Lecture 19-20 Control of Microbial Growth Flashcards
Disinfection
the use of physical or chemical agents to inhibit or destroy microbes
Two types of chemicals used for disinfection
antiseptics and disinfectants
Antiseptics
chemicals applied to living tissue
Disinfectants
chemicals applied to inanimate objects
Examples of antiseptics
hydrogen peroxide and betadine
Example of a disinfectant
lysol
Aseptic techniques
techniques used to prevent microbial contamination of instruments, labs, personnel, and patients in surgery, pharmaceuticals, and food products
Sterilization
destruction or removal of ALL viable microorganisms from an object or habitat
True or False: sterilization removes vegetative cells and endospores
TRUE
Impact of Joseph Lister
used phenol (carbolic acid) as the first antiseptic spray to disinfect surgical rooms
Bacteriostatic
agents that inhibit, but do not kill microbes; often reversible (ex. clindamycin)
Bacteriocidal
agents that kill bacteria (ex. disinfectants & antiseptics)
Bacteriolytic
agents that kill by lysis and release cytoplasmic content (ex. penicillin)
Total cell count
a direct microscopic count (includes both living and dead cells)
Viable cell count
CFU/mL (includes just living cells)
Trend for bacteriostatic control
total cell count and viable cell count equally flatline
Trend for bacteriocidal control
total cell count flatlines while viable cell count decreases (dead cells remain intact)
Trend for bacteriolytic control
total cell count and viable cell count equally decrease
Population death rate is ____.
constant
What is the typically population death rate?
90% of survivors die per unit of time
Decimal reduction time
treatment time for a 1 log decrease in population
What influences decimal reduction time?
population load, environmental factors, and time of exposure
Three types of physical methods for heat control
heat, radiation, and filtration
Dry heat for microbial control involves
flame/incinerate, hot air (oven)
