sterilization refers to the destruction of all forms of life, including bacterial spores.
complete removal of microorganism
sterilization
Joseph lister introduced antiseptic surgery using carboxylical acid that is now call phenol
disinfection refers to a process that eliminates a defined scope of microorganism, including some spores
physical or chemical method may be used but most disinfectants are chemical agents applied to inanimate objects
disinfection only reduces the number of microorganism not removing them completely
antiseptic is a substance applied to skin for the purpose of eliminating or reducing the number of bacteria present
antiseptic doesn't kill spores and cannot be used as disinfectants
different organisms have varying ability in withstanding chemical and physical treatment due to different biochemical composition of these organisms and various mechanism that they use to protect themselves
is a bacteria where spores are coated with proteins, lipids, and carbohydrates as well as dipicolinic acid and calcium
Spore forming bacteria
the cell wall is high in lipid which enables them to become resistant to most environmental stress such as desiccation
myobacterium spp.
prions is a naked pieces of proteins, similar to viruses, but without nucleic acid, that is most resistant to the action of heat, radiation and chemicals
prions is an agent that able to cause the generative disease of our nervous system
the amount of organism present in the object yo be treated referred to as microbi load.
Number of organisms
the higher the number of organism, the longer the exposure time needed to eliminate 99.9% of the microorganism
The amount needed to destroy microorganism varies based on the agent to be used
concentration of disinfecting agent
blood, pus, and mucus are examples of organic materials that may prevent full contact of agent to the organic, hence limiting its action
presence of organic material
instrument that we use in lab sometimes are made up of biomaterial which exempts them to disinfection or sterilization due to possible damage
nature of surface to be disinfected
It is critical to observe proper contact time of the agent and the object to be disinfected or sterilized
too little contact time does not allow the agent to work properly
contact time
disinfectants are usually used at room temperature (20 to 22°C.)
too high to low temp may inactive disinfectants and sterilants
Temperature
It is important important consider the pH of the material to be treated and the agent itself.
Manufacturers usually optimize this factor to achieve maximum activity
pH
certain bacteria have the ability to form communities of layers of bacteria with protective shield called
biofilm
biofilm formation may require longer contact time or increase in the concentration of the agent
some disinfectants may inactivate the action of each other hence it is important to consider the
compatibility of disinfectants
autoclave operates based on the principle of steam under pressure.
Sterilization: 121 degrees celsius from 15lbs/ in2 for 15mins
Decontamination: 135 degrees celcius for 30lbs/in2 for 30mins
Biological indicator of autoclave is geobacillus stearothermophilus
purple indicates nonsterility
yellow indicates sterility
Tyndalization is a fractional discontinuous sterilization and discontinuous heating
Effective indication: 100 degree celsius for 30-60minutes
Instrument: Arnold's sterilizer
Inspissation is thickening through evaporation
Effective indication: 75-80 degrees celsius for 2 hours
Instrument: Inspissator
Direct heat: direct application of flame in aseptic technique; until red hot
Dry/Hot air oven: sterilization of heat resistant materials
EI: 160-180° C for 1.5 to 2 hours
Biological Indicator of Dry/Hot Oven: Bacillus atropheus
Incineration: burns materials into ashes; used in the disposable of biological wastes
EI: 870-980° C for 2 seconds
Ionizing Radiation works by alkylation of nucleic acid of bacteria using high energy short wavelength deep penetrating gamma rays
used for heat sensitive materials
biological indicator of ionizing radiation: Bacillus Pumilis
Filtration used membrane filters that are usually made of plastic polymers or cellulose esters that contains pores
Filtration
Water/ liquid solutions/ antibiotics/ vaccines
usually uses a thin membrane filter of cellulose acetate with different pore size depending on the intended purpose
Filtration
Water/ liquid solution/ antibiotics/ vaccines:
0.45-0.80 Mm - most bacteria, yeast, and molds are retained but may allow passage of Pseudomonas like organisms.