Sterilization and Disinfection

STERILIZATION

STERILIZATION

refers to the destruction of all forms of life, including bacterial spores.

This was when Joseph Lister introduced the concept of aseptic surgery and during that time he used carbolic acid (now it's called phenol)

DISINFECTION

refers to a process that eliminates a defined scope of microorganisms, including some spores

Physical or chemical methods may be used, but most disinfectants are chemical agents applied to inanimate objects.

ANTISEPTIC

substance applied to the skin for the purpose of eliminating or reducing the number of bacteria present

↪ do not kill spores and cannot be used as disinfectants

↪ Agent or substances that destroys or inhibits the growth of microorganisms

(FACTORS THAT AFFECT THE DEGREE OF KILLING OF MICROORGANISMS)

Spore forming bacteria

pores are coated with proteins, lipids, and carbohydrates as well as dipicolinic acid and calcium ↪ able to resists heat, chemical means or other methods

(FACTORS THAT AFFECT THE DEGREE OF KILLING OF MICROORGANISMS)

Mycobacterium spp.

cell wall is high in lipid contents which enables them to become resistant to most environmental stress such as desiccation

(FACTORS THAT AFFECT THE DEGREE OF KILLING OF MICROORGANISMS)

Biofilm forming bacteria

certain bacteria can aggregate into communities of bacteria which makes then resistant to chemical and physical means of destruction

↪ microorganisms living together in community

(FACTORS THAT AFFECT THE DEGREE OF KILLING OF MICROORGANISMS)

Prions

naked pieces of proteins, similar to viruses but without the nucleic acid, that is most resistant to the action of heat, radiation, and chemicals.

↪ agents that are able to cause degenerative diseases of our nervous system

(FACTORS THAT AFFECT THE DEGREE OF KILLING OF MICROORGANISMS)

TYPES OF ORGANISMS

different organisms have varying ability in withstanding chemical and physical treatment due to the different biochemical composition of these organisms and various mechanisms that they use to protect themselves.

(FACTORS THAT AFFECT THE DEGREE OF KILLING OF MICROORGANISMS)

NUMBER OF ORGANISMS

this factor basically refers to the amount of organisms present in the object to be treated referred to as microbial load (bioburden).

(FACTORS THAT AFFECT THE DEGREE OF KILLING OF MICROORGANISMS)

CONCENTRATION OF DISINFECTING AGENT

The amount needed to destroy microorganisms varies based on the agent to be used. It is therefore important to follow the correct preparation and dilution as prescribed by the manufacturer.

(FACTORS THAT AFFECT THE DEGREE OF KILLING OF MICROORGANISMS)

PRESENCE OF ORGANIC MATERIAL

Blood, pus, and mucus are examples of organic materials that may prevent the full contact of the agent to the organisms, hence limiting its action. Example is bleach 1 │transcribed by plnvllrl (sodium hypochlorite) that is easily inactivated by organic material.

Dilute in 1:10 dilution

1 part of bleach and 9 parts of water

(FACTORS THAT AFFECT THE DEGREE OF KILLING OF MICROORGANISMS)

NATURE OF SURFACE TO BE DISINFECTED

Some instruments that we use in the laboratory sometimes are made up of biomaterial which exempts them to disinfection or sterilization due to possible damage. Example is endoscopic instruments which can’t be autoclaved.

(FACTORS THAT AFFECT THE DEGREE OF KILLING OF MICROORGANISMS)

CONTACT TIME

it is critical to observe proper ____________ of the agent and the object to be disinfected or sterilized.

In principle, ____________ may be affected by all previous factors already mentioned as well as temperature.

(FACTORS THAT AFFECT THE DEGREE OF KILLING OF MICROORGANISMS)

Room Temperature

(20ºC to 22ºC).

(FACTORS THAT AFFECT THE DEGREE OF KILLING OF MICROORGANISMS)

pH

the material to be treated and the agent itself. Manufacturers usually optimize this factor to achieve maximum activity.

(FACTORS THAT AFFECT THE DEGREE OF KILLING OF MICROORGANISMS)

BIOFILMS

(community of bacteria)

certain bacteria have the ability to form communities of layers of bacteria with protective shields which is called as ________.

(FACTORS THAT AFFECT THE DEGREE OF KILLING OF MICROORGANISMS)

COMPATIBILITY OF DISINFECTANTS

Some disinfectants may inactivate the action of another hence it is also important to consider the compatibility of the disinfectants

(METHODS OF STERILIZATION) PHYSICAL METHODS

MOIST HEAT

coagulation of bacterial proteins including bacterial enzymes heat is the simplest means of sterilizing material provided that the material would be resistant to heat damage

(METHODS OF STERILIZATION) PHYSICAL METHODS

Autoclave

operates based on the principle of steam under pressure usually na ginagamit sa microbiology na pangdisinfect ng glass petri dish, culture media

✧ STERILIZATION: 121°C for 15lbs/in² for 15 minutes ✧ DECONTAMINATION: 135°C for 30lbs/in² for 30 minutes

✧ Biological indicator: Bacillus stearothermophilus

(METHODS OF STERILIZATION) PHYSICAL METHODS

TYNDALLIZATION

fractional discontinuous sterilization

✧ effective indication: 100°C for 30-60 minutes

✧ Instrument: Arnold’s Sterilizer

(METHODS OF STERILIZATION) PHYSICAL METHODS

INSPISSATION

thickening through evaporation

✧ effective indication: 75-80°C for 2 hours

✧ instrument: _________

(METHODS OF STERILIZATION) PHYSICAL METHODS

DRY HEAT

oxidation of bacterial components

pwedeng gamitin as sterilizing agent although it requires longer exposure time and higher temperature than moist heat

(METHODS OF STERILIZATION) PHYSICAL METHODS

DIRECT FLAME

direct application of flame in aseptic technique

(METHODS OF STERILIZATION) PHYSICAL METHODS

DRY/HOT AIR OVEN

used in the sterilization of heat resistant materials

✧ effective indication: 160-180°C for 1.5 to 2 hours

✧ biological indicator: Bacillus subtilis var. niger

(METHODS OF STERILIZATION) PHYSICAL METHODS

INCINERATION

burns materials into ashes; used in the disposal of biological wastes

✧ effective indication: 870-980°C for 2 seconds

(METHODS OF STERILIZATION) PHYSICAL METHODS

IONIZING RADIATION

works by alkylation of nucleic acid of bacteria using high energy short wavelength deep penetrating gamma rays; used for heat sensitive materials

Usually used in medical field for sterilization of disposable supplies: syringe, catheter and gloves

✧ biological indicator: Bacillus pumilis

(METHODS OF STERILIZATION) PHYSICAL METHODS

FILTRATION

based on membrane gradient by differences in particle size; used for the sterilization of heat sensitive materials

(METHODS OF STERILIZATION) PHYSICAL METHODS

FILTRATION

Size of most bacteria, yeasts, and molds are retained but may allow passage of Pseudomonas- like organisms

0.45-0.80μm

(METHODS OF STERILIZATION) PHYSICAL METHODS

FILTRATION

Size of most used to filter Pseudomonaslike organisms; used for critical sterilization of parenteral solutions

0.22 μm

~~(~~METHODS OF STERILIZATION) PHYSICAL METHODS

FILTRATION

Size of most able to retain small viruses

0.01 μm

(METHODS OF STERILIZATION) PHYSICAL METHODS

HIGH EFFICIENCY PARTICULATE AIR FILTER (HEPA)

has a pore size of 0.3 μm; usually used in Biological Safety Cabinet (BSC) and rooms of immunocompromised patients

~~(~~METHODS OF STERILIZATION) CHEMICAL METHODS

PERACETIC ACID

for surgical instruments

~~(~~METHODS OF STERILIZATION) CHEMICAL METHODS

FORMALDEHYDE VAPOR/VAPOR PHASE H2O2

for HEPA filters and large spaces

~~(~~METHODS OF STERILIZATION) CHEMICAL METHODS

GLUTARALDEHYDE

for medical instruments (e.g. bronchoscopes, etc.) ginagamit as disinfectant, sterilization, and for preservation

~~(~~METHODS OF STERILIZATION) CHEMICAL METHODS

ETHYLENE OXIDE (ETO) GAS

The recommended concentration is 450 to 700 mg of ethylene oxide per liter of chamber space at 55°C to 60°C for 2 hours.

✧ This method is also used extensively by the manufacturing industry for the sterilization of low-cost thermoplastic products.

✧ biological indicator: Bacillus subtilis var. globijii

(METHODS OF DISINFECTION) PHYSICAL METHODS

BOILING

destroys vegetative cells of bacteria but not their spores

✧ Effective indication: 100°C for 15-30 minutes

(METHODS OF DISINFECTION) PHYSICAL METHODS

PASTEURIZATION

used for the preservation of alcoholic beverages such as beers, wines, and also dairy products such as milks and yogurt

(METHODS OF DISINFECTION) PHYSICAL METHODS

NON-IONIZING RADIATION

uses low energy long wavelength ultraviolet rays to disinfect heat sensitive materials as well as large spaces

(METHODS OF DISINFECTION) CHEMICAL METHODS

ALCOHOL (MOA)

dehydration, lipid dissolution, and protein denaturation 70% Alcohol not 90%:

(METHODS OF DISINFECTION) CHEMICAL METHODS

ALCOHOL (Minimum Contact Time)

1-2 minutes or until completely evaporated

(METHODS OF DISINFECTION) CHEMICAL METHODS

HALOGENS (MOA)

inhibits protein function and acts as strong oxidizing agents

(METHODS OF DISINFECTION) CHEMICAL METHODS

HALOGENS (Chloride (Cl) in NaOCl)

used as disinfecting agents in many laboratory and hospitals spaces, surfaces, and also in treating water for portability Iodine (I2) in Betadine used as a household antiseptics and surgical antiseptics

(METHODS OF DISINFECTION) CHEMICAL METHODS

HEAVY METALS (MOA)

denaturation of enzymes and other essential bacterial proteins

(METHODS OF DISINFECTION) CHEMICAL METHODS

HEAVY METALS (Mercury )

active ingredient or merthiolate but this is already banned in the market due to its known toxicity

(METHODS OF DISINFECTION) CHEMICAL METHODS

HEAVY METALS (Copper )

CuSO4 crystals are used as algaecide in swimming pools and aquarium

(METHODS OF DISINFECTION) CHEMICAL METHODS

HEAVY METALS (Silver )

1%– used as prophylactic agent in Crede’s Prophylaxis in suspected cases of Ophthalmia neonatorum

(METHODS OF DISINFECTION) CHEMICAL METHODS

QUATERNARY AMMONIUM COMPOUNDS (QUATS) (MOA)

enzyme inhibition, protein denaturation, and disruption of plasma membrane

(METHODS OF DISINFECTION) CHEMICAL METHODS

QUATERNARY AMMONIUM COMPOUNDS (QUATS) (Zephiran)

Benzalkonium chloride

(METHODS OF DISINFECTION) CHEMICAL METHODS

QUATERNARY AMMONIUM COMPOUNDS (QUATS) (Cepacol)

Cetylpyridinium chloride

(METHODS OF DISINFECTION) CHEMICAL METHODS

PHENOL/PHENOLIC COMPOUNDS/BISPHENOLS (MOA)

plasma membrane destruction and enzyme denaturation