Control of Microbial Growth Flashcards
What is disinfection?
Destroying all harmful microorganisms
Destroys vegetative cells
NOT the same thing as sterility
When you disinfect something, do you kill the endospores as well?
NO
Disinfectant definition
A chemical used to treat an INERT surface
What is degermination?
Mechanically removing microbes, not really killing them
Ex: Degerming a table top
Sanitization is?
When you lower the microbe count just low enough to where it is safe to consume
Ex: high temp washing or chemical disenfectant
Biocide…?
Kills microorganisms except endospores
Bacteriostasis…?
Inhibits growth
Does NOT kill the microbes
Sepsis is ?
Bacterial contamination
Aseptic means?
Object/ area is free of pathogens
Asepsis means?
Absensce of significant contamination
The rate of microbial death is?
A constant rate
Microbial death is graphed as a?
Log
What are factors that influence antimicrobial effectiveness?
Number of microbes
Time of exposure
Environmental influences
Microbial characteristics
What are the ways antimicrobial stuff damages microbes?
They can damage the lipids/ plasma mebrane
They can damage proteins
They can damage nucleic acids
How can antimicrobials damage lipids?
Damage to the lipids causes leakage of the cell and its components
This stops binary fission
How do antimicrobials damage proteins?
They shut down the enzymes
By damaging proteins, they break hydrogen bonds
Stop binary fission
HOW do antimicrobials damage nucleic acids?
By heat
Radiation
Chemicals
Stops protein synthesis, binary fission
What is the thermal death point? (TDP)
Lowest temp that cells in a liquid culture will DIE in 10 MINUTES
Unit is celsius
What is thermal death time? (TDT)
Minimal time that all bacteria in a liquid culture are dead at a particular temperature
Unit is seconds or minutes
What is the decimal reduction time? (DRT)
The minutes it takes to kill 90 percent of a specific population of bacteria at a given temperature
What are the types of Moist Heat sterilization?
Boiling/ free flowing steam
Autoclaving
Pasteurization
What happens in Boiling/ free flowing steam (moist heat sterilizaton)?
Kills vegetative forms of bacterial pathogens, viruses, and fungi within 10 minutes
Endospores can last up to 20 hours in this process
What do all types of moist heat sterilization do?
Coagulate and denature proteins
What happens in autoclaving?
Uses high temp and pressure to kill microorganisms as well as endospores
Preferred method of sterilization in hospitals
What happens in Pasteurization?
It uses high heat for a short amount of time
Reduces spoilage organisms and pathogens
72 degrees celsius for 15 seconds
What happens when you dry heat?
It kills bacteria by using oxidative effects
What’s an example of dry heating?
Direct flaming
Ex: Innoculating the tools
Types of radiation techniques?
Ionizing
Non- ionizing
Microwaves
Types of ionizing radiation examples?
X-rays
Gamma rays
Electron beams
When using ionizing radiation, how does it work?
It destroys DNA by lethal mutations
Types of non-ionizing radiation?
Ultraviolet
When using non-ioning radiation, how does it work?
Creates thymine dimers which damage DNA
What are the types of physical control of microbial growth?
Heat
Radiation
