13.1
What are the micro labs at UTA considered?
BSL-2
What is considered the most common and oldest method of microbial control?
heat sterilization
True or false.
Heavy metals are not selectively toxic to microbial cells.
(DOUBLE POINTS)
TRUE
they may bioaccumulate in human or animal cells, as well, and excessive concentrations can have toxic effects on the human body
Where is the in-use test typically used?
in clinical settings
What is one of the most common effects at a hospital?
secondary infections
What are the aseptic measures in a BSL-4 lab?
BSL-3 plus...
full biohazard suit
change clothing on entry
shower on exit
decontaminate all material on exit
lab must have own air supply
raise temperature of water above boiling point (~121C) by raising pressure to 15 psi
autoclave
(moist sterilization)
Why is 70% alcohol more effective in killing microbes than solutions that contain higher concentrations of alcohol?
it allows for better cell penetration
What is the high level of effectiveness?
kill vegetative cells, fungi, viruses, and endospores
What is aseptic technique used for?
to prevent sterile environment from becoming contaminated
What are some examples of things that are considered noncritical clean?
stethoscopes
bed linens
blood pressure cuffs
What is ionizing radiation considered an occasional alternative to?
(DOUBLE POINTS)
pasteurization in canned goods
What are the two types of detergent?
(DOUBLE POINTS if you can explain the differences)
Anionic: negatively charged anion at one end attached to a long hydrophobic chain
Cationic: positively charged anion at one end attached to a long hydrophobic chain
Where are the filter paper disk (in a disk diffusion) placed?
inoculated agar plate
What is B-propionolactone?
plastic bags such as catheters, disposable items in labs and clinical settings, and other pieces of equipment
What kind of procedures are biological safety cabinets good for?
procedures that may disperse agent through the air (called aerosolization)
What is high pressure processing used to kill bacteria, yeasts, molds, parasites, and viruses in food while maintaining food quality and extending shelf life called?
pascalization
What is propionic acid added to?
other cheeses and baked goods; to raw dough to prevent contamination by B. mesentericus
in use-dilution test, what are the steps?
1. stainless steel cylinder dipped in target culture then dried
2. cylinder then dipped into various concentrations of disinfectants
3. cylinder then transferred to fresh media
Define decimal reduction time (DRT) or D-value.
The amount of time it takes for a specific protocol to produce a one-order-of-magnitude decrease in the number of organisms, or the death of 90% of the population
What are the 2 major factors that heavily influence the level of cleanliness?
1. the application for which the item is being used
2. the level of resistance to antimicrobial treatment of the potential pathogen
HTST vs. UHT pasterization
HTST: milk heated at 72C for 15 seconds, then bottled and refrigerated
UHT: milk heated at 138C for 2 or more seconds, then sealed in airtight containers for up to 90 days without refrigeration
nitrites MOA
(DOUBLE POINTS if you can explain how nitrosamines factor into this)
nitric oxide reacts with iron-sulfur groups (disrupts ETC)
What are the steps of an in-use test?
(DOUBLE POINTS)
1. 1 mL sample of the used disinfectant is diluted into 9mL of sterile broth medium that also contains a compound to inactivate the disinfectant
2. about 0.2mL of this mixture is them inoculated
3. look for microbial growth
4. if there are more than 5 colonies, the disinfectant is considered contaminated
What are the 8 pathogens that pasteurization kills?
(DOUBLE POINTS)
1. camplyobacter jejuni
2. coxiella burnetii
3. listeria momcytogenes
4. E. coli O157:H7
5. mycobacterium tuberculosis
6. M. paratuberculosis
7. Salmonella spp.
8. Yersinia enterocolitia