Chapter 7 - Control of Microbial Growth Flashcards
What kills all microorganisms?
Sterilization
What is disinfection?
Destruction of pathogenic organisms on an inert surface
What is a danger of disinfection?
It can damage living tissue
What is Antisepsis?
The destruction of pathogenic organisms on living tissue
What is sanitizer?
A product that lowers the number of microbials to safe levels as set by public health
What does it mean if something is septic?
It is contaminated with pathogenic microorganisms
What is aseptic?
Free of pathogenic microorganisms
What is degermination?
The mechanical removal of microorganisms
What form of microbial growth control is hand soap?
Degermination
What does the -cide ending mean?
Kill
What does the -stat ending mean?
Slow, inhibit
What does the -lytic ending mean?
Rupture of cell (kills most of the time
What 4 factors affect antimicrobial effectiveness?
- Concentration of microbes - less cells, more effective
- Environmental factors - temp., pH, pure or mixed culture
- Time of exposure
- Specific microbial characteristics - resistance to death
What is Decimal Reduction Time?
The time in which 90% of microbial population will be killed at a given temperature
If the temperature is low, what will happen to the Decimal Reduction Time (D)?
It will increase
What is an example of moist heat that discourages microbial growth?
Autoclave - uses water, heat, pressure
What is an example of dry heat antimicrobial?
Oven - used in clinical setting for glassware and metal
What is the lowest temperature at which all microorganisms are destroyed in 10 minutes called?
Thermal Death Point
What is the Thermal Death Time?
The minimum amount of time at which all microorganisms are destroyed at a a given temperature
What is the x-ray an example of?
Ionizing radiation
What is ionizing radiation?
x-ray, gamma ray, electron beams; form hydroxyl free radicals
What is non-ionizing radiation?q
UV, damages cell components, ex. sunburn, damage nucleic acids
What is pasteurization?
not sterilizing, heat decreases number of microorganisms to a safe level using low heat
What is the use of membrane filters to retain certain organisms then treat and destroy or lower cell numbers called?
Filtration
How do toxic chemicals work to combat microbial growth?
gasses - toxic and impede growth
antimicrobials - don’t necessarily kill organisms, concern for environment because they are harmful to living things
What is dessication?
Dehydration of microbes
What form of temperature lowering is most harmful to microorganisms and why?
Slow-low drop, because it causes crystals to form in the cell
What is one way to dehydrate a microorganism?
Placing them in a hypertonic solution (osmotic pressure)
What is the name of any chemical substance used to prevent or treat a wide range of problems?
Chemotherapeutic agent
What form of medicine is made by a living organism?
Antibiotic
What is the name of the lowest concentration of chemotherapeutic agent or antimicrobial that will kill a microorganism?
Minimum Inhibitory Concentration (MIC)
What are 2 ways to evaluate antimicrobials?
- Use dilution test
2. Disk diffusion method
How does the Use Dilution Test work?
Metal rings are dipped in cultures, then soaked in antimicrobial for 10 minutes, rings are then placed on growth media and incubated; look for growth
How does the Disk Diffusion Method work?
Filter paper disks are soaked in anti-microbial and placed on petri dish of microorganisms, incubated, if it works there is a clear zone on the plate
