Control of Microbial Growth Chapter 13

what is sterilization

removal/killing of ALL microbes

what is disinfection

inactivation of microbes

what is sanitization

decreasing microbial load

what are biosafety levels

levels of cleanliness assigned to labs

CDC NIH and WHO established 4 level

what is BSL 4

Microbes are high risk of aerosol transmitted infections; frequently fatal without treatment/vaccines

what is an example of a BSL 4

Ebola and Marburg viruses

What is a BSL3

Can cause serious/potential lethal disease through respiratory transmissionw

what is an example of BSL 3

Mycobacterium tuberculosis

what is BSL 2

Microbes indigenous; diseases of varying severity pose moderate risk to environment and workers

what is an example of BS2

Staphylococcus aeurus

what is BSL 1

Microbes not known to cause disease in healthy hosts and pose minimal risk to environment and workers

what is an example of BSL 1

nonpathogenic strains of E. coli

what are the requirements for controlling BSL 1

Sink for handwashing and a door to close off biolab

what are the requirements to control BSL 2

BSL1 + PPE, self closing doors, eyewash station, autoclave or sterilization method

what are the requirements for BSL 3 labs

BSL 2 + respirator, bio safety cabinets, hands free wash sink, two sets of doors

what are the requirements for BSL 4

BSL 3 + full biohazard suit, shower on exit, lab must have own air supply

Critical level of clean

must be sterile; items contact sterile tissue (blood)

semi critical level of clean

does not require sterilization but does require high disinfection; items might contact non sterile tissue (gut)

non critical

does not require sterilization; items don’t penetrate tissue (stethoscopes on skin)

what are methods of sterilization

heat

pressure

filtration

chemical sterilants

aseptic technique used to prevent ______

sterile environment from becoming contaminated

what are some forms of disinfection

antiseptics - act on microbes but not on organism

most don’t kill endospores examples are hydrogen peroxide and alcohol

example of sanitization and degerming

handwashing, may be combined with disinfectant to reduce microbes

what are cides and what are some examples

cides- kill

bacteriocidal

viricidal

fungicidal

what is static and what are some examples

stop growth;

bacteriostatic

viristatic

fungistatic

degree of control can be observed w/ _____

microbial death curve

what are some physical means of control that are often applied to fomites (clothing etc.)

temperature

radiation

filtration

desiccation

pressure

what is the oldest and most common form of sterilization that alters membranes and denatures proteins

heat

lowest temp that will kill in 10 minutes

thermal death point

length of time to kill at a certain temperature

thermal death time

incineration; direct application of high heat more than 250C (Bunsen burner)

DRY HEAT

Application of high temperature liquid/vapor ex would be autoclave

MOIST HEAT

Do autoclaves kill viruses and endospores

yes because they raise temperature of water above boiling point by raising pressure to 15 psi for 20 minutes

semi sterilizes food but does not ruin food quality is known as

pasteurization

usually not sterilization but static, it slows metabolism but will grow when temps are raised and ultra low temps -80C can be used for perservation

Refrigeration and freezing

Forms of pressure sterilization

pascalization and hyperbaric chambers

high pressure used in food industry to kill microbes

pascalization

can be used to treat infections, induce high levels of oxygen to saturate infection site

hyperbaric chambers

also known as dehydration; creates difference in osmotic pressure through salt or lyophilization to remove water

Desiccation

what kind of radiation enters cells and disrupts molecular structures such as DNA

Ionizing radiation

what are some examples of ionizing radiation

x-rays, gamma rays

can be used to sterilize non autoclave items and an alternate to canned food pasteruization

what kind of radiation does not penetrate glass, plastics, etc. but can damage cells with direct exposure

non ionizing radiation

what are some examples of non ionizing radiation

uv radiation

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

sonification

what uses a barrier to physically separate microbes

filtration

what do phenols do

denature proteins and membranes

what are some examples of phenols

carbolic acid - first used by joseph lister for surgical wounds

lysol

triclosan- commonly found in hand soaps but was banned in 2017

what binds to and inhibits sulfur containing amino acids of proteins

heavy metals

what are some examples of heavy metals

mercury,

silver

copper sulfate

zinc oxide

what heavy metal was used to treat syphilis but banned bc of neural toxicity

mercury

what heavy metal is used today to treat burn wounds, pediatric opthalmia, neonatorum and in antibiotics

silver

what heavy metal is used as algicide to treat pools

copper sulfate

what heavy metal is used in calamine lotion and baby powder

zinc oxide

what are some halogens that are used

iodine

chlorine

flourine

what halogen oxidizes cellular components; commonly used as an iodophor

iodine

what halogen is used to treat water

chlorine specifically hypochlourous acid

bleach is also known as

sodium hypochlorite

flourine is most recognized in ____ products because it provides disruption of microbial fermentation

dental products

what chemical form disrupts membranes and denatures cytoplasmic proteins

alchohols

what chemicals lower surface tension of water and are in most soaps and detergents

surfactants

what are made up of fatty acid salts, not cidal or static but means of mechanical removal

soaps

what are synthetic polar and non polar molecules

detergents

what are cationic detergents; mimic phospholipids and can insert into lipid bilayer. Common form is LYSOL

Quaternary ammonium salts

cationic molecules that disrupt membrane; are not active against naked viruses, are known as

bisbiguanides

bisiguanide that is common surgical scrub and long lasting than iodophors

chlorhexidine

what type of bisbiguanide is faster acting surgical scrub and is up and coming

alexidine

what inactivates enzymes and nucleic acids

alkylating agents

what agent fixes specimens by cross linking proteins

formaldehydew

what acts faster than formaldehyde; and is a common disinfectant of surgical equipment

glutaraldehydew

what is gaseous sterilizer that has high penetrating ability

ethylene oxide

peroxygens are ____

oxidizing agents tha produce radical oxygen to disrupt macromolecules.

what is a common and cheap disinfectant

hydrogen peroxide

what is present in acne medications; very effective against propionbacterium acnes

benzoyl peroxide

agent in toothpaste that combats biofilms

carbamide peroxide

this is used to clean air and water supply

ozone gas

examples of some preservatives are

sorbic acid

benzoic acid

propionic acid

sulfur dioxide

nitrites

methods used to test effectiveness of antiseptics and disinfectants

phenol coefficient - how strong agent relative to phenol

disk diffusion - measures degree of inhibition

use dilution test - used on item to look at effectiveness in real time

in use test - detects if solution is contaminated