Study Guide: Sterilization and Disinfection

Disinfection – Eliminates a ___ scope of microorganisms (___ bacterial endospores) “a little less killing”

defined; some

Sterilization – Destruction of ___ forms of life (including bacterial endospores)

all

Antiseptic – substance applied to the ___ to eliminate a ___ scope (CANNOT be used as a disinfectant!)

• Not all antiseptics are the ___! Antiseptic to prep surgical site is likely to have a higher degree of inhibition than a regular alcohol pad.

• Do ___ kill spores!

• Regulated by ___

skin; defined; same; not; FDA

Disinfectant – substance applied to ___ objects to eliminate a ___ scope

• Regulated by ___ ____ and ___ Agency (EPA)

inanimate; defined; US Environmental; Protection

Contact time – amount of time a disinfectant/sterilizing agent must ___ in contact with an object or surface to achieve the ___ level of microbial killing.

remain; desired

Contact time depends on:

• ___ itself

• ___-value

• ___ (number of organisms present on an object prior to disinfection/sterilization) of the object

• Type of ___

• Presence of ___ material (can react w/ and inactivate some disinfectants)

• Temperature

agent; D; Bioburden; microorganism; organic

D-value – time taken under given conditions to reduce population by ___ log (___%)

• Manufacturer data shows that x amount of contact time will achieve appropriate killing power is ___ on this!

• Usually set for the ___ organism on the list to kill – if it kills that, everything else is dead.

1; 90; based; hardest

Factors that can affect the efficacy of disinfecting/sterilizing agent:

1. ___ of organisms and ___ of organisms

2. ___ of disinfecting agent

3. Presence of ___ material (serum, blood)

4. Nature of ___ to be disinfected

5. ___ time and ___ (dictated by manufacturer)

6. pH

7. ___ (may cause increase in contact time and/or concentration)

8. Compatibility of disinfectants and sterilants

types; number; concentration; organic; surface; contact; temperature; biofilms

Prions (infectious particles - misfolded proteins that cause other proteins to misfold) are the ___ resistant thing to get rid of – cannot be destroyed by ___. Not ___ worried about unless patient tests positive for a prion mediated disease.

most; autoclave; typically

Types of organisms from most resistant to least: (that we worry about sterilizing or disinfecting to a certain degree in ___ practice)

• Bacterial ____ (killed with autoclaves and some chemicals – but w long contact time)

• ____

• ___-lipid viruses

• ___

• ___

• ___ viruses

List is all taken care of via ___ treatment – autoclave is capable of taking care of it all (minus prions).

everyday; endospores; mycobacteria; non; fungi; bacteria; lipid

chemical

Microbial load (Bioburden) – # of organisms ___ before starting disinfecting/sterilizing

• Higher # = ___ exposure times

present; longer

Concentration of disinfecting agent ___, follow manufacturer’s instructions on prep, dilution, and use.

Proper concentration ensures ___ of target organisms and promote safe and cost-effective practices.

varies; inactivation

Presence of Organic Material (Serum, blood) can ___ some disinfecting agents.

• Prevents ___ contact between object and agent

• Always want to try to ___ remove as much contaminant as possible ___ using chemical agents!

inactivate; full; physically; before

Disinfectants generally intended to be used at ___ temperature (20-22C)

• Activity increases w/ ___ temp and vice versa

• Can be inactivated in ___ temps (high or low)

room; increased; extreme

What are the physical methods of disinfection/sterilization?

Heat, Filtration, and Radiation

Heat – most ___ physical method used to eliminate microorganisms!

• moist heat (___)

• dry heat

• pasteurization (___ industry)

common; autoclave; food

Moist heat (autoclave)

• ___ method of choice for heat-___ objects

• Heat under steam ___ (___C for ___ min)

• ___ microorganisms and endospores destroyed (except prions)

Sterilization; stable; pressure; 121; 15; all

Dry heat

• ___

• For___, oils, or something that cannot get ___

• ___ exposure at ___ temps

sterilization; glassware; wet; longer; higher

Pasteurization

• ___, not sterilization (disinfection of ___ infectious agents we care about in ___ products)

• Does ___ kill spores!

• Food industry: High Temp Short Time (HTST): ___ C for ___ sec

Disinfection; main; food; not; 72; 15

Filtration – physical method that is best used when you have something in ___ volumes!

• ___ filtration

• ___ filtration

small; membrane; HEPA

Membrane filtration: filters liquid through very ___ pore size (ex. Pore size <___ um – most bacterial cells are about 1 um in width, blocks them!)

• uses ___ or pressure to pull liquid through

• ___ of heat ___ solutions (ex. Antibiotic that must be injected into a patient that is heat sensitive)

small; 0.5; vacuum; sterilization; sensitive

HEPA filtration: filters ___ via hoods/biosafety cabinets and rooms of immunocompromised patients

air

Radiation - physical method that includes ___ and ___-ionizing rays.

ionizing; non

Ionizing Rays

• ___ rays/electron beams – ___wavelength/___ energy (Nukes it!)

• ___ of syringes, catheters, and gloves

  • typically used for ___ sterilization needs

gamma; short; high; sterilization; bulk

Non-ionizing Rays

• ___ rays – ___ wavelength/___ energy

• ___ surfaces (ex. UV on biosafety cabinets)

UV; long; low; Disinfects

Mechanisms of action for chemical disinfectants/sterilants:

1. Reaction with components of the ___ membrane

1. ___ of cellular proteins

2. Reaction with the ___ groups of enzymes

3. ___ of RNA and DNA

cytoplasmic; Denaturation; thiol; damage

Chemical disinfectants/sterilants’ reaction with components of the cytoplasmic membrane blows ___ in membrane, organism then loses structural ___ and everything inside rushes out.

holes; integrity

In chemical disinfectants/sterilants mechanisms of action, ___ damage is key!

• protein denaturation

• reaction w/ thiol groups of enzymes - where oxidizers blow them up, if these get oxidized it ___ protein structure apart!

protein; breaks

Alcohols, Aldehyde compounds, Halogens, QUATS, Phenolics, and gases are all ___ disinfectants/sterilants.

chemical

Alcohols include ___ alcohol and ___ alcohol that denatures ___.

Both an ___ and ___, used in health Care hand washing, surgical hand scrub, phlebotomy, and to disinfect laboratory surfaces or gloved hands.

• inactivated by ___ material

• most ___ at 60-90% concentration (this concentration is better for contact time consideration)

• Does ___ kill endospores!

ethyl; isopropyl; proteins

antiseptic; disinfectant; organic; effective; not

Aldehyde compounds include ___ and ___.

Glutaraldehyde; Formaldehyde

Glutaraldehyde is the ___ of choice for ___-autoclavable (heat-sensitive) equipment!

• Used in practice

  • Has a wide spectrum of killings – sporicidal in ~___ hrs!

    • killing depends on ___ time! Can leave on for a few min to kill most agents; however, to get rid of bacterial endospores would take ~10 hrs of contact time being ___

• Inactivation of DNA and RNA

  • Remains ___ in presence of organic matter (can still work even w/ some organic present - still ___ clean up as much as possible physically before use of chemical)

sterilizer; non; 10; contact; soaked; active; should

Formaldehyde gas ___ hood (not typically used unless for this reason)

• Known ___!

disinfects; carcinogen

Halogens include ___ and ___ compounds.

iodine; chlorine

Iodine solutions are not ___ iodine, it is used in combinations to increase ___ of agent.

It is a common ___ which includes ___-alcohol and other iodine solutions.

• Used in Topical antiseptic in health care personnel hand wash, surgical hand scrub, and patient preoperative skin preparation

• ___ - iodine scrub pad found in blood cx bottles for patient skin, better ___ than alcohol pod (contact time >30 sec)

• can be ___ too

• ___ sporicidal!

straight; solubility

antiseptic; Tincture; Betadine; killing; disinfectant; not

Liquid sodium hypochlorite (___) is a commonly used ___.

• Oxidative effects of ___ acid when chloride ions are ___ in water

• Used in 0.5% to 1% surface disinfectants (___ dilution from stock)

• Contact time: at least ___ min when organic material is present

bleach; disinfectant

hypochlorous; dissolved; 1/10; 3

Advantages of bleach include:

• ___

• broad spectrum of activity

Disadvantages include:

• ___ exposure for sporicidal action, inactivation by organic matter (generally ___ sporicidal - kills almost everything else tho)

• corrosive

inexpensive; long; not

Quaternary ammonium compounds (QUATS) is for the ___ of noncritical surfaces (for general housekeeping; bench tops, floors, etc)

• Disrupts cell ___

• ___ sporicidal or tuberculocidal!

• Inactivated by ___ organic matter

disinfection; membrane; not; excess

Phenolics have a ___ spectrum of killing but ___ sporicidal (Chemical compounds are generally not sporicidal)

• Used for ___ of hospital, institutional, and household environments, germicidal soaps.

• Disruption of cell ___ and ___ systems

broad; not; disinfection; walls; enzyme

Gases are usually used for ___ stuff that you cannot heat (___ agent).

Includes ___ oxide and ___ peroxide/Peracetic acid.

industrial; sterilizing; Ethylene; Hydrogen

Ethylene oxide is the most ___ gas for ___

• Used in hospitals and manufacturing industry

• Alkylation of ___ ___ in spores

common; sterilization; nucleic acids

Hydrogen peroxide/Peracetic acid is a ___ in pharmaceutical and medical device manufacturing industry.

sterilant

Skin antiseptics – goal is to eliminate ___ flora

Surgical Scrubs – goal is to eliminate transient flora ___ most ___ flora

The goal is to achieve a certain ___ of disinfection to de-germ the site for a particular amount of ___. This level varies depending on disinfection level ___.

transient; and; resident

level; time; needed

Biofilm – ___ of bacteria on inanimate or animate objects

• Increases contact time and/or concentration

• ___ of organisms that have protective material over them that ___ them from outside environmental factors

• Made out of ___ material composed of polysaccharides, proteins, and nucleic acids

community; layers; shields; snotty

Any solid surface of attachment is at risk of biofilm from organisms that have ___ factors like adhesions or capsules - giving them the capability to form biofilm structures. This causes continual ___ of that material!

• Why it is important to have a very high level of ___ technique!

virulence; contamination; sterile