Control of Microbial Growth - 2 Flashcards
The use of low temperatures to usually inhibit or stop microbial growth and proliferation but often do not kill bacteria
Low Temperature
Temperature of this device can range from 0-7 degrees Celsius
This reduces the metabolic rate for most microbes
Refrigeration
inactivates any microbes — bacteria, yeasts and molds - - present in food. Once thawed, however, these microbes can again become active, multiplying under the right conditions to levels that can lead to foodborne illness
Freezing
used to freeze biological samples quickly so that large ice crystals cannot form and damage the sample
Does not kill most microbes
Flash Freezing
The use of a a low cooling rate and prevents intracellular ice formation (IIF) by dehydration of cells
Slow Freezing
Over ___ of bacteria can survive 1 year of being frozen. Most parasites are killed by ___ of freezing.
⅓
a few days
Otherwise known as drying, generally has a static effect on microorganisms. Lack of water inhibits the action of microbial enzymes
Desiccation
this microorganism survives 1 hour after desiccation
Neisseria Gonnorhea
is the minimum pressure that needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane
Osmotic pressure
It is also defined as the measure of the tendency of a solution to take in its pure solvent by osmosis.
Osmotic pressure
this microorganism survives several months after desiccation
Mycobacterium Tuberculosis
two viruses that can survive several months after desiccation
Clostridium and Bacillus -
Water leaving the cell
Plasmolysis
Resistant to high pressure
Yeasts and Molds
considerably more osmotolerant than other bacterial pathogens
Staphylococci
the emission or transmission of energy in the form of waves or particles through space or a material medium
Radiation
Gamma, x, electron, or higher energy rays
Causes mutations
Generally used for medical supplies
Disadvantage: Penetrates human tissue and causes genetic mutations
Ionizing radiation
Typically used on trichinosis, beef for E.Coli, salmonella
What germicidal lamps use
Ultraviolet Light
Wavelength of radiation is longer than 1 nanometer
Produces thymine dimers
Disadvantages: Damages skin and eyes. Doesn’t penetrate paper and other items.
Nonionizing Radiation
Wavelength = 1 mm - 1m
Trichinosis outbreak from pork cooked in microwaves
Does not affect microbes directly
Disadvantage: heating is uneven
Microwave Radiation
It causes breaks in DNA that further inhibit DNA and protein synthesis. It decreases the uptake of oxygen and nutrients that affect the growth of microorganisms and eventually leads to the killing of cells.
Halogens
It causes breaks in DNA that further inhibit DNA and protein synthesis. It decreases the uptake of oxygen and nutrients that affect the growth of microorganisms and eventually leads to the killing of cells.
Halogens
the the 3 main halogens in the disinfection category.
Fluorine (F), chlorine (Cl), and iodine (I)
fungicide, bacteriacide, and viricide are considered:
Germicides
bacteriostatic and fungistatic are considered
Germistatic
Destroy everything
For scalpels and other medical equipment
Examples include ethylene oxide gas and hydrogen peroxide
Sterilants
Do not reliably destroy endospores
For GI endoscopes
Examples include iodine, phenol, chlorhexidine, and silver nitrate
High-level Disinfectant
Will kill mycobacterium, but not destroy all viruses or endospores
For stethoscopes, electrodes, and thermometers
Includes ethyl and isopropyl alcohol
Intermediate Level Disinfectant
Will not kill mycobacterium
For clothes
Examples include soap and detergent
Low-level Disinfectant
Rarely used today because it is a skin irritant and has a strong odor
Used in some throat sprays and lozenges
Example of this is carbolic acid
Phenols and Phenolics
derivatives of phenol cresols
Derived from coal tar (Lysol)
Phenolics
For use against gram-positive staphylococcus and streptococci
Used in nurseries
Excessive use can lead to neurological damage
Destroys plasma membranes and denatures proteins
Advantages: Stable, persist for long times after being applied.
Biphenols (pH isoHex)
One of the 1st antiseptic
Iodine
Skin antiseptic in surgery
Slow releasing
Not effective against bacterial endospores
Examples include betadine and isodine
Iodophors
Forms hypochloric acid: Cl2 + H20 -> H + Cl- + HoCl
Used to disinfect drinking water, pools, and sewage
Chlorine
Denatures protein
Used to mechanically wipe off microorganisms
Not good for open wounds, causes proteins to coagulate
Alcohol
Drinking alcohol
70% is the optimum concentration for disinfecting
Ethanol
Rubbing alcohol
This might be best to use as a nurse
Isopropanol
This compound disinfectant is prepared by pure natural plants, and is rich in various natural organic acid, phenol and the like
Silver nitrate
Mild antiseptic
Colorless and caustic liquid
Forms hydroxyl free radicals
Effective against anaerobes
Skin and wound cleaner
Quick method for sterilizing medical equipment
Hydrogen Peroxide
is any organism that does not require molecular oxygen for growth
anaerobic organism or anaerobe
Copper, selenium, mercury, silver, zinc
Oligodynamic action
Heavy Metals
Menthiolate and mercurochrome
Mercury
Copper ___ is used to kill algae in pools
Copper sulfate
Heavy metal that kills fungi
Selenium
Zinc chloride for mouthwash
Zinc oxide as an antifungal agent in paint
Zinc
Surface active agents
Cationic (positively charged) detergents
Quaternary Ammonium Compounds (Quats)
