A: Environmental Control Flashcards
sterilization (sterilant)
-100% destruction of microorganisms (≠prions)
-However, only eradication of harmful microorganisms
» i.e. Commercial sterilization
» i.e. Laboratory sterilization
asepsis
Environment or procedure free of pathogens
Disinfection:
use of?
to?
aka?
-Use of Chemical methods (disinfectants) and Physical methods
–To eradicate microorganisms, especially pathogens on inanimate objects
–“Sanitation”
antisepsis
living surfaces
“antiseptics”
de-germing
-Physical/Mechanical removal of microorganisms while using chemical methods
method etymology
-static/-stasis: indicating inhibition but not complete destruction of a type of microbe
-cidal/-cide: indicating destruction of a type of microbe
death rate:
Calculation of death under strict conditions
* Eradication per minute
* Constant rate
external vs internal microbial considerations
*External: Cellular integrity: Cell Wall, Cell Membrane
*Internal: Cellular Metabolism: Proteins, Nucleic Acids
cell considerations include
protein structure
double stranded or single
gram neg or pos
cell membrane
factors affecting antimicrobial methods:
Site treated (Location):
-Patient vs. Environment
-Patient: Location, Exposure
Susceptibility: Composition
Environmental conditions:
– Temperature
– pH
– Pressure
– Radiation
physical methods include:
-Temperature: Heat, Cold
-Desiccation
-Filtration
-Osmotic Pressure
-Radiation
temperature:
what can heat disrupt?
terminology?
Heat Disrupts Proteins (Denaturation), Nucleic Acids (Melting) and Lipid Layers / Walls (Disruption)
Terminology:
–Thermal Death Point: Minimal Temp for complete microbial death in 10min
–Thermal Death Time: Minimal time for complete
microbial death at a set Temp
–Decimal Reduction Time
moist heat:
-Employed for Convection: Air vs. Water
-Boiling”:
– ~100°C / 10min: Vegetative cells (bacteria,
fungi, protozoa, some viruses)
–Not endospores, cysts, some viruses: 20h
-Recommended for housewares and routine
utensils
moist heat: autoclaving
-Boiling limits = Steam
-Pressure combination with Heat: 15 PSI, 121°C
-Markers for sterilization: Tape, Color, Bacillus stearothermophilus
moist heat: pasteurization
-Non-sterilizing: Thermoduric, thermophilic
exceptions
-does a body good
dry heat:
-Ovens: Used when water is not an option, Decreased efficacy
–15m vs. 16h (autoclave)
Incineration
1. Air valve closed (long, flame)
2. Air valve nearly fully closed (skinnier controlled red orange flame)
3. Air valve semi-opened (purple smaller flame)
4. Air valve maximally opened (blue smallest flame)
cold
-Reduction of microbial metabolism (growth & reproduction)
Refrigeration: 0C - 7C
Freezing: lower than 0C, slow freezing advantage
drying
-desiccation
-lyophilization
Desiccation: Oldest method of preservation
-Removes most water: Metabolism, Propagation
-Not anti-fungal
Lyophilization:
*Freezing + Desiccation: Sublimation
*Permits reconstitution: No ice crystals
filtration:
seperation
-Separation: Physical sieving with Cells or viruses
Vacuum-assisted
Glass, porcelain, cotton, asbestos
*Common: Nitrocellulose: 0.01μm-25μm
osmosis:
osmotic pressure
-Osmotic Pressure: High concentrations of
solutes like Salt or Sugar
-Hypertonic solutions: Crenation (desiccation)
-Used for preservation: Not anti-fungal
radiation:
what is it?
types?
-Particulate & Electromagnetic. it is High-speed traveling at Light (3 x108 m/s). it has Subatomic particles (Particulate) like Protons. it has Energy Emission by Waves. Wavelength-based are γ-rays, x-rays, and UV.
Radiation Types:
* Ionizing: < 1nm λ, Remove electrons (Ionizing), Affect Bonds and ROS’s. Causes Denaturation and Mutation. Types include e neg. beams, γ-rays, x-rays. Commonly used in food ~ Near UV
-ultraviolet, x-rays, gamma rays
-radioactive chemicals, x-rays, sun
- Non-ionizing: > 1nm λ. Causes Denaturation and Mutation
– **UV (260nm)
-infrared, microwaves, radio waves,
-tv remote, radar, cell phones, TV, FM/AM
compounds:
phenolics?
cons?
-Phenol(ics): a.k.a. Carbolic acid, standard of comparison
alcohols
-Largely non-polar: Require water for efficacy, May be combined with other antimicrobial agents like Tinctures
-Effective towards Bacteria, Fungi, Viruses
-Not-Effective towards Endospores, fungal spores
-Reps:
Isopropanol [IPA], Ethanol
[EtOH]
halogens
-Gp VIIA on Periodic Table: I, Cl, Br, F and ILGs
-Putative oxidizers: Anti-enzymatic
-Effective: Vegetative bacteria, some spores (bacterial, fungal), and protozoan cysts
-Reps:
– Iodine, NaOCl, CaOCl, F
oxidizers
-Loss of e- ≡ Oxidation
-HLGs: Anti-enzymatic, Notable against anaerobes (Deep wounds)
-Reps:
Peroxides, Ozone, Peracetic Acid (Sporicide)
surfactants
-Decrease surface tension
-Increase concentration of antimicrobial
-LLGs: Bacteria (G+), Fungi, Env. Viruses
Reps:
-Soaps: Bipolar compounds, Concentrate oil + organisms
-Detergents: Cationic compounds (Quaternary NH4+), Disrupt membranes
what are the chemical substances methods?
phenolics
alcohol
halogens
oxidizers
surfactants
aldehydes
gases
elements:
-Heavy Metals:
-Sulfur-chelating metals: Zn, Hg, Ag, Cu
-Anti-enzymatic: Denatures proteins
-LLGs
-Reps:
–Ag: Silver bullets
–Hg: Thimerosal
–Cu: Water-based treatments
aldehydes
-Functional Group
-Cross-linker
-Anti-enzymatic: Denatures protein amino, hydroxyl, sulfhydryl, and carboxyl groups
-Anti-Nucleic Acid: Permanently cross-links DNA + RNA
-Reps:
–Formaldehyde: Formalin (37%), Preservative
gases:
-Bulk-based cross-linker
-Chamber-based
-Cons: Low-efficacy, Carcinogenic
-Reps:
–Ethylene oxide, propylene oxide, and beta-propiolactone
organics:
-Enzymes:
-Natural methods: Tears, Saliva, Gastrics
-Sources: Human, Fungal, Bacterial
-“Antimicrobials”
-Cutting-edge research: Animals
LLG
Low Level Germicides
-enveloped viruses
-gram-postive bacteria
-naked viruses
ILG
Intermediate Level Germicides
-fungi
-gram-negative bacteria
-protozoa (trophozoites)
HLG
High Level Germicides
-protozoan
-cysts
-mycobacteria
-endospores
-prions (highest)
