(Lecture) Sterilization and Disinfection Flashcards by SHEKINAH MOLO

Q

Destruction of all forms of microbial life including spores.

A

Sterilization

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Q

Destruction of microbes that cause disease; may not be effective in killing spores.

A

Disinfection

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Q

Destruction or inhibition of microorganisms in living tissue thereby limiting or preventing the harmful effect of infection.

A

Antisepsis

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Q

Methods of Microbial Control are divided into two groups. What are the two groups?

A

Chemical Methods of Sterilization and Disinfection
Physical Methods of Sterilization and Disinfection

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Q

Destroys only a define scope of microorganisms including some spores but not necessarily all microbial life.

A

Disinfection

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Q

Term used when the agent is applied to the skin or living tissue for the purpose of limiting the number of bacteria present.

A

Antisepsis

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Q

Chemical agents used for antisepsis are called _____

A

Antiseptics

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Q

Used in microbiological research, the preservation of food and the prevention of the disease.

A

Aseptic Techniques

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Q

Laboratory work with pure cultures requires the use of _____ and _____

A

Sterile Apparatus
Culture Media

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Q

Chemical Agents are used mainly for _____ and Physical Methods are used mainly for _____

A

Disinfection
Sterilization

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Q

List down the types of Physical Agents:

A

Sunlight
Drying
Heat
Filtration
Radiation
Ultrasonic and Sonic Vibrations

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Q

Two types of Heat under Physical Agent category:

A

Dry Heat
Moist Heat

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Q

List down all the divisions under Chemical Agents (excluding the subdivisions):

A

Agents that damage the cell membrane
Agents that damage proteins
Agents that modify functional groups of proteins and nucleic acids

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Q

Identify under what category is this under Chemical Agents:

Surface-active Disinfectants

A

Agents that damage the cell membrane

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Q

Identify under what category is this under Chemical Agents:

Phenols

A

Agents that damage the cell membrane

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Q

Identify under what category is this under Chemical Agents:

Phenolic Compounds

A

Agents that damage the cell membrane

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Q

Identify under what category is this under Chemical Agents:

Acids and Alkalines

A

Agents that damage/denature proteins

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Q

Identify under what category is this under Chemical Agents:

Heavy Metals

A

Agents that modify functional groups of proteins and nucleic acids

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Q

Identify under what category is this under Chemical Agents:

Oxidizing Agents

A

Agents that modify functional groups of proteins and nucleic acids

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Q

Identify under what category is this under Chemical Agents:

Dyes

A

Agents that modify functional groups of proteins and nucleic acids

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Q

Identify under what category is this under Chemical Agents:

Alkylating Agents

A

Agents that modify functional groups of proteins and nucleic acids

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Q

List down the Mode of Action of some chemical agents:

A

Reaction with the bacterial plasma membrane
Denaturation or coagulation of bacterial proteins
Reaction with enzymes
Damage to nucleic acids

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Q

Two types of Surface Active Agents

A

Cationic Agents
Anionic Agents

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Q

Quaternary Ammonium Compounds or Quates is what type of Surface Active Agents?

A

Cationic Agents

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Identify what type of Surface Active Agents based on the description: * Causes loss of cell membrane semi permeability leading to loss of nutrients and essential metabolites. * Denatures protein

Cationic Agents

Soaps and Fatty Acids are what type of Surface Active Agents?

Anionic Agents

Identify what type of Surface Active Agents based on the description: * Causes gross disruption of cell membrane lipoprotein framework. * More active in Gram-positive bacteria than in Gram-negative bacteria. * Active at acidic pH.

Anionic Agents

● Highly effective in Gram-positive bacteria. ● Clinically not used because of its neurotoxic effect. ● Currently used as a standard for measuring bactericidal potency of new chemicals.

Phenolic Compounds

This is the ratio of the concentration of the new chemical agent being tested to the concentration of the reference standard (phenol) required to kill in a specific time.

Phenol Coefficient

If phenol coefficient is <1, the new chemical agent is _____ than phenol.

Less Effective

If phenol coefficient is =1, the new chemical agent is _____ to phenol in efficacy.

Equal

If phenol coefficient is >1, the new chemical agent is _____ than phenol.

More Effective

Uses of Organic Solvents:

1. Potent skin disinfectants 2. Disinfects clinical thermometer

Ethanol is potents at concentration of _____

70%

○ Disorganize cell membrane lipid structure ○ Denatures protein ○ Active against Gram-positive bacteria, Gram-negative bacteria, and acid-fast bacili.

Alcohol

● Causes conformational alteration of proteins (unfolding of polypeptide chain) resulting in irregular looping and coiling of polypeptide chain.

Acids and Alkalies

Acids like _____, _____, and _____ are helpful as food preservatives: extending storage life of food products

Benzoic Acids Citric Acid Acetic Acid

A type of mercurials that has a limited use because of its toxicity

Mercuric Chloride

A type of mercurials that is less toxic than inorganic mercuric salts

Organis Mercurials

Use of Mercurials

As antiseptics

Use of Silver Compounds

As ophthalmic and wound antiseptic

Converts functional -SH group into non-functional -S-S group

Oxidizing Agents

This is a Halogen that is inactivated by organic materials

Chlorine

This is a Halogen that is an effective skin disinfectant

Iodine

An example of Oxidizing Agent that is used for cleansing of wound, disinfecting medical-surgical devices, and plastic contact lenses

3% Hydrogen Peroxide

Give examples of Dyes

Brilliant Green Malachite Green Crystal Violet

Uses of Dyes:

1. For treatment of dermatological lesions 2. For formulation of selective culture media

Examples of Alkylating Agents:

1. Formaldehyde 2. Glutaraldehyde 3. Ethylene Oxide

Formaldehyde's 37% aqueous solution form is named as _____

Formalin

Uses of Formaldehyde:

1. Preservation of fresh tissues 2. Preparation of vaccines from bacterial surfaces, viruses, and toxins 3. Bactericidal including spores

Gaseous sterling chemical

Ethylene Oxide

Use of Ethylene Oxide

Sterilize medical-surgical devices that would be damaged by heat

This are disinfectants that are applied on animate bodies

Antiseptic Agents

Characteristics of Antiseptic Agents:

● Never toxic to cells ● Never be corrosive ● Should never change nature of skin

The most reliable and universally applicable Method of Sterilization

Heat

List down the Mechanism of Action of Heat:

1. Dry Heat 2. Moist Heat

A Mechanism of Action of Heat that denatures protein

Dry Heat

Mechanism of Action of Heat that is used in scalpels and neck of flasks, bottles, and tubes are exposed for a few seconds, but it is of uncertain efficacy

Flaming

Hot Air Sterilizer or Oven is done by applying _____ to _____ degree Celsius for _____ to _____ hours

160-180 degree Celsius 1.5-3 Hours

Sterilizes glassware, oils, greases, lubricants, and powders

Hot Air Sterilizer (Oven)

Not reliable method of heat sterilization

Boiling

Boiling is done by applying _____ for _____

100 degree Celsius 15 minutes

Used for sterilizing catheters, dressing, and fabrics

Boiling

Intermittent steaming (fractional sterilization)

Tyndallization

Tyndallization is done at _____ for _____ on _____ days

100 degree Celsius 30 minutes 3 consecutive days

Used for sterilizing heat sensitive culture media containing materials such as carbohydrates, egg, or serum

Tyndallization

Preferred temperature and time for Holder Method of Pasteurization

63 degree Celsius for 30 minutes

Preferred temperature and time for Flash Method of Pasteurization

72 degree Celsius for 15 seconds

Used in the pasteurization of milk and preparation of bacterial vaccines

Pasteurization

* Steam under pressure * Based on the principle that when water is boil at increased pressure, hot saturated steam will be formed which penetrates and gives up its latent heat when it condenses on cooler objects.

Autoclaving

Hot saturated steam in Autoclaving acts as an excellent agent for sterilization because of:

1. High temperature 2. High latent heat 3. Ability to form water of condensation 4. Contraction in volume that occurs during condensation

Most culture media are sterilized at a pressure of _____, at a temperature of _____ for _____. It destroys bacterial endospores and vegetative cells.

15 lb/in 121 degree Celsius 15 minutes

Used to sterilize solid and fluid culture media, gowns, medical and surgical equipment.

Autoclaving

Methods of controlling Sterilization

● Recording of temperature and time of each sterilizing cycle. ● Heat sensitive autoclave tape fixed to the outside of each pack. ● Biological indicator

Color change of autoclave tape from blue to _____ indicates complete sterilization.

Brown-black

Color change of autoclave tape from _____ to brown-black indicates complete sterilization.

Blue

* Inactivation of living bacteria by cold. * It prevents active multiplication of bacteria by decreasing the metabolic activity of bacteria.

Freezing

Freeze-drying

Lyophilization

Involves rapid freezing with subsequent drying.

Lyophilization

Use of Lyophilization

1. Preservation of microbial cultures 2. Preservation of vaccines

Mechanical sieving through membrane filters.

Filtration

Uses of Filtration:

● Sterilization of thermolabile parental and ophthalmic solutions, sera, and plasma. ● Microbial evaluation of water purity. ● Determination of viral particle size.

Ion radiation includes:

X-ray Y-ray Beta-ray

This has has less quantum energy with low penetrating power than ionic radiation

Ultraviolet Radiation

Spore forming bacteria are more resistant to ionic and ultraviolet radiation than vegetative bacteria because of:

● The spore coat confers protection. ● DNA is in different state in spores.

Uses of Radiation:

● Sterilize surgical sutures, catheters, petri dishes, culture media while dispensing, and pharmaceutical products like hormones, enzymes, and antibiotics. ● It also sterilize biological safety cabinet (laboratory rooms).

Recommended concentration of Betadine (Iodophore)

2%

Recommended concentration of Bleaching Powder (Calcium Hypochlorite)

14g in 1L of water

Recommended concentration of Dettol (Chloroxylenol)

4%

Recommended concentration of Ethyl Alcohol

70%

Recommended concentration of Glutaraldehyde

2%

Recommended concentration of Lysol

2.5%

Recommended concentration of Savlon (Chlorhexidine and Cetrimide)

2%, 5%

Recommended concentration of Sodium hypochlorite

1%, 0.1%

Identify the Method of Sterilization or Disinfection used: Metallic inoculating loops or wires

Red heat

Identify the Method of Sterilization or Disinfection used: Infective materials like soiled dressings, bed

Burning (incineration)

Identify the Method of Sterilization or Disinfection used: Glasswares-syringes, petri dishes, test tubes, flasks, universal containers, oily fluids (paraffin)

Hot air oven or autoclave

Identify the Method of Sterilization or Disinfection used: Metal instruments

Autoclaving, hot air oven, infrared radiation

Identify the Method of Sterilization or Disinfection used: Serum, body fluids, bacterial vaccines

Waterbath at 56°C x 1 hour, vaccine bath at x 1hr

Identify the Method of Sterilization or Disinfection used: Gloves, aprons, dressings, catheters, surgical instruments except sharp instruments

Autoclaving

Identify the Method of Sterilization or Disinfection used: Sharp instruments

5% cresol

Identify the Method of Sterilization or Disinfection used: Suture materials except catgut

Autoclaving

Identify the Method of Sterilization or Disinfection used: Catgut

Ionizing radiation

Identify the Method of Sterilization or Disinfection used: Milk

Pasteurization

Identify the Method of Sterilization or Disinfection used: Most of the culture media

Autoclaving

Identify the Method of Sterilization or Disinfection used: Culture media containing egg serum or sugar

Tyndallization

Identify the Method of Sterilization or Disinfection used: Toxin, ascetic fluid, serum, sugar, and antibiotic solutions

Filtration

Identify the Method of Sterilization or Disinfection used: Rubber, plastic, and polythene tubes including disposable syringes

Gamma radiation, ethylene oxide gas

Identify the Method of Sterilization or Disinfection used: Faeces and urine, vomitus, sputum

Bleaching powder, cresols, formalin, burning, autoclaving

Identify the Method of Sterilization or Disinfection used: Disposable syringes, rubber or plastic disposable goods, bone and tissue grafts, adhesive dressings

Ionizing radiation

Identify the Method of Sterilization or Disinfection used: Antitoxic sera, serum, urine

Merthiolate (1 : 10,00)

Identify the Method of Sterilization or Disinfection used: Operation theatre, wards, and laboratory or floor space

* Formaldehyde gas and cresols (Lysol) * Sodium hypochlorite (1%)

Identify the Method of Sterilization or Disinfection used: Polythene tubing, fabrics, machine

Ethylene oxide

Identify the Method of Sterilization or Disinfection used: Water

Chlorine as hypochlorite (0.2%)

Identify the Method of Sterilization or Disinfection used: Skin

Tincture iodine, spirit (70% ethanol), savlon (phenol derivative)

Identify the Method of Sterilization or Disinfection used: Woollen blankets, wool and hides

Formaldehyde gas

Identify the Method of Sterilization or Disinfection used: Sterilization of operation theatre

Formaldehyde gas (50cc formalin and 25g KMnO per 100cu. ft. space)