Microbiology Test 3 Preparation

angeline martin
Flashcards by angeline martin, updated more than 1 year ago
angeline martin
Created by angeline martin about 6 years ago


Microbial Growth and Control

Resource summary

Question Answer
Sepsis Microbial Contamination
Asepsis absence of significant contamination
Aseptic free from contamination caused by harmful bacteria, viruses, or other microorganisms.
Sterilization Removal of all microbial life
Disinfection Removing pathogens from surfaces
Antisepsis Removing pathogens from living tissue
Sanitization Lowering microbial counts to an acceptable level (based on public health standards)
Biocide / germacide Kills Microbes / kills something alive
Bacteriostasis inhibiting, not killing bacteria
Most resistant 1. Prions- Can't kill (death sentence) 2. Mycobactreia- Mycolic acid can survive on surfaces for 6 months (TB patients) 3.Cysts of Protoza (protists)- encapsulated- in tissues hybrenated in life cycle
Least resistant 1. Viruses with lipid envelope- easiest 2. Gram positive- fairly easy even though there is a thick cell wall
What Determines the rate of death or destruction? A. Characteristics (Ex. Mycobacterium B.Environment Conditions-(blood present) C. Concentration of agent (ex 70% alcohol) D.Time of exposure E. Number of microbes to begin with
How disinfectants/ antiseptics work on Microbes 1. Soap= physical removal 2. Alcohols- disrupt of plasma membrane 3. Phenols- denature (unfold)proteins 4. UV Light- Damage to DNA 5. Hydrogen Peroxide- damage to molecules ex. H2O2 (hydrogen Peroxide)
Control Method (dry Heat) Dry Heat- Oven 350F = 160C- Takes several hours to kill microbes- not as effective a moist heat
Control method 2 Moist Heat / Autoclave Moist heat - Autoclave- Steam pressure cooker 121C for 15 minutes at 15 PSI (lbs per square inch)- Water boils at 100C it doesn't get any hotter than that regardless of how long you boil. You have to add pressure to increase it to 121C.
Control Method 3 Pasteurization 1.Pasteurization- Need heat to kill- ex. Wine- 63C. for 30 minutes 2.Higher Heat Pasteurization- 72C for 15 seconds 3. Ultra High Temperature Pasteurization (UHT)- 140C for 1 second
Control method 4 Incineration Flaming incineration- flaming in lab and medical facilities to get rid of waste such as blood, needles, etc.
Control Method 5 Cold Slows but does not kill 40C refrigerator- slows growth- doesn't kill Minus 20C freezer- ice crystals may kill them- except psychrophiles (cold loving)15C and can grow at 0 degrees (example. Listeria Monocytogenes). Food in freezer only lasts 6 months
Control Method 6 Removal of Water dessication (complete removal of water) prevents growth- dry out or remove water- If you add salt or sugar that draws out water important of in preserving food. Example is how blood is saved from criminals on dried card stock.
Control Method 7 Filtration HEPA Filter (high efficiency particulate air)- filters air membrane filters- filters liquids Used to sterilize things that can't be heated, etc. media, vitamins, etc.
Control Method 8 Radiation UV Light X- Ray Ionizing Radiation= x-rays, gamma rays treating plastic ware to treatment of food. irradiation- radiation damages DNA- UV Light it does not penetrate into things so it should be used on surfaces- UV damages retina of eye - UV causes thymine dimer
Control Method 9 Soaps Detergent a
Chemical Control Phenol Phenol - chemical that isolation of DNA but it denatures DNA- Cresol treats tel pole and railroad ties Phisohex- face wash Lysol- very effective against mycobacterium TB
Chemical Control Chlorehexidine- 1. Used in hand scrubs 2. Low toxicity 3. Very effective against spores, TB, cysts of parasites
Chemical Control Method Halogens column 17 on period table Iodine (for skin), chlorine, betadine, alcohol, bleach (with alcohol)- Note alcohol and iodine make an anticeptic There is only way iodine can be disinfectant is to put in water camping
Alcohols- rubbing alcohol Good disinfectant 60-70 % is best. Need water to assist in the work
Heavy Metals murcury , lead, silver, etc. thimerosal was in vaccines controversy about it being responsible for autism lead paint to keep mold and fungi down Silver nitrate was used to treat nb babies into eyes for gonoreha bacteria, it could go blind- still used today
Copper sulfate swimming pools, fish ponds and aquariums to control microbial growth
Metals are naturally anti microbial
Autism scare article related to 12 children being autistic- it was focused with colitus and connection with vaccines- article published in 1998 10 authors retracted
amonia compounds in most cleaning supplies NH3 (essential elements Nitrogen bacteria) problem with amonia compound - psuedamonas compound can grow in amonia
Preservative sulfites - preserving food- stoppong deday by killing microbes. Nitrates in meats can decay if no preserved.
Aldahyde Formaldehyde- embalming Glutaraldehyde- used in Health care setting- used when biopsy is done and sent to pathology to preserve tissue while tissue is being examined. fixes cells so bacteria don't break down
Gases Ethelyn oxide high toxicity- not wet- has to be completely vented before chamber is open or it could kill
Peroxides Hydrogen peroxide most effective against anarobes because they do not have catalase, oxidase
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