[1S] UNIT 1.2 Control of Microbial Growth Flashcards by JULIA CASSANDRA RECCION

Q

TYPE OF ORGANISM

T/F: The ability of the microorganism to withstand the different disinfecting / sterilizing agents depend on the chemical composition and protective mechanisms inherent to such microorganism.

A

T

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Q

Are produced by some bacteria to confer resistance to heat, radiation, and other harsh environmental conditions.

A

Endospores

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Q

TYPE OF ORGANISM

T/F: Some bacteria form biofilms that protect them from radiation, desiccation, high pressure, extreme pH temperature, and antimicrobial agents

A

T

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Q

Refers to the number of microorganisms present in the specimen/object.

A

Microbial Load

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Q

CONCENTRATION OF THE AGENT TO BE USED

T/F: Less concentrated disinfectants are effective in microbial inhibition or killing.

A

F; More concentrated

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Q

PRESENCE OF ORGANIC MATERIAL

T/F: Presence of mucus, blood, and pus can inactivate the disinfecting agent by preventing the full contact of the agent and the material to be disinfected.

A

T

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Q

PRESENCE OF ORGANIC MATERIAL

Examples of chemical agents that can be inactivated include bleach and ______.

A

Quaternary Ammonium Compound (QUATS)

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Q

NATURE OF SURFACE TO BE DISINFECTED

Devised a logical approach for disinfection/sterilization of inanimate objects or surfaces based on the degree of risk involved in their use.

A

Earle Splaulding

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Q

NATURE OF SURFACE TO BE DISINFECTED

According to Spaulding classification, equipment/items are regarded as: _______, ___________, __________.

A

Critical
Semi-critical
Non-critical

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Q

NATURE OF SURFACE TO BE DISINFECTED

Are devices that enter sterile body parts, including the vascular system

A

Critical Items

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Q

NATURE OF SURFACE TO BE DISINFECTED

Are devices that enter sterile body parts, including the vascular system

A

Critical Items

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Q

NATURE OF SURFACE TO BE DISINFECTED

Are those that come in contact with non-intact skin or mucous membrane but does not penetrate them

A

Semi-critical Items

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Q

NATURE OF SURFACE TO BE DISINFECTED

T/F: High level of disinfection is required for the critical items, while low level of disinfection is implemented for non-critical items

A

T

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Q

NATURE OF SURFACE TO BE DISINFECTED

Touches only the intact skin but not the mucous membrane

A

Non-critical Items

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Q

Refers to the length of time a chemical agents needs to stay on a targeted surface in order to become an effective disinfectant/sterilant

A

Contact Time

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Q

CONTACT TIME

T/F: Applying the chemical agent and wiping it immediately may render it useless in killing or inhibiting growth microorganisms

A

T

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Q

TEMPERATURE & PH

T/F: Most disinfectants are effective at room temperature under a basic condition

A

F; acidic condition

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Q

TEMPERATURE & PH

T/F: Disinfection can be enhanced by an increase in temperature only up to a certain degree

A

T

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Q

TEMPERATURE & PH

T/F: Too much increase in temperature may affect the efficacy of a disinfectant and therefore strengthen its germicidal activity

A

F; weaken

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Q

TEMPERATURE & PH

T/F: In chlorination, as pH goes up, the concentration of hypochlorite ions decreases and disinfection becomes less effective

A

F; increases

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Q

COMPATIBILITY OF DISINFECTANTS

T/F: QUATS and bleach should not be used together. Mixing it may result in a creation of toxic gas

A

T

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Q

What are the factors affecting microbial growth?

A

● Type of Organism
● Microbial Load
● Concentration of Agent to be used
● Presence of Organic Material
● Nature of surface to be disinfected
● Contact time
● Temperature
● pH
● Compatibility of disinfectants

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Q

refers to methods employed to prevent entry of organisms into the body as well into test tubes, flasks or plates used in microbial cultivation

A

Aseptic Technique

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Q

refers to the absence of microbes in an area or object

A

Asepsis

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a condition in which microbial growth and multiplication is halted or inhibited. The microorganism is not killed or destroyed in the process. Include the use of refrigeration as well as dyes.

Bacteriostasis

involves chemical disinfection of living tissues (i.e. mucus membrane, skin) as well as in the treatment of wounds. The chemical agent employed is called an _______

antiseptic / Antisepsis

T/F: In bacteriostasis, the microorganism is not killed or destroyed in the process.

T

are chemical sterilants used to destroy all forms of life. It is also known as chemical sterilants

Biocide

microorganisms inadvertently introduced to specimens or bacterial culture

Contaminant

the process of removal of pathogenic microorganisms so materials/items are safe to handle or dispose.

Decontamination

removal of transient microorganisms from the skin using mechanical cleansing or antiseptics.

Degerming

process of destruction of pathogenic microorganisms except spores, prions and other microorganisms.

Disinfection

reduction of pathogens on eating utensils to safe public health levels by mechanical cleansing or use of chemicals.

Sanitization

destruction of all forms of life including bacterial spores.

Sterilization

lowest temperature in which all bacteria in a liquid culture will be killed in 10 minutes 1

Thermal Death Point

minimal length of time in which all bacteria in a liquid suspension will be killed at a given temperature

Thermal Death Time

FACTORS THAT IMPACT THE EFFECTIVENESS OF DISINFECTANTS CONSIDERATION: Some surfaces or materials may be damaged. Many medical instruments are damaged by eat or corrosive materials

Surface or material to be disinfected

FACTORS THAT IMPACT THE EFFECTIVENESS OF DISINFECTANTS CONSIDERATION: Excess dirt, blood, mucus, or pus may inactivate the agent; it may be necessary to clean the surface prior to disinfection

Presence of organic material

FACTORS THAT IMPACT THE EFFECTIVENESS OF DISINFECTANTS CONSIDERATION: The amount of time the disinfectant is in contact with the surface affects the amount of organism destruction. Betadine must have a contact time of ______ minutes in order to kill microorganisms

1 to 2

FACTORS THAT IMPACT THE EFFECTIVENESS OF DISINFECTANTS CONSIDERATION: Different type of microorganism may be more resistant to the effects of certain disinfectants. Spores, mycobacteria, prions, and biofilms may require specific agents

Organism Type

● Most commonly used method ● Cheap, economical and reliable ● It could either be through MOIST HEAT or DRY HEAT

Heat

FACTORS THAT IMPACT THE EFFECTIVENESS OF DISINFECTANTS CONSIDERATION: The amount and concentration of disinfectant required to adequately destory microorganism vary by product. Manufacturer instructions regarding preparation and use should always be followed.

Concentration of disinfectant

FACTORS THAT IMPACT THE EFFECTIVENESS OF DISINFECTANTS CONSIDERATION: The presence of greater amounts of microorganism usually requires greater contact time with the disinfectant

Amount of organism present

FACTORS THAT IMPACT THE EFFECTIVENESS OF DISINFECTANTS CONSIDERATION: Temperature and pH can alter activity. Most disinfectant require increased contact time in colder temperatures. The pH of the material to be disinfected must be considered, as some disinfectants are only active within a certain range.

Temperature and pH

2 Sterilization Methods

● Physical Means ● Chemical Means

Principle of dry heat

Oxidation

Longer Exposure time and higher temperatures

Dry Heat

For the sterilization of inoculating loops, needles, mouth of tubes

Open Flame

DRY HEAT ● HOT AIR OVEN: ● TEMPT REQUIREMENTS:

Sterilize Glasswares 160-180C for 1.5-3 hours

OPEN FLAME BUNSEN BURNER:

Flame Sterilization

● For disposal of hospital waste (infectious) ● Now Outlawed: RA 8749 Clean Air Act of 1999

Incineration

T/F: In moist heat, all microorganisms are killed except prions

T

● Or HEAT UNDER STEAM PRESSURE ● More effective than dry heat ● Shorter time of exposure ● Sterilization method of choice for heat stable objects

Moist Heat

MOIST HEAT PRINCIPLE: AUTOCLAVE:

Coagulation of Proteins 121C, 15psi (1atm) for 15 minutes

● Form of disinfection; DOESN’T KILL SPORES ● 100C for 10-15 minutes

Boiling

eliminates food borne pathogens responsible for food spoilage

Pasteurization

PASTEURIZATION METHODS 1. Batch Method: 2. Flash Method 3. High Tempt Short Time

1. 63C for 30minutes 2. 72C for 15seconds 3. 72C-140C then 72C for <5sec

● Flowing Steam ● Fractional ● Intermittent ● 100C for 30 mins for 3 days ● Arnold’s Sterilizer

Tyndallization

● for sterilization of high protein media ● 75-80C for 2hrs on 3 consecutive days

Inspissation

TYPE OF MOIST HEAT: Steam Under Pressure APPARATUS EMPLOYED: Gravity Displacement TEMPERATURE: 121C @ 15psi (1 atm) TIME: 15-20 minutes APPLICATION: ?

Sterilization of Culture Media

TYPE OF MOIST HEAT: Steam Under Pressure APPARATUS EMPLOYED: Gravity Displacement TEMPERATURE: 121C @ 15psi (1 atm) TIME: ? APPLICATION: Biological waste in broth or solid media

30 minutes

TYPE OF MOIST HEAT: Steam Under Pressure APPARATUS EMPLOYED: Vacuum Autoclave TEMPERATURE: 132 @ 15psi (1 atm) TIME: ? APPLICATION: Biological waste in broth or solid media

4 minutes

TYPE OF MOIST HEAT: Steam Under Pressure APPARATUS EMPLOYED: Vacuum Autoclave TEMPERATURE: 132 @ 15psi (1 atm) TIME: 30-60 minutes APPLICATION: ?

Biologic waste (blood/body fluids)

TYPE OF MOIST HEAT: ? APPARATUS EMPLOYED: Arnold’s Sterilizer TEMP: 100C TIME: 30 mins for 3 consecutive days with incubation period in between sterilization APPLICATION: Heat sensitive media that cannot withstand autoclave temperature

Tyndallization

TYPE OF MOIST HEAT: ? APPARATUS EMPLOYED: Inspissator TEMP: 75-80C TIME: 2 hours for 3 successive days APPLICATION: High protein media

Inspissation

TYPE OF DRY HEAT: Incineration APPARATUS EMPLOYED: ? TEMP: 870-980C TIME: - APPLICATION: Safest method to destroy all microorganisms including prions; applicable for disposal of carcasses and medical wastes

Incinerator

TYPE OF DRY HEAT: ? APPARATUS EMPLOYED: Dry heat oven TEMP: 160-180C / 121C TIME: 1.5-3 hrs / 16 hrs APPLICATION: For glassware, oils, petroleum, powder

Hot Air Sterilization

TYPE OF DRY HEAT: ? APPARATUS EMPLOYED: Bunsen burner or alcohol lamp / Bacti-cinerator sterilizer TEMP: - / approx. 815.6C TIME: until red hot (for loop & needle) APPLICATION: Sterilization of inoculation needle, loops, tips of metal forceps

Direct Flaming

Separation of bacteria from liquids or air

Filtration

FILTRATION OF LIQUIDS: through Berkefeld

diatomaceous earth

FILTRATION OF LIQUIDS: through ○ Morton: _____ ______ ○ Seitz: ______ ____

sintered glass asbestos pad

FILTRATION OF LIQUIDS: through ○ Chamberland-Pasteur: ______ _____ ○ Membrane Filters: ________ _____

unglazed porcelain Cellulose esters

For critical sterilization: ______ filter must be used

0.22um

FILTRATION OF AIR through: ? ○ able to remove organisms >0.3um ○ Uses: Laboratory hoods, rooms of immunodeficient patients

HEPA (High Efficiency Particulate Air Filters)

MOA: alkylation of Nucleic acid

Radiation

● Gamma rays or electron beams ● Short wavelength but high energy ● USE: Sterilization of disposable materials in the medical industry

Ionizing Radiation

● UV rays ● Long wavelength but low energy ● Poor penetration ● USE: disinfection of surfaces

Non-ionizing

PHYSICAL METHODS ● dehydration ● removal of water to stop metabolic action of bacteria

Dessication

PHYSICAL METHODS ○ through PLASMOLYSIS ○ high concentrations of sugar/salt

High Osmotic Pressure

PHYSICAL METHODS ○ bacteriostatic

Exposure to Low Temperature

CHEMICAL METHODS ○ cold sterilization ○ gas chamber (450-700 mg/L), 55-60C ○ minimum time: 2hours ○ Principle: Alkylation of nucleic acids

GASEOUS CHEMICALS: ETHYLENE OXIDE

CHEMICAL METHODS ○ shorter contact time of killing

GASEOUS CHEMICALS: Hydrogen Peroxide and Periacetic Acid

CHEMICAL METHODS ○ Mode of Action: Protein Denaturation and Lipid Dissolution ○ 70% ETHANOL

Alcohols

CHEMICAL METHODS Mode of Action: Alkylation of Nucleic Acids and Protein Denaturation ■ 2% GLUTARALDEHYDE: disinfectant ■ 40% FORMALIN

Aldehydes

CHEMICAL METHODS ○ Mode of Action: Cytoplasmic Membrane Destruction ○ Uses: Commonly used antiseptic in surgery

Chlorhexidine

CHEMICAL METHODS ● Mode of Action: Oxidation of cellular Components and Protein Denaturation ● Iodine

Halogens

HALOGENS alcohol and iodine solutions for antiseptics

Tincture

HALOGENS ● iodine plus a neutral polymer carrier ● must be diluted ● Preferrable ● ex. POVIDONE-IODINE (“BETADINE”)

Iodophors

HALOGENS ■ one of the oldest and common disinfectants ■ In the form of : HYPOCHLORITE ● not used as sterilants ■ Dilution: 1:10 dilution of 5.25%

Chlorine

CHEMICAL METHODS: WATER STERILIZATION Bleach:Water

2-3 drops bleach in 1 L of water for 30 minutes

CHEMICAL METHODS: WATER STERILIZATION Addition of Chlorine in swimming pools and in drinking water

Copper Sulfate Pentahydrate

CHEMICAL METHODS: WATER STERILIZATION Collection for Water Testing

Add Sodium Thiosulfate

CHEMICAL METHODS ○ Rarely used, bacteriostatic ○ Mode of Action: protein and enzyme inactivation

Heavy Metals

CHEMICAL METHODS: HEAVY METALS ■ Mercury: ? ■ Silver: ? (Crede’s Prophylaxis) ■ Copper: ? – anti-algae

Merthiolate 1% Silver Nitrate Copper Sulfate

CHEMICAL METHODS Mode of Action: oxidation of cellular components ■ Hydrogen peroxide ■ Ozone

Oxidizing Agents

CHEMICAL METHODS ○ Mode of Action: Protein denaturation, cell membrane andenzyme inactivation ○ Chemically substituted phenol compounds ○ Less toxic and more effective ■ Examples: ortho-phenylphenol and ortho-benzyl-para-chlorophenol ■ Uses: Hospital and institutional disinfection

Phenolic Compounds

CHEMICAL METHODS ○ Mode of Action: Protein denaturation, cell membrane andenzyme inactivation ○ Chemically substituted phenol compounds ○ Less toxic and more effective ■ Examples: ortho-phenylphenol and ortho-benzyl-para-chlorophenol ■ Uses: Hospital and institutional disinfection

Phenolic Compounds

CHEMICAL METHODS Mode of Action: interruption of electron transport, enzyme inhibition and membrane destruction

Hexachlorophene

CHEMICAL METHODS ○ Effective against Gr (+) ○ Residual effect ○ TOXIC

Hexachlorophene

CHEMICAL METHODS ○ Mode of Action: cell wall disruption and enzyme inactivation ○ Effective against Gr (+) ○ Not affected by organic compunds

Chloroxylenol

● Mode of Action: protein denaturation and cell membrane destruction ● surface active agents; reduce surface tension ● inactivated by organic compounds and hard water (ex. Benzalkonium Cl (Zephiran), Cetylperidium Chloride) ○ Resistant to M. tuberculosis

QUATS

● Mechanical Action by rubbing and scrubbing ○ Possess antibacterial ingredients such as triclocarbon or triclosan

Soaps & Detergents

How to check the effectiveness of physical methods?

Through the use of spore strips & determination of phenol coefficient

EFFECTIVENESS OF PHYSICAL METHODS Bacillus subtilis var. niger

HOT-AIR OVEN

EFFECTIVENESS OF PHYSICAL METHODS Bacillus subtilis var. globigii

Ethylene Gas

EFFECTIVENESS OF PHYSICAL METHODS Bacillus pumilus

Ionizing Radiation

EFFECTIVENESS OF PHYSICAL METHODS Bacillus stearothermophilus

Autoclave