Week 2 Lecture - Sterilization and Disinfection

What concentration of CHG is used for wound management?

0.05% solution

What concentration of povidone iodine is used for wound management?

0.1-1%

What concentration of povidone iodine is used for surgical preparation?

10% scrub/solution

What concentration of CHG is used for surgical preparation?

4% scrub/solution

Describe the activity of CHG.

bacteriocidal relatively quick; more affective against gram (+) bacteria than it is against gram (-) bacteria; minimal activity against viruses and fungi; not affective against spores at all

Describe the activity of PVI.

bacteriocidal, fungicidal, effective against viruses, and sporocidal if in contact with spores for at least 15 minutes

Why is it a good idea to scrub the skin with alcohol before using iodine?

because the presence of organic material makes iodine less effective

What are the "pros" of steam sterilization/autoclaving?

cheap; non-toxic, safe, and simple to use; effective; can be used for both wrapped and unwrapped items; quick turnaround time

Define antiseptic.

chemical agent that reduces microbial load or inhibits growth of microbes on living things/animate objects (like skin scrubs!)

Define disinfectant.

chemical agents that reduce microbial load on an inanimate object

Describe chemical sterilization indicators.

chemical change occurs in response to heat, pressure, and/or humditiy but NOT exposure time; these DO NOT confirm sterility

Sterilization indicators can be ________ or __________.

chemical or bioogical

You can clean things without sterilizing, but you cannot sterilize things without ________.

cleaning

This method of sterilization uses liquid chemicals that are non-corrosive. Chemical used include glutaraldehyde and hydrogen peroxide. Disinfection takes 10 minutes but sterilization takes 10 hours.

cold chemical sterilization

What are the three levels of sterility/disinfection?

critical, semi-critical, and non-critical Note that there is no gray area when it comes to something being sterile - it is etiher sterile or it isn't

Describe providone iodine (PVI) as an antimicrobial agent.

disinfectant and antiseptic; bacteriocidal, fungicidal, effective against viurses, and effective against spores if contact time is at least 15 minutes; minimal residual activity; effectiveness decreases with presence of organic material (which is why skin is also usually cleaned with alcohol); concentration varies according to its use; 0.1-1% for wound management; 10% for pre-surgical preparation

Describe isopropyl alcohol (IPA) as an anti-microbial agent.

disinfectant and antiseptic; bacteriosidal at high concentrations, bacteriostatic at lower concentrations; kills many fungi and viruses; not effective against spores; minimal residual activity because of evaporation; considered less effective than PVI or CHG; helpful in removing excess lipids on the skin prior to surgery

Define sterilization.

elimination of all microbes on an inanimate object

Describe the non-critical level of disinfection.

equipment that comes in contact with intact skin or mucus membranes but is not directly associated with surgery; includes laryngoscopes, stethoscopes, u/s probes, BP cuffs, ECG leads, pulse ox, and exam tables; these items should be disinfected but do not require specific handling between patients; note thee should be terminally cleaned when done for the day

This method of sterilization is good for heat-intolerant, and moisture intolerant items including plasics, endoscopes, power cables, and cameras. A major con of this method is that it is very toxic.

ethylene oxide/gas sterilization

What are some cons of ionizing radiation used for sterilization?

expensive; dangerous; can cause breakdown of packaging material or product

What are some pros and cons of using laminated sleeves/puches as part of a surgical pack?

pros - they are cheap and easily obtained; can visualize items inside; there are pre-cut sizes or rolls in various widths, and several small items can fit in them cons - easily perforated when wet and heavy items can break through them

What are some "low level" areas of contamination in an animal hospital?

reception desks, offices, walls, and doors

Define disinfection.

reduction or destruction of most pathogenic microorganisms on inanimate (non-living) objects

Describe the residual activity of CHG.

residual activity due to keratin binding; NOT inactivated by organic debris, alcohol, or soaps

Paper bags are good for wrapping small ites such as cotton balls and gauze. What are some pros and cons of using paper bags as wrapping material as a part of a surgical pack?

they are cheap and easy to obtain, but easily perforated when wet, do not allow for visualization of contents, and heavy items can brekathrough them

Describe biological indicators of sterility

they are the only means of ensuring sterility; assessed bysing bacteria maintained in a broth or on a strip

Describe the critical level of disinfection

this includes equipment or implants that are entering the body, sterile tissue, cavity, or bloodstream; surgial instruments, surgical implants, suture material and catheters fall under this critical level; all items must be STERILE

Describe the semicritical level of disinfection.

this includes equipment that comes in contact with the skin or mucus membranes without penetrating into the body or cavities; colonoscopes, endoscopes. ET tubes, anesthetic equipment, and vaginoscopes fall into this semi-critical level of disinfection; items must be cleaned and disinfected to reduce microorganisms, but since sterility is not maintained during procedure sterility is not required; terminal sterilization is common

Describe gas sterilization.

use of ethylene oxide that diffuses through to sterilize something; EtO is toxic and flammable, and this process takes a long time; efficacy of gas sterilization depends on gas temperature, humidity, and exposure time

Descrine ionizing radiation.

use of gamma radiation; low temperature sterilization; useful for heat-sensitive equipment; only commercial use because it is so expensive; uses cobalt 60 gamma rays

Describe plasma sterilization.

use of hydrogen peroxide (H2O2); low temp sterilization; rapid and no drying needed; uses UV photons and radicals; kills microorganisms by oxidation

What are some things to consider when selecting a disinfectant?

which level of disinfection is required (critical, semicritical, non-critical); if the disinfectant is compatible to the item that you want to disinfect; if the disinfectant is user-friendly; if the disinfectant is cost-effective

Describe gravity dislpacement steam sterilizers.

works on the principle that air is heavier than steam; pressurized steam goes from the outer chamber to inner chamber of the machine; gravity displacement steam sterilizers are relatively cheap, simple to use, and dependable

What type of sterilization method is best for items with hard-to-reach spaces that need to be sterilized?

pre-vacuum steam sterilization

What are the types of steam sterilizers?

Gravity displacement, pre-vacuume sterilizer, and flash sterilizers

What disinfectants/antiseptics are affective against viruses?

IPA and PVI are both effective against viruses; CHG is a poor defense against viruses; alcohol-based solutions may or may not be effective against viruses (the same is true in terms of the disinfectants/antiseptics and fungi)

What disinfectants/antiseptics are affective against spores?

PVI is the only one that is always effective against spores; alcohol-based solutions may or may not be effective against spores; IPA and CHG are not effective against spores

This method of sterilization involves full liquid immersion and there is no long-term storage option for instruments sterilized this way.

Paracetic acid sterilization

This method of sterilization is done at a low temperature. It kills microorganisms by oxidation but it does not have a very good penetrating power.

Plasma sterilization (which uses hydrogen peroxide)

What are the four major disinfectants and antiseptics?

isopropyl alcohol (IPA); providone iodine (PVI); chlorhexidine gluconate (CHG); and alcohol-based solutions

What are the cons of chemical/gas sterilization with ethylene oxide?

it is expensive, takes a long time, and is very hazardous!

What are some high-level areas of contamination in an animal hospital?

kennels/housing, exam tables, operating tables and floors

Define sterility.

absence of all forms of microbial life; ONLY on inanimate objects

Describe steam sterilization.

aka autoclaving! - saturated steam destroys microorganisms by coagulation and denaturation of cellular proteins; cleans items that are both heat and moisture-resistant

Describe pre-vacuum sterilizers.

allows sterilization in harder to reach spaces through a vacuum mechanism; this method of sterilization is good for porous items with hard to reach spaces

Describe flash sterilization.

another method of steam sterilization; should be used in emergencies only; uses gravity displacement sterilizer; this sterilization technique has a higher risk of contamination

Describe chlorexidien gluconate (CHG) as an antimicrobial agent.

antiseptic; rapid bacteriosidal activity; minimal effectiveness against viruses or fungi; not sporocidal; high residual activity due to keratin binding; NOT inactivated by organic debris, alcohol, or soaps; .05% concentration used for wound management; 4% used for surgical preparation

Describe alcohol-based solutions in terms of anti-microbial activity and use for surgery.

antiseptics; usually made up of a combination of things so that it acts quicker and has a slightly longer residual activity; superior antimicrobial activity than CHG, PVI, or IPA alone; more residual activity than alcohol alone; is a one-step, "scrubless" process

What are some pros of ionizing radiation for sterilization?

gamma rays have high penetrating power; rapid; low temperature; flexibility

What are some cons of plasma sterilization?

gas cannot penetrate linen, gauze, wood, endoscopes, and some plastics; plasma sterilization requires specific synthetic packaging; sterilization chamber is relatively smaller than that of an ethylene oxide sterilizer

What are the pros of gas sterilization (with ethylene oxide)?

gas sterilization with ethylene oxide is good for objects that are sensitive or intolerant to heat and/or moisture

What are some reasons for failure of steam sterilizers?

inappropriate packaging or loading; poor steam quality; vacuum failure; or inadequate temperature

This method of sterilization is done at low temperature and is good for heat-sensitive items, but it is expensive and dangerous so it is usually only done commercially.

ionizing (gamma) radiation

This disinfectant/antiseptic is considered less effective than PVI and CHG.

isopropyl alcohol (IPA)

This disinfectant/antiseptic is useful in removing excess lipids from the skin prior to surgery.

isopropyl alcohol (IPA)

What disinfectants/antiseptics are affective against fungi?

isopropyl alcohol (IPA) and povidone iodine (PVI) are both affective against fungi; chlorexidine gluconate (CHG) is a poor defense against fungi, and alcohol-based solutions may or may not be effective

What disinfectants/antispetics are affective against bacteria?

isopropyl alcohol (IPA), povidone iodine (PVI), chlorhexidine gluconate (CHG), and alcohol-based solutions are all affective against bacteria; it is noted that PVI and CHG act against bacteria quickly

Describe paracetic acid sterilization.

low temperature liquid immersion sterilization; good for heat sensitive items but only for immediate use - there is no storage option

Describe cold sterilization.

non-corrosive liquid chemical sterilize instrunments; effect depends on contact (immersion) time; disinfection requires 10min while sterilization requires 10hours; chemicals can include glutaraldehyde, ortho-phthalaldehyde, or hydrogen peroxide; instruments should be rinsed with sterile water and dried with a sterile towel after cold sterilization

What are the cons of steam sterilization (autoclaving)?

not suitable for heat sensitive items; potential for injury if not used or maintained correctly (burn), requires care and maintenance

What are some cons of paracetic acid sterilization?

only applicable for immersible instruments; can be expensive; no sterile storage option - instruments must be used right away

Plasma sterilization kills microorganisms by _________.

oxidation

List the common wrapping materials used for surgical packs.

paper bags, linen material, synthetic material, laminated sleeves/puches/packs, and aluminum or stainless steal instrument containers

After which sterilization method do instruments have to be used right away?

paracetic acid sterilization

Describe preparation of a surgical pack.

place and oragnize instruments, add drape and gauze, add sterile indicator, wrap 2x, secure with autoclave tape, sign, initial, and date

What is listed as the number one method of sterilization of heat and moisture-sensitive items?

plasma sterilization

Which is generally considered a more effective anti-microbial agent - isopropyl alcohol or povidone iodine?

povidone iodine

This is the most common method of sterilization and is used for heat and moisture-tolerant items. It does require some maintenance.

steam sterilization - autoclaves!

List the major sterilization methods.

steam sterilization, chemical (gas) sterilization (with EtO), plasma sterilization (gas sterilization with hydrogen peroxide gas), paracetic acid sterilization, ionizing radiation (with gamma rays), and cold chemical sterilization

What are the pros of plasma sterilization?

sterilizes heat and moisture intolerant items (this is the best option for these items); quick turnaround time; there are no harmful emmissions

What are the pros of paracetic acid sterilization?

sterilizes items that do not tolerate heat; rapid cycle; low temperature; safe