Chemical & Physical Methods of Control (BE #3) Flashcards
disinfectant
- reduces the # of pathogens to a level that poses no danger
- used on inanimate objects
antiseptic
- kills microbes or inhibits growth
- used on skin or living tissue
microbiocidal
treatment that kills molecules
microbiostatic
treatment that inhibits, rather than kills, microbes
sterilization
destroys all microbial life
commercial sterilization
food subjected to just enough heat to destroy Clostridium botulinum spores
2 advantages to using heat to control microbes
- simple
- inexpensive
What is the mode of action of heat?
denatures proteins
What is disadvantage to boiling?
doesn’t kill thermophiles or endospores; can change the flavor of some foods
Conditions for autoclaving
15-20 min, 15 psi, 121 degrees C
- the pressure raises the temp to above boiling
- disadvantage - can’t use with heat sensitive materials
What is the advantage of pasteurization?
doesn’t change the taste/appearance of food
- used in dairy products, wine, beer, “egg beaters”
What is the effect of using cold to control microbes?
microbiostatic - does not sterilize
MOA - slows down metabolic rate
2 types of radiation that kill bacteria & their mode of action
nonionizing (UV) & ionizing (x-rays, gamma rays)
MOA - mutates DNA
Sterilizes
What are the disadvantages of using UV light?
only kills on surfaces (doesn’t penetrate) & can be harmful to humans
2 types of ionizing radiation
Disadvantage to using this type?
How is it being used?
X-rays
gamma rays
MOA - strip electrons from atoms, which causes free radicals to form that damage other molecules in the cell, such as DNA
technically complex
meat, produce, grains, spices, poultry
Why is filtration replacing pasteurization in some cases?
causes even less damage to heat sensitive materials.
Used with antibiotics, beer
What are some microorganisms that can pass through a filter?
- Mycoplasma - no cell wall so can squeeze through small spaces
- spirochetes - corkscrew their way through small holes
- viruses - too small to stop
What is lyophilization?
freeze drying - materials are frozen & then the ice is turned to a gas.
Advantage - avoids chemical changes caused by heat drying
MOA - slows down metabolic rate;
Disadvantage - expensive
MOA of using high concentrations of salt or sugar?
creates a hypertonic environment & “sucks” the water out of bacterial cells
2 test organisms traditionally used to test germicides
Salmonella typhi
Staphylococcus aureus
disadvantage to using alcohol
evaporates quickly
doesn’t kill endospores
not good for wound treatment (causes coagulation of proteins, under which microbes can grow)
why is Staphylococcus relatively resistant to hydrogen peroxide (H2O2)?
Staph produces catalase & peroxidase, which H2O2 reacts with and turns to H2O & O2.
What is MOA of surfactants?
Penetrates oily substances in water & breaks them apart into small droplets that become coated with surfactant molecules. The hydrophobic end of the surfactant sticks into the droplets & the hydrophilic end is attracted to the water. The result is an emulsion, a fine suspension of oily droplets in water, which can now be rinsed away.
Advantage & disadvantage to using alkylating agents
advantage - they sterilize
disadvantage - carcinogenic
2 chemical preservatives added to commercially prepared foods
- calcium propionate
- sorbic acid
- sodium benzoate
- sodium nitrate (& nitrite)
why is chloramine considered more effective than chlorine for the disinfection of drinking water?
it’s more stable & doesn’t react with organic material (blood, vomit)
why would alcohol gel be preferred to antimicrobial soap for hand washing by healthcare professionals?
- no bacterial resistance
- quicker to use
- less drying than soap
- works well in presence of blood
cresol
a phenolic from the greasewood bush used to prevent the rotting of wooden posts, fences, railroad ties, etc.
hexachlorophene
a chlorinated phenol; used in soaps & lotions (Physohex); now known to increase risk of brain damage in babies
iodophor
a halogen; a mixture of iodine & surfactants; used for surgical scrubs and to disinfect skin before surgery
ethanol
an alcohol; widely used as skin antiseptic; a 50-70% solution in water is the most effective
soaps/detergents
surfactants
wash away microbes, but don’t kill them
hydrogen peroxide
used as an antiseptic & disinfectant
bubbles when it comes in contact with tissue
iodine tincture
a halogen
a mixture of iodine & alcohol
used as an antiseptic
formalin
alkylating agent
used to preserve tissues & to embalm
low concentrations are used to inactivate microbes for vaccines
chlorine (Chlorox)
a halogen
household bleach
added to drinking water & swimming pools
lysol
a phenolic
common ingredient in household & hospital disinfectants
remains active in the presence of blood & feces
ethylene oxide
alkylating agent
gas
used to sterilize heat sensitive materials
toxic to humans
silver nitrate
heavy metal
applied to newborn’s eyes to prevent gonorrhea
merthiolate
heavy metal containing mercury
antiseptic
basic first aid kit supplies
contains thimerosal
quats
surfactant
widely used as antiseptic for skin, mucous membranes & wounds; preop prep of skin, surgeon’s hands/arms
don’t kill spores
effectiveness decreased in presence of soap
supports Pseudomonas growth
wetting agent
a surfactant added to another chemical agent to help them penetrate fatty substances
selenium sulfide
heavy metal used to treat fungal skin infections
included in dandruff shampoos
crystal violet
also known as gentian violet; blocks cell wall synthesis inhibits G(+) bacteria & yeasts
betadine/isodine
a halogen
a mixture of iodine & surfactants
used for surgical scubs & to disinfect skin before surgery
zephiran/cepacol/bactine
surfactant
widely used
effectiveness decreased in presence of soap
supports Pseudomonas growth
triclosan
phenol used in many antibacterial soaps & cutting boards
chlorhexidine
biguanide
used in mouthwashes, surgical hand scrubs, skin creams
to teat gum disease (Peridex, Perioguard, Periochip)
interferes with Vit. K absorption
teeth staining occurs when taking iron
chloramines
now used by water treatment facilities to disinfect drinking water
copper sulfate
heavy metal used as a fungicide on crops & produce;
used as an algaecide & a molluscicide
sodium nitrate
prevents germination of Clostridium botulinum spores in meats
mercurochrome
heavy metal containing mercury antiseptic "monkey blood" now banned by FDA now contain quits instead
thimerosal
heavy metal containing mercury
found in merthiolate
also used as a vaccine preservative & in cosmetics, nasal sprays, etc.
povidone-iodine (PVP iodine)
a halogen
mixture of iodine & surfactants
used for surgical scrubs and to disinfect skin before surgery
PCMX (nanotechnology)
charged nano spheres of oil droplets
disrupt cell envelope
What are advantages of using PCMX (nanotechnology)
non-corrosive
non-irritating
kills quickly
doesn’t require EPA handling, warning or precaution
works well as Quats & chlorine-based products
