Healthy Population Block 2 Cleaning and Disinfection

factors contributing to disease

1. environmental disinfection

2. hand hygiene contact precautions

3. antimicrobial stewardship

4. animal procedures/movement/source

5. identification of infected or colonized patients

How do environments play a role in disease

1. dirty/contaminated environments can act as reservoirs for pathogenic disease spread

2. increased environmental contamination results in increased hand contamination

3. housing in areas previously occupied by patients with pathogen is risk factor for disease

4. improved surface cleaning and disinfection reduces disease incidence

How are environments contaminated

1. individual bacteria can latch on to environmental surfaces and recruit other bacteria

2. makes community, biofilms

biofilms

1. biofilms are resistant to common methods used to reduce bacterial contamination

2. robust extracellular matrix and inner core protect community

3. shear stress, antibiotics, disinfectants have difficulty completely removing biofilm

What do you do first?

Clean!

cleaning definition

removal of visible, foreign material using soap, water, and mechanical stress

how does cleaning work

1. cleaning removes 90-95% of pathogens, including highly resistant pathogens

2. removes organic matter that decreases effectiveness of disinfectants

steps for cleaning

1. dry cleaning

   1. removal of gross debris

   2. moisten debris to prevent aerosolization

2. washing

   1. warm/hot water and detergent

   2. use steam for cracks and crevices

   3. pressure wash

3. rinsing and drying

   1. cold water, low pressure

   2. be aware of runoff

   3. dry surfaces completely before disinfection

What is in a detergent?

1. surfactant molecules that break up debris

2. hydrophobic tail penetrates oily dirt

3. hydrophilic head allows dirt to be lifted in water

4. enzymes can breakdown fat, proteins, and other organic material

desired characteristics for detergents

1. readily soluble in water

2. effective in softening water

3. noncorrosive and nontoxic

4. economical/budget friendly

5. stable solution

saponification

convert fats and oils into soap so they can be suspended in water

peptization

breakdown proteins into solution

what should detergent do

1. saponification

2. peptization

3. dissolve minerals into solution

Anionic/neutral and alkaline detergent

1. better at emulsifying, lifting, and dispersing debris

2. less foam production

3. most detergents

acidic detergents

1. good for removing mineralized material

2. corrosive and toxic

3. frequently used on equipment

factors affecting detergent efficacy

1. water hardness

2. pH

how does water hardness affect detergent efficacy

1. hardness is amount of dissolved Ca and Mg dissolved in water

2. hardness >85ppm will neutralize detergents

3. softeners might need to be added

How does pH affect detergent efficacy?

acids and bases can interfere with detergent efficacy

disinfection

destruction/inactivation of pathogenic microorganisms (not spores) on inanimate surface

antisepsis

destruction/inactivation of pathogenic organisms on living tissue

sterilization

destruction/inactivation of all forms of microbial life, including endospores, on inanimate objects

sanitization

general act of reducing microbial load to safe level

what is important before disinfection

surface must be completely dry before disinfection

log reduction targets

1. non-food sanitizers >=3 log reduction

2. general disinfectants >=4 log reduction

3. hospital disinfectants >=6 log reduction

disinfection methods

1. physical

   1. desiccation

   2. heat

      1. dry

      2. moist

   3. UV

2. chemical

   1. oxidation

   2. hydrolysis

   3. denaturation

   4. substitution

concentration influences efficacy

determines -static vs -cidal effect

application method influences efficacy

surface application vs soaking vs fumigation

contact time influences efficacy

most critical, often overlooked

most require about 10-15min of contact time (wet) for maximal efficacy

stability and storage influences efficacy

best to store undiluted in cool, dry, dark place and monitor expiry dates

organic load influences efficacy

physical barrier that inactivates most infectants

water hardness influences efficacy

can form complexes with disinfectants that lead to residues

temperature and humidity influences efficacy

warmer environments are generally better; too warm or dry increases evaporation

pH influences efficacy

effect depends on product

pathogen type influences efficacy

1. susceptibilty

2. stability

3. biofilm formation

pathogen abundance influences efficacy

1. killing occurs at specific rate

2. higher starting # = higher ending #

surface type influences efficacy

smooth, non-porous surfaces are easier to disinfect

factors to consider with selecting a disinfectant

1. toxicity to staff and patients

2. irritation to staff and patients

3. is it corrosive

4. smell 

5. cost

label contains

1. limited efficacy: gram + or gram -

2. broad spectrum/general purpose: gram + or gram -

3. hospital or medical environment: gram + or gram -

aldehydes advantages

1. broad spectrum

2. sterilized

aldehydes disadvantages

1. carcinogenic

2. causes irritation to mucous membranes and tissue

3. PPE is required for use

aldehydes notes

1. ex: formaldehyde, glutaraldehyde

halogens advantages

1. broad spectrum, non-enveloped viruses

2. low cost

halogens disadvantages

1. no cleaning properties

2. inactivated by sunlight and organic matter

3. corrosive

4. irritation

halogens notes

1. never mix with acid or ammonia b/c makes chlorine gas

2. should be diluted 1:32 with cold water

3. needs to be made fresh every 24 hrs

4. ex: bleach

oxidizing agents advantages

1. broad spectrum

2. some detergent activity

3. long shelf-life once mixed

oxidizing agents disadvantages

1. somewhat corrosive

2. expensive

oxidizing agents notes

1. good choice especially for high-risk areas like isolation, ICU

2. ex: accelerated H2O2, trifectant

substituted phenols advantages

1. broad spectrum

2. active in hard water

3. active in presence of some organic material

4. residual

substituted phenols disadvantages

1. limited activity on non-enveloped viruses

2. skin irritation

3. potential toxicity

substituted phenols notes

1. ex: lysol, one stroke

quaternary ammonia compounds advantages

1. reasonable spectrum

2. low cost

3. some detergent activity

4. odorless, colorless, non-irritating

quaternary ammonia compounds disadvantages

1. not effective against non-enveloped viruses

2. inactivated by many soaps

quaternary ammonia compounds notes

1. ex: virex, diquat, zepharin

common mistakes for disinfectants

1. inadequate contact time

2. not diluting disinfectant properly

3. not rinsing disinfectant

4. cross contamination

5. using footbaths

6. using pressure hose on infectious material

7. selecting disinfectant that doesn’t match your C&D goals