Podcast
Questions and Answers
What is the maximum time required for sterilization by dry heat at $150^ ext{°}C$?
What is the maximum time required for sterilization by dry heat at $150^ ext{°}C$?
- 2 hours
- 3 hours (correct)
- 1 hour
- 4 hours
Which microorganisms are considered harmless and classified as Class I?
Which microorganisms are considered harmless and classified as Class I?
- Serratia marcescens
- Ebola
- Staphylococcus aureus
- Lactobacillus (correct)
At what temperature range do most vegetative bacteria get killed during steam sterilization?
At what temperature range do most vegetative bacteria get killed during steam sterilization?
- $80-90^ ext{°}C$
- $60-70^ ext{°}C$ (correct)
- $100-110^ ext{°}C$
- $50-60^ ext{°}C$
What is the minimum temperature and time for autoclaving to be effective?
What is the minimum temperature and time for autoclaving to be effective?
What is the purpose of using cotton wool and aluminum foil in the sterilization process?
What is the purpose of using cotton wool and aluminum foil in the sterilization process?
What does Tyndallization involve in its sterilization process?
What does Tyndallization involve in its sterilization process?
What type of microorganisms is classified as opportunistic pathogens?
What type of microorganisms is classified as opportunistic pathogens?
When autoclaving, what is the purpose of removing air from the chamber?
When autoclaving, what is the purpose of removing air from the chamber?
Flashcards
Risk groups of microorganisms
Risk groups of microorganisms
Refers to a system for classifying microorganisms based on their potential danger. It has four levels, ranging from harmless to extremely dangerous.
Opportunistic pathogens
Opportunistic pathogens
Microorganisms that can cause infections in individuals with weakened immune systems. Their potential for causing disease is considered opportunistic.
Sterilization by dry heat
Sterilization by dry heat
A method of sterilization involving wrapping materials in aluminum foil and cotton wool, then exposing them to high temperatures.
Autoclaving
Autoclaving
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Tyndallization
Tyndallization
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60-70°C temperature
60-70°C temperature
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80-90°C temperature
80-90°C temperature
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Above 120°C temperature
Above 120°C temperature
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Study Notes
Microbiology Lab Safety
- Basic rules apply to chemical labs, including GHS hazard pictograms and H/P statements
- Additional safety precautions needed for infectious agents, such as Ebola and Sars-CoV-2, are important
- Some microorganisms considered harmless, such as Lactobacillus and Bacillus subtilis
- Other microbes are potentially harmful, including opportunistic pathogens like Serratia marcescens, certain coliform bacteria, or Staphylococcus aureus.
- Some microorganisms can affect animals or plants
Sterilization Methods
- Sterilization methods depend on the material and time required
- Dry heat sterilization is used for glass and metal, typically at 180°C for 30 minutes or 150°C for 3 hours (for items wrapped in cotton wool).
- Steam sterilization kills most vegetative bacteria at 60-70°C, but spores can resist up to 120°C depending on exposure time
- Tyndallization involves heating material 3 times to 100°C for at least 8 hours
- Autoclaving uses saturated steam and pressure (at least 1 atmosphere) to sterilize material at 121°C for 20 minutes.
- Faster autoclaving methods exist at higher temperature, like 134°C for 6 minutes for medical applications, but this method requires the container to be filled at most 3/4 of the way.
- Materials and labels need to be waterproof
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