Microbiology Exam 4 - Ch 13

Biological safety level requirements: BSL-2 (+4)

BSL-1 plus: PPE self closing doors eyewash station autoclave or sterilization method

Biological safety level requirements: BSL-3 (+4)

BSL-2 plus: respirator bio safety cabinets hands-free wash sink two sets of doors

Biological safety level requirements: BSL-4 (+4)

BSL-3 plus: full biohazard suit shower on exit decontaminate all material on exit lab must have own air supply

heavy metals (in book)

MOA: binds to and inhibits proteins not exclusive to microbes -mercury - treated syphilis but banned because of neural toxicity effects - silver - used today to treat burn wounds, pediatric ophthalmia neonatorum, and in antibiotics -copper sulfate - used as algicide to treat pools -zinc oxide - calamine lotion, baby powder

alcohols (in book)

MOA: disrupts membranes and denatures cytoplasmic proteins used as 70% to allow better cell penetration only viricidal for enveloped viruses can be used in combo with iodine

antiseptic

acts on microbes but not organism/tissue

alkylating agents (in book)

agents replace hydrogen atom with alkyl group MOA: inactivates enzymes and nucleic acids formaldehyde - fixes specimens by cross-linking proteins glutaraldehyde - acts faster than formaldehyde; common disinfectant of surgical equipment ethylene oxide - gaseous sterilizer that has high penetrating ability

phenols (in book)

carbon molecule with benzene ring and -OH group MOA: denature proteins and membranes examples: -carbonic acid - first used by joseph lister for surgical wounds -lysol - original formulations (now is quaternary compound) -triclosan - commonly used in hand soaps; banned by FDA in 2017

quaternary ammonium salts (surfactants) (in book)

cationic detergents similar to phospholipids and can insert into lipid bilayer common day lysol

bisbiguanides (in book)

catonic molecules that disrupt membrane not active against naked viruses, Mycobacteria tuberculosis, etc. chlorhexidine - common surgical scrub and longer lasting than iodophors alexidine - faster acting surgical scrub "up and coming"

surfactants (in book)

chemicals that lower surface tension of water in most soaps and detergents soaps - fatty acid salts (not -cidal or -static but means of mechanical removal) detergents - synthetic polar and non-polar molecules -anionic - neg anion on chain -cationic - pos anion on chain

sterilization

complete kill removal of all microbes from fomite (inanimate object) or organism several methods: -heat -pressure -filtration -chemical (sterilants) aseptic technique is used to prevent sterile environment from being contaminated

sanitization (pt 2)

decrease of microbial load usually mechanical - washing hands, wiping with paper towel, etc. may be used in combination with disinfectant to maximize microbial reduction

sanitization (in book)

decreasing microbial load

level of clean in the clinic: semicritical

do not require high level sterilization items might contact non-sterile tissue (i.e. gut)

level of clean in the clinic: noncritical

do not require sterilization items do not penetrate tissue (i.e. stethoscopes on skin)

2 methods of heat sterilization (in book)

dry heat - aka incineration; direct application of high heat (>250 C) (example: bunsen burner) moist heat - application of high temperature liquid/vapor. beneficial because it penetrates better than dry heat (example: autoclave)

sonication (in book)

high frequency sound waves to disrupt cell structure causes bubbles to form inside cells and induce lysis

pascalization (pressure sterilization)

high pressure used in food industry to kill microbes hyperbaric chambers can be used to treat infections (induces hypoxia to saturate infection site with oxygen) used in combination with temperature in autoclaves

decimal reduction time (DRT)

how much time it takes to kill 90% (1 log reduction) of population

disinfection (in book)

inactivation of microbes

disinfection

inactivation/kill of microbes on fomites some microbes may not be inactivated -disinfection does not equal sterile most do not kill endospore -Ex: hydrogen peroxide, rubbing alcohol

halogens (in book)

iodine - oxidizes cellular components; commonly used as an iodophor (complex with organic molecule) chlorine -hypochlorous acid - Cl + H20; used to treat water -sodium hypochlorite - bleach -chloramine - Cl + NH3; very stable ("swimming pool smell") fluorine -most recognizable with dental products -deposits in tooth enamel and provides disruption in microbial fermentation and processes

two types of radiation (in book)

ionizing radiation: enters cells and disrupts molecular structures such as DNA -X-rays and gamma rays -can be used to sterilize non-autoclave items -can be alternative to pasteurization in canned foods non-ionizing radiation: does not penetrate glass, plastics, etc. but can damage cells with direct exposure - UV radiation - forms thymine dimers in DNA causing lethal mutations

-cides

kill

many factors affect success of control such as:

length of exposure, concentration of agent, population level

thermal death time (in book)

length of time to kill at a certain temperature

Biological safety level (in book)

levels of cleanliness assigned to labs CDC, NIH, and WHO establishes 4 levels (in textbook)

thermal death point (in book)

lowest temperature that will kill in 10 minutes

disinfectant/preservative effectiveness testing

mandated by many agencies (FDA, EU, etc.) -what level of kill can the agent have? -how long does it last? -what microbes does it work on?

microbial death curve (in book)

measure of percentage of kill

degree of control can be observed with ________

microbial death curve

physical means of control

most are applied to non-living (i.e. host) types: 1. temperature 2. radiation 3. filtration 4. desiccation

preservatives (in book)

most inhibit microbial growth in food products in foods, important to be non-toxic examples: - sorbic acid - benzoic acid - propionic acid - sulfur dioxide - nitrites

level of clean in the clinic: critical

must be sterile items contact sterile tissue (i.e. blood)

heat sterilzation

oldest and most common alters membranes and/or denatures proteins

peroxygens (in book)

oxidizing agents that produce radical oxygen to disrupt macromolecules hydrogen peroxide - common and cheap disinfectant benzoyl peroxide - present in acne medications; very effective against propionibacterium acnes carbamide peroxide - agent in toothpaste that combats biofilms ozone gas - used to clean air and water supply

disinfectant/preservative effectiveness testing: methods (in book)

phenol coefficient - how strong is the agent relative to phenol disk diffusion - measured degree of inhibition

supercritical fluids (in book)

pressure and temp are increased in molecules to have properties between liquid and gas (ex: supercritical CO2) allows for easier cell penetration and formation of carbonic acid and increase acidity non-reactive, non-toxic, and non-flammable good for many vulnerable materials such as foods and some tissues

autoclave (in book)

raise temperature of water above boiling point (about 121C) by raising pressure to 15 psi kills viruses and endospores

controlling microbial growth: main goal

reduce microbial load and reduce infection or contamination

sterilization (in book)

removal/killing of ALL microbes

pasteurization (in book)

semi-sterilizes food but does not ruin food quality many methods rely on "flash" heating foods to kill most microbes

Biological safety level requirements: BSL-1

sink for hand-washing and door to close off lab

-static

stop growth

filtration (in book)

use of barrier to physically separate microbes useful when media cannot be autoclaved (ex: urea broth) filters usually have pore size of 0.2 micrometers (or smaller for viruses)

high energy radiation

used to kill or inhibit microbes

refrigeration and freezing (in book)

usually not sterilization method but static slows metabolism but will grow when temperatures are raised (reason why USDA recommends thawing at temps lower than optimal) ultra low temps (-80C) can be used for preservation