Chapter 13 Control of Microbial growth Flashcards
What is fomites?
inanimate objects which may have microbes and aid in disease transmission
what are the two factors that will influence the level of cleanliness for a fomite
- the application in which it is to be used
- the level of resistance that the potential bacteria have
What is BSL?
biological safety level
what risk is BSL-1?
Microbes that pose minimal risk
What is needed for BSL-1?
-standard aseptic technique
-handwashing
-doors
what are examples of microbes found in BSL-1?
-nonpathogenic strains of e.coli and bacillus subtilis
-viruses that don’t infect humans
-ex. baculovirus (insects)
What risk is BSL-2?
moderate risk to workers and environment
what precaution is used in BSL-2?
-restricted access
-required PPE
-biological safety cabinet
-self-closing doors
-eye washing
-autoclave
what is a autoclave?
a specialized device for sterilizing materials with pressurized steam before use or disposal
what are the bacteria in BSL-2?
-“indigenous”
-staphylococcus aureus
-salmonella spp.
-hepatitis, mumps, and measles viruses
what risk is BSL-3?
microbes that cause serious or potentially lethal diseases through respiratory transmission
what kind of microbes are in BSL-3?
-indigenous and exotic
- mycobacterium tuberculosis, bacillus anthracis, West Nile virus, HIV
what precaution is needed in BSL-3?
-PPE
-respirator and work in biological safety cabinets
-hands free sink and eyewash station
-directional airflow
what risk is BSL-4?
most dangerous and fatal
what kind of microbes are in BSL-4?
dangerous and exotic, posing a high risk of aerosol-transmitted infections
-ex. ebola virus and marburg virus
what precaution is needed in BSL-4?
-full body protection suit with pressure higher in the suit than outside
-HEPA-filtered exhaust
-not many labs in the US
what is sterilization?
-the most extreme protocol for microbial growth
-the complete removal or killing of all vegetative cells, endospores, and viruses
asepsis
maintain sterility
what is sepsis?
a systemic inflammatory response to an infection that results in high fever, increased heart and respiratory rates, shock, and death
what is commercial sterilization?
uses heat low enough to preserve the food content but high enough to kill microbes
what is a common bacteria in canned food?
c.botulinum which is found in soil
what is the goal of commercial sterilization?
1 endospore per can
what is disinfection?
inactivates most microbes by using chemical or heating methods
how is disinfection not sterilization?
endospores tend to survive even when all vegetative calls have been killed
what are antiseptics?
chemically safe for use in living skin or tissues
- ex. hydrogen peroxide and isopropyl alcohol
what is degerming?
which microbial numbers are significantly reduced by gently scrubbing living tissue
-ex. hand washing or alcohol in wipe
what is sanitation?
cleaning of fomites enough deemed safe for the public
- commercial dishwashing, regular surfaces
what is the D-value?
the amount of time it takes for a specific protocol to produce a one-order of-magnitude decrease in the # of organisms or death of 90% of the population
what does the microbial death curve show?
describes the progress and effectiveness of a particular protocol
what are the factors that affect the effectiveness of the disinfectant?
the concentration and length of time
what is a thermal death point?
the lowest temp. in which all microbes die in 10 minutes
what is the difference between gravity displacement autoclaves and prevacume autoclaves?
Gravity displacemnt autoclaves- air sits at the bottom and it filters out
prevacume: air is removed before the steam enters.
what is pasteurization?
kills pathogens and reduces the amount of spoilage while maintaining food quality
what does refrigeration do?
prevent microbial growth
what is hyperbaric oxygen therapy do?
- increase oxygen
- increases WBC
- saturation in tissue helps with infections but there is a risk of oxygen toxicity.
what does desiccation do?
- it is drying
- controls microbial growth does not kill all microbes or its endospores
lyophilization?
freeze drying
- snap frozen then placed under vacuum
-very effective in preventing microbial growth and preserving the integrity of food
what does ionizing radiation include?
x-rays, gamma rays, high energy electron beams
what does ionizing radiation do?
it passes into the cell alters the molecular structures and damages the cell
ex. one way is putting breaks in the DNA
what does nonionizing radiation include?
UV light
how does UV light disinfect?
it causes thymine dimers to form between adjacent thymine, causing the DNA to not incorporate the right complementary (AA), creating a mutation and then death
What are HEPA filters?
high-efficiency particulate air filter
pore size 0.3um
what are membrane filters?
filters for liquid functions
pore size 0.2um
what are BSC?
-Biological safety cabinets
-filters the air coming in, filters the air coming out and or both
