F- MICROBIAL CONTROL Flashcards
TWO ways to control microbial growth?
physical and chemical methods
it involves the destruction or elimination of ALL microbes including, cells, spores and viruses
STERILIZATION
this is used today to eliminate pathogens from milk and most other beverages
PASTEURIZATION
The REDUCTION of microbial populations to level considered safe by public health standards
SANITIZATION
process by which MOST microbial forms in a non-living object are DESTROYED
DISINFECTION
use of chemical agents on living tissues (skin) to prevent the spread of microorganisms, either by inhibiting their growth or destroying them
ANTISEPSIS
Substance used to eliminate microorganisms in living tissue
ANTISEPTIC
agent used to eliminate pathogens in non-living entities
DISINFECTANT
AGENT THAT KILLS
“CIDE” EX FUNGICIDE
AGENT THAT INHIBITS GROWTH
“STATIC”, VIROSTATIC (INHIBITS)
term used to describe increase in number
GROWTH
give the PHYSICIAL methods used to destroy or control pathogens
- heat
- combination of heat and pressure
- desiccation
- radiation
- filtration
- refrigeration/ low temperature
this is a physical method of microbial control which is the most practical, efficient, and inexpensive method of sterilization
HEAT
what are the two factors that affect heat for sterilization
temperature and time
baking in a thermostatically controlled oven provides effective sterilization of metals, glassware, some powders, oils and waxes
DRY HEAT STERILIZATION (dry-heat baking)
160-165C for 2 hrs or 170-180C for 1 hr
Give one example of dry heat sterilization?
-flaming a wire inoculating loop in a Bunsen burner flame, or using an electrical heating device
heat applied in the presence of moisture, as in boiling or steaming, it is faster and more effective than dry heat and can be accomplished at a lower temperature.
MOIST HEAT STERILIZATION
what happens to proteins when moist heat occurs?
COAGULATE (turns semisolid)
uses steam under pressure to completely destroy all microbial life
AUTOCLAVE
what is the pressure used in an autoclave and at what temperature?
15 psi and 121.5C for 20 minutes
what is usually being sterilized when using an autoclave?
- culture media
- instruments
- dressings
- intravenous equipment
- applicators
- solutions
- syringes
- transfusion equipment
eliminate pathogenic microbes, lower microbial numbers, which prolongs milk’s good quality under refrigeration
PASTEURIZATION
what are the three methods of pasteurization?
UHT- ultra high temperature (we use high temperature 280 degrees for 4-5 seconds
HTST- HIGH TEMPERATURE SHORT TIME ( RAW MILK is heated at 161 degrees for 15 seconds then rapidly cooled)
LOW TEMPERATURE- (145degrees f for 30mins)
what are the TWO types of heat sterilization?
- heat (dry and moist)
- pasteurization (UHT, HTST, LT)
is used to sterilize heat-sensitive materials, such as some culture media, enzymes, vaccines and antibiotic solutions
FILTRATION
remove almost all microorganisms larger than about 0.3mm in diameter
HEPA FILTER
cellulose esters or plastic polymers, have become popular for industrial and laboratory use, these filters are only 1 mm thick
MEMBRANE FILTERS
What type of filter is equipped using a biosafety cabinet?
HEPA FILTER
metabolic rate of most microbes is so reduced that they cannot reproduce or synthesize toxins
LOW TEMPERATURES/ REFRIGERATION (ordinary refrigerators 0-7C)
this is the removal of water, microorganisms cannot grow or reproduce but can remain viable for years.
DESICCATION
use of high concentrations of salts and sugars to preserve food, based on the effects of _______.
OSMOTIC PRESSURE
HIGH CONCENTRATION OF THESE SUBSTANCES CREATE ______ THAT CAUSES WATER TO LEAVE THE MICROBIAL CELL
HYPERTONIC ENVIRONMENT
kills microorganisms which has two types, ionizing and non ionizing
RADIATION
(gamma rays, X rays, high-energy electron beams)- has a wavelength shorter than that of the other type, less than about 1 nm, therefore it carries much more energy.
IONIZING RADIATION
This type of radiation is more frequently used in laboratories has a longer wavelength, usually greater than about 1 nm. UV is an example.
NONIONZING RADIATION
What does UV light damage in an exposed cell?
DNA, it causes bonds to form adjacent pyrimidine bases
what is a major disadvantage of UV light as a disinfectant?
- radiation is not very penetrating, so the organisms to be killed must be directly exposed to the rays.
the principle effect of ____– is the ionization of water, which forms highly reactive hydroxyl radicals. These radicals react with organic cellular components especially DNA.
RADIATION. used to sterilize pharmaceuticals, disposable dental and medical supplies. placed inside a UV cabinet
used in teaching laboratories to evaluate the efficacy of a chemical agent
DISK-DIFFUSION METHOD
what do you call the halo or circle on the outside of the disk that is used to indicate the efficacy?
ZONE OF INHIBITION (the bigger the zone the more effective)
the first person to use phenol (carbolic acid) to control surgical infections in the operating room.
Joseph Lister
often used in throat lozenges for its local anesthetic effect but has little antimicrobial effect at low concentrations. It is however disagreeable in odor and it can irritate the skin as such it is now rarely used as an antiseptic
PHENOL
derivative of phenol
PHENOLICS
exert antimicrobial activity by injuring lipid-containing plasma membranes, which results in leakage of cellular contents
PHENOLICS
what is the main ingredient of Lysol?
O-phenylphenol
derivative of phenol that contain TWO phenolic groups connected by a bridge
BISPHENOLS (bis indicates TWO)
name an ingredient used in prescription lotion, used for surgical and hospital microbial control procedures
and name an ingredient in antibacterial soaps which inhibits an enzyme needed for biosynthesis of fatty acids
HEXACHLOROPHENE
TRICLOSAN
this disinfectant has broad spectrum of activity with mode of action primarily affecting BACTERIAL CELL MEMBRANES. It is not sporicidal but have some activity against enveloped viruses
BIGUANIDES
frequently used for microbial control on skin and mucous membranes. Combined with a detergent or alcohol it is very often used for surgical hand scrubs and preoperative skin preparation in patients
CHLORHEXIDINE a type of biguanide
-ALSO a component of mouthwash (oral cavity)
gargle is not the same (it involves air)
particularly iodine and chlorine, effective antimicrobial agents, both alone and as constituents of inorganic or organic compounds
HALOGENS
one of the oldest and most effective antiseptics, it impairs protein synthesis and alters cell membranes, apparently by forming complexes with amino acids and unsaturated fatty acid.
(I2) IODINE
widely used disinfectant, germicidal action is caused by the hypochlorous acid. Prevents much of the cellular enzyme system from functioning
CHLORINE (Cl2)
what is formed when bleach/chlorine is added to water?
HYDROCHLOROUS ACID
Combination of iodine and an organic molecule from which iodine is released slowly
IODOPHORS- have antimicrobial activity of iodine but they do not stain and are less irritating.
*betadine- the most common commercial preparation
effectively kill bacteria and fungi but not endospores and non-enveloped viruses. Mechanism of action is usually protein denaturation, can also disrupt membranes and dissolve many lipid
ALCOHOLS
-it can be both antiseptic and disinfectant
what are the two most common forms of alcohol?
- ethanol
- isopropanol
what is the recommended optimum concentration of ethanol?
70%
this is often sold as rubbing alcohol, is slightly superior to ethanol as an antiseptic and disinfectant
ISOPROPANOL
among the two alcohols which is more drying?
-both ethanol and isopropyl alcohol are similar in function and structure BUT ethanol is capable of drying out the skin if used without additional agents. Because of this isopropyl is a better solution and more often used as an antiseptic.
- eth dries tissue faster
- iso has more carbon atoms making it more effective
they are able to exert antimicrobial activity through oligodynamic action
HEAVY METALS AND THEIR COMPOUNDS (SILVER AND COPPER)
heavy metal contains antimicrobial activity even in very small amounts
OLIGODYNAMIC ACTION
this is what you call the antimicrobial property done by heavy metals
oligodynamic property
what solution is used for ophthalmia neonatorum (crede’s prophylaxis)? (babies born from gonorrhea mothers/std)
1% silver nitrate solution (silver)
*erythromycin cream is more commonly used this day,
topical cream used on burns
SILVERSULFADIAZINE
new antimicrobial for application to surfaces, contains water-insoluble silver iodide
SURFACINE
Used chiefly to destroy green algae (algicide) that grow in reservoirs, stock ponds, swimming pools, and fish tanks
COPPER SULFATE
common ingredient in mouthwashes
ZINC CHLORIDE
an ingredient in antidandruff shampoo
ZINC PYRITHIONE
decrease surface tension among molecules of a liquid. Such agents include soaps and detergents
SURFACE-ACTIVE AGENTS
these have little value as an antiseptic, but it does have an important function in the mechanical removal of microbes through scrubbing
SOAPS AND DETERGENTS
soaps breaks the oily film into tiny droplets, what is this process called?
EMULSIFICATION
most widely used surface-active agents, strongly bactericidal against gram-positive bacteria and less active against gram-negative bacteria. it is fungicidal, amoebicidal, and virucidal against enveloped viruses.
Chemical mode of action is unknown but probably affect plasma membrane.
QUATERNARY AMMONIUM COMPOUNDS (QUATS)
a popular quats:
-benzalkonium chloride (zephiran) used for cleaning the cuticles
these are used to preserve or lengthen food shelf-life
CHEMICAL FOOD PRESERVATIVES
disinfectant used in wine-making
SULFUR DIOXIDE
prevents molds from growing in certain acidic foods such as cheese and soft drinks
sorbic acid,
potassium sorbate
sodium benzoate
antifungal antibiotic approved use in foods, mostly cheese
NATAMYCIN (PRIMARICIN)
They inactivate proteins by forming covalent cross-links with several organic functional groups on proteins
ALDEHYDE
available as formalin, 37% aqueous solution, used to preserve biological specimens
FORMALDEHYDE
Less irritating and more effective than formaldehyde. used to disinfect hospital instruments, including endoscopes and RT equipment but they must be cleaned carefully.
GLUTARALDEHYDE
these are gases used to sterilize an area
CHEMICAL STERILIZATION
ethylene oxide- kills all microbes and endospores but requires a lengthy exposure period of several hours
chlorine dioxide- used to fumigate enclosed building area
group of oxidizing agents that include hydrogen peroxide and peraceetic acid
PEROXYGENS
effectively disinfect inanimate objects it is even sporicidal at high concentrations
HYDROGEN PEROXIDE
ONE OF THE MOST EFFECTIVE LIQUID CHEMICAL SPORICIES AVAILABLE AND CAN BE USED AS A STERILANT
PERACETIC ACID
