MMI133 Lecture Notes - Lecture 8: Bacillus Stearothermophilus, Disinfectant, Hepa
18 Jun 2018
School
Department
Course
Professor
Sterilization and Disinfection
Antiseptic
Disinfectant used on the skin
Aseptic Technique
Uses methods to exclude microorganisms
Bactericidal
Kills bacteria
Bacteriostatic
Inhibits growth of bacteria (does not kill bacteria)
Disinfectant
Chemical used to destroy many microorganisms
and bacteria
Fungicide
Kills fungi
Pasteurization
Brief heat treatment used to reduce the number of organisms and kill
pathogens (does not kill all bacteria)
Sanitization
Reduction of the number of organisms to a public health standards level
Sterilization
Destruction of all forms of microorganisms
, including spores (Aldehyde
solutions)
Vericide
Inactivates viruses
Ventilation
● HEPA used to make clean air
● Building standards exist for correct air flow
● Isolation room with correct “air locks”
Positive Pressure - air from corridor that cannot get into the room, but air from the room can
go into the corridor (e.g. immunocompromised individuals)
Negative Pressure - air that cannot get from room into the corridor, but air can come in from
the corridor (e.g. contagious individuals)
Physical Means of Controlling Bacteria Growth
1. Heat - hot air can be used, but 1-2 hours is too lengthy for hospital setting.
2. Autoclave - mix of hot air and moisture that only takes 15 minutes to inactivate spores (121
degrees celsius with 15 psi. Spore test is completed in order to determine if autoclaving was
effective.
3. Irritation/Radiation (Gamma or UV rays)
4. Filtration
5. Cold
6. High Pressure
7. Desiccation (drying)
8. Osmotic Pressure
Most important consideration that determines sterilization is whether or not the object is to be
sterilized free of organic matter
(blood, tissue feces etc.)
Spore Test
● Uses bacillus stearothermophilus
● Ampule containing nutrient media and spores of nonpathogenic bacteria are autoclaved with
object, incubation then tests growth
● Growth indicates lack of sterilization (pH will be seen as a colour change or production of
acid or alkali compounds)
● Inactivated spores are unable to produce growth, indicating effective autoclaving
Document Summary
Inhibits growth of bacteria (does not kill bacteria) Chemical used to destroy many microorganisms and bacteria. Brief heat treatment used to reduce the number of organisms and kill pathogens (does not kill all bacteria) Reduction of the number of organisms to a public health standards level. Building standards exist for correct air flow. Positive pressure - air from corridor that cannot get into the room, but air from the room can go into the corridor (e. g. immunocompromised individuals) Negative pressure - air that cannot get from room into the corridor, but air can come in from the corridor (e. g. contagious individuals) Spore test is completed in order to determine if autoclaving was effective. 3: filtration, cold, high pressure, desiccation (drying, osmotic pressure. Most important consideration that determines sterilization is whether or not the object is to be sterilized free of organic matter. Ampule containing nutrient media and spores of nonpathogenic bacteria are autoclaved with object, incubation then tests growth.
