Lecture 6 Flashcards by Becky Mckay

What is sterilization?

The absolute removal or destruction of all microbial life and viruses

Spores and endospores

How well did you know this?

Not at all

Perfectly

What is disinfection?

Destruction of pathogenic microorganisms

Kills most

Ex. Bleach, alcohol

How well did you know this?

Not at all

Perfectly

What is antisepsis?

Disinfection of living tissue

Requires less harsh chemicals

How well did you know this?

Not at all

Perfectly

What is degerming?

Removal of most microbials from a limited area

Ex. Alcohol wipes move microbes over (washing hands)

How well did you know this?

Not at all

Perfectly

What is sanitization?

Lowering the microbial counts on a surface such that they are at a safe level

Ex. Washing hands

How well did you know this?

Not at all

Perfectly

Bacteriocidal vs bacteriostatic

Kills bacteria

Stops the growth of microbes (holds at a constant number)

How well did you know this?

Not at all

Perfectly

What is aseptic?

Area free of significant contamination

Ex. Surgery room

How well did you know this?

Not at all

Perfectly

What are the 9 physical methods of microbial control?

Heat

Filtration

Air filtration

Low temp

High pressure

Desiccation

Osmotic pressure

Radiation

Microwaves

How well did you know this?

Not at all

Perfectly

How is heat used as a microbial control?

Kills by destroying their fundamental proteins

How well did you know this?

Not at all

Perfectly

What are the types of ways heat can be used as a physical microbial control?

Moist heat - boiling, autoclave

Pasteurization

Dry heat sterilization - direct flaming, incineration, hot air sterilization

How well did you know this?

Not at all

Perfectly

What are the characteristics of microbial control by boiling?

Beaks hydrogen bonds and denatures protein structures

5 min kills most pathogens and viruses, NO endospores

Disinfects

How well did you know this?

Not at all

Perfectly

What are the characteristics of microbial control by autoclave?

Uses 15 psi pressure and 121 deg of steam

15 min to kill all microorganisms and endospores

Best sterilization (hospitals) by exposing all surfaces to steam temp

How well did you know this?

Not at all

Perfectly

What are the characteristics of microbial control pasteurization?

Is not a sterilization method

Eliminates pathogens

Reduces microbial counts to slow food spoilage

Mild heating of a liquid (milk,beer)

63 deg for 30 min

Types: HTST pasture, UHT pasture

How well did you know this?

Not at all

Perfectly

What are the 2 types of pasteurization?

HTST - high temp shot time. 72 deg for 15 sec. Most common

UHT - ultra high temp. 140 deg for 3 sec. Can be stored without refrigerization ( Phils milk)

How well did you know this?

Not at all

Perfectly

What are the characteristics of dry heat sterilization?

High heat high time

Kills with oxidation

Direct flame - open flam to sterilize tools at red hot

Incineration - sterilize and dispose of contaminated material

Hot air - drying oven, 170 deg for 2hrs. Not for temp sensitive material

How well did you know this?

Not at all

Perfectly

What are the characteristics is microbial control by filtration?

Vacuum forces
Iquitos through filter with small pores

Bacteria is left behind

Sterilizes temp sensitive liquids like antibiotics, enzymes,culture media

Virus r smaller therefore can pass thru filter

What are the characteristics of air filtration in microbial control?

High efficiency particle air filters used in operating rooms to prevent airborne bacteria from entering

What are the characteristics of low temperature microbial control?

Refrigeration slows or stops microbial growth

Freezing can stop and kill some microbes with reduced metabolic rate (less reproduct and toxin)

What are the characteristics of high pressure microbial control?

Liquid suspension in high pressure to disrupt protein and molecular structure

Kills most bacterial cells (code)

No kill endospores bc not sterilization

What are the characteristics of dessication microbial control?

Bacteriostatic (sleep) ex weather

Removal of water (stops growth but does not kill since microbes can stay alive in a dehydrated state)

What are the characteristics of osmotic pressure in microbial control?

High concentration of salts and sugars makes hypertonic environment causing shrivel

Some bacteria die is both bacteria lysis and static

Mold n yeast is most resistant

What are the characteristics of radiation microbial control?

Destroys DNA using X-ray and gamma rays to penetrate material

Up and high energy electron beams used on surfaces

What are the characteristics of microwave microbial control?

Destroys DNA using X-ray and gamma rays to penetrate material

Up and high energy electron beams used on surfaces longer wavelengths

Cannot kill directly but the high temp it makes can kill

How are disinfectants evaluated for effectiveness?

Disk diffusion method - filter paper soaked in chemical disinfectant diffuses into agar plate -> bacteria is added and grows. Depending on zone of clearance is how effective the disinfectant is to that bacteria

High ethically = the greater effect

What is an example of phenolics?

Lysol

What are the characteristics of phenolics and bisphenols as disinfectants and antiseptics?

Disrupt plasma membrane and denatures protein - bacteriocidal Effective and remains a long time while staying stable with organic compounds - mixable and stays constant Disinfects from saliva and feces contamination Decreases toxicity of other compounds

What is an example of phenolics?

Lysol

What is an example of bisphenols?

Hexachlorophene - skin infection causing bacteria found in nurseries (causes neuro disorders tho) Triclosan - personal hygiene soaps by limiting microbe growth in moist warm areas

What are characteristics of biguanides?

Chlorhexidine - attacks plasma membrane (lots of cells have this so it is very non specific) Controls microbes on skin and mucous membranes as a bacteriocidal Surgery soap 6hrs of active Kills envelope viruses while naked virus are unaffected No effect on endospores

What are characteristics of halogens?

Impaire synthesis and membranes found I. Bleach Chlorine - oxidizes, destroys enzymes Iodine - amber colour. Oldest n effective antibiotic Tincture - aqueous alcohol Iodophors - iodine and organic molecule

What are the characteristics of alcohol as a disinfectant?

Denatures protein and lipid membranes Kills bacteria and fungi Does not kill endospores and naked viruses Not satisfactory antiseptics on wounds Ethanol/ isopropanol - most commonly used

What are the characteristics of heavy metals as disinfectants?

Copper - destroy green algae in fish tanks and pools silver - nitrate 1% in eye drops. Topical cream for burns. Added to dressings and catheters to avoid infection Zinc - in mouth wash mercury inhibit microbes

What are the characteristics of soaps as disinfectants?

NOT an antiseptic Important in mechanical removal of microbes Breaks up oil and washes debris Determine agent All soaps are amphipathic by micelle surrounding oil

What are the characteristics of quaternary ammonium (quarts) as a disinfectant?

Cationic detergents by kill most bacteria and fungi Does Does NOT kill endospores or mycobacteria Less effective for gram neg over pos Affect plasma membrane Antimicrobial, colourless, tasteless, odorless, mom toxic Pseudomonas actively grow in them

What are the characteristics of gaseous chemosterilizers as disinfectants?

Denatures protein Bacteriocidal of endospores and viruses within 4 to 18hr exposure Penetration professional Sterilizes hospital equipment

What are the characteristics of oxidizing agents as a disinfectant?

Oxidize and denatures proteins Good against anaerobic organisms Hydrogen peroxide -wounds Ozone - synthesize with chlorine to disinfect water Benzol peroxide- kills anaerobic bacteria in living tissues (acne)

What are the levels of efficacy of antiseptics?

Least to most Soap and water Aqueous zephiran Tincture of zephiran 1% iodine in ethanol

What is the gradient of resistance in bacteria?

Most to least resistant Prions Endospores of bacteria Mycobacteria Protozoa cysts / vegetative Gram neg Fungi Naked viruses Gram positive Virus with lipid envelope