Module 5 Flashcards
What is sterilization?
destruction/removal of all viable organisms, spores and acellular entitues (viruses)
What is disinfection?
kills, inhibits or removes microorganisms that may cause disease (not spores)
What is the difference between disinfection and sterilization?
Disinfection: kills, inhibits or removes microorganisms, typically targeting most vegetative cells, BUT NOT SPORES
Sterilization: eliminates all viable organisms and spores
What are disinfectants?
agents (often chemicals) used for the treatment of inanimate objects to kill or inhibit pathogenic microorganisms
What is antisepsis
agents that prevent infection by destruction or inhibition of microorganisms on living tissues
Whats more toxic: antisepsis or disinfection and why
disinfectants because antisepsis has chemical agents that can be applied to tissues without causing damage
What is sanitization?
reduces microbial populations to safe levels based on public health standards
what is chemotherapy?
use of chemical agents to kill/inhibit microorganism growth in host tissues
What are cidal agents?
kills pathogens and many non-pathogens but not necessarily spores
What are examples (3) of cidal agents?
- bactericides
- fungicides
- viricides
What are static agents
prevent growth of microorganisms when present
What are examples (2) of static agents?
- bacteriostatic agents
- fungistatic agents
What is a bacterial endospore?
a dormant stage formed by some bacteria that provides protection against various harsh conditions
What 6 conditions influence the effectiveness of antimicrobial agents?
- temp
- local environment
- contact time
- concentration/intensity
- population size
- population composition
Why are bacterial endospores considered a challenge in microbiology?
because they are highly resistant and can survive extreme conditions, making them difficult to eliminate
How does microbial population death occur after exposure to a lethal agent?
occurs exponentially, meaning it doesn’t happen instantly but rather decreases rapidly over time
What happens to the killing rate of a microbial population as it decreases?
the killing rate may slow if there is a more resistant strain present
Why is it important to measure the killing efficiency of a microbial agent?
important to understand its effectiveness and ensure it can properly reduce or eliminate populations, especially resistant strains
What is Decimal Reduction Time (D-value)?
time required to kill 90% of microbes or spores under specified conditions
What is the Z-value?
measure of the temperature sensitivity of an organism
- indicating the temp change that will cause the D-Value to change by a factor of 10
Why is it important to confirm the death of a viable but non-culturable (VBNC) cell?
because if they recover, they may regain the ability to reproduce and potentially cause infection or contamination
What are 3 types of control
- mechanical/physical control methods
- chemical
- antimicrobial chemo (drugs)
What is antimicrobial chemotherapy?
use of drugs to kill or inhibit the growth of microorganisms
Why is boiling water not sufficient for sterilization?
will not destroy bacterial spores, so it disinfects not sterilizes
What are examples of mechanical/physical control methods
heat, filtration, radiation
what are examples of chemical control methods
disinfectants, antiseptics
what does moist heat sterilization do?
- degrades nucleic acids 2. denatures pr
- disrupts membranes
What conditions are necessary for moist heat sterilization?
- must be done at temp greater than 100C
- using saturated steam under pressure in an autoclave
- both temperature and time is important
is moist heat sterilization effective against spores?
YES
What is a critical aspect of quality control in sterilization?
ensures that the sterilization process is effective, confirming that all microorganisms, including spores, are killed
What is the primary purpose of pasteurization?
used to kill pathogens and slow spoilage by reducing the total load of organisms WITHOUT sterilizing the product
What are the conditions for flash pasteurization (HTST)?
- heating liquid to 72C for 15 seconds, followed by rapid cooling
- extends milk shelf life to 2-3 weeks
What is ultrahigh-temperature (UHT) pasteurization?
- heating at 140-150C for 1-3 seconds
- extends milk shelf life to 6-9 months
What are 3 effects of low temp
- freezing stops cell reproduction bc of lack of liquid water
- some cells killed by ice crystal disruption of cell membranes
- refrigeration slows cell growth
What effect does freezing have on microbial cells?
stops cell reproduction due to the lack of liquid water
- some cells may be killed by ice crystal disruption of cell membranes
How does refrigeration affect microbial growth?
slows down microbial growth by reducing metabolic activity, thereby prolonging the freshness of food
What are the conditions for dry heat sterilization?
- requires higher temp (160-170C)
- longer exposure time (2-3 hours)
TRUE OR FALSE: dry heat sterilization is used in the presence of water
FALSE