Autoclave
- 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)
34
Moist Heat: Pasteurization
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)
35
Equivalent Methods to Pasteurization
- 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)
36
UHT
Ultra High Temperature Processing (UHT)
-74 Degrees celsius-->134 Degrees celsius--> 74 Degrees
(In less than 5 seconds)
37
Dry Heat
-Mode of Action: Oxidation
-Time to Act: penetrates slowly
>Direct Flaming
>Incineration
>Hot Air Oven
38
Dry Heat: Direct Flaming
Bunsen Burner flame (up to 1800 Degrees Celsius)
39
Dry Heat: Incineration
- Infrared Incinerators (up to 800 Degrees Celsius)
| - Furnace (up to 6500 Degrees Celsius)
40
Dry Heat: Hot Air Oven
170 Degrees Celsius (2 hours)
| 150 Degrees Celsius to 180 Degrees Celsius for 2 to 4 hours
41
Other Physical Methods of Control: Radiation
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
Radiation: Non-ionizing Radiation
-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
Radiation: Ionizing Radiation
- Gamma Rays (less than 1 nm)
- Penetrating
- Mode of Action: dislodge electrons (e-) from atoms, create ions
44
Radura Symbol
symbol symbolizes food has been irradiated
45
Refrigeration
'static- inhibit
| to everything except psychrophiles (like the cold
46
Freezing
'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
Desiccation
- Dehydrator: removes moisture; slows growth
| - Osmotic Pressure: Plasmolysis
48
Microwave
possible things can be killed but not a reliable sterilizzer
49
Filtration
Separation of organisms from liquid or air
- Air: Hepa Filters (removes > 0.3 um)
- Liquid: Pore size critical; 0.01um for sterility
50
Lyophilization
freeze drying
- culture preservation method
ex: powder in a tube; if want to reproduce add water + incubate
51
Chemical Methods of Control
-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
Selecting Chemical Control Method
-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
Evaluating effectiveness of Chemical Agents
-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
Evaluating Effectiveness of Chemical Agents: Phenol Coefficient
former standard
55
Evaluating Effectiveness of Chemical Agents: Disk Difussion Method
- Kirby-Bauer Method (used in teaching labs)
| - Positive sensitivity test; zone of inhibition (area around disk no growth)
56
Evaluating Effectiveness of Chemical Agents: 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))
57
Chemical Antimicrobial Agents
- 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
Chemical Antimicrobial Agents: Phenol
(standard of comparison)
| -derived from the distillation of coal tar
59
Chemical Antimicrobial Agents: Phenolics
- phenol derivatives; disrupts membranes
| - consists of one or more aromatic carbon rings with added functional groups
60
Chemical Antimicrobial Agents: Hexachlorophene
(PHisohex)
| a chlorinated phenol
61
Chemical Antimicrobial Agents: Cresol
(Lysol)
| an alkylated phenol
62
Chemical Antimicrobial Agents: Triclosan
(Triclocarbon)
| in antimicrobial soaps
63
Chemical Antimicrobial Agents: Chlorhexidene
(Hibiclens + Hibistat)
| contains chlorine and two phenolic rings
64
Alcohols
- 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
Aldehydes
Organic substances with a -CHO on the terminal carbon
- Mode: protein denaturation
- Formaldehyde
- Glutaraldehyde
- Ortho-phthalaldehyde
66
Aldehydes: Formaldehyde
sharp, irritating gas, readily dissolves in water; 37% aqueous solution = formalin; carcinogen
67
Aldehydes: Glutaraldehyde
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
Aldehydes: Ortho- phthalaldehyde (OPA)
stable, nonirritating, similar action to glutaraldehyde but faster acting
-Disadvantage: inability to reliably destroy endospores + stains proteins in human skin
69
Heavy Metals
- 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
Disadvantages of Heavy Metals
- 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
Gaseous Chemosterilizers
-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
Gaseous Chemosterilizers: Ethylene Oxide (ETO)
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
Halogens
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
Halogens: Chlorene
- 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
Halogens: Iodine
- Mode: inhibits protein function; oxidation; similar to chlorine
- Tincture (alcohol), aqueous (water) Iodophor (detergent = Betadine)
76
Surfactants (surface acting agents)
-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
Surfactants: Soaps + Detergents
mechanical removal
78
Surfactants: Anionic Detergents
sanitizers (dairy, food)
79
Surfactants: Cationic Detergents
more effective die to amphipathic nature
80
Surfactants: Quaternary Ammonium Compounds (QUATS)
-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
Peroxygens (oxidizing agents)
- Ozone
- Hydrogen Peroxide
- Peracetic Acid
82
Peroxygens: Hydrogen Peroxide
- 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
Peroxygens: Peracetic Acid (C2H4O3)
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
Dyes
used in staining procedures and in selective and differential media
-Mode: interfere with replication; block cell wall synthesis
>aniline dyes
>acridine
>carbol fuchsin
85
Dyes: Aniline Dyes
(crystal violet + malachite green)
- effective against gram (+) bacteria and various fungi
- used in solutions and ointments to treat skin infections
86
Dyes: Acridine
antisepsis and wound treatment in medical and veterinary clinics
87
Dyes: Carbol Fuchsin
a phenolic
88
Plant Oils
-Thymol (thyme)- preservative
-Eugenol (cloves)- disinfect cavities
(if not diluted are powerful and can burn skin)
