Hygiene III

Mark D. SobseyENVR 890-2Spring, 2009

Handwashing with soap after toilet/cleaning child

• Burkina 1% and 13% • Ghana 4% and 2%• Nigeria – and 10%• Brazil – and 16% • Peru 6% and 30%• Kyrgyzstan 18% and

0%• N. England 80% and

47%

In the last 10-15 years hygiene has moved up the health agenda

What has brought about the change ?• Infectious disease tends have increased for some agents• Food borne disease remains at unacceptably high levels• Person-to-person tranmsission is now seen a significant

cause of spread of infectious intestinal & respiratory diseases• Antibiotic resistant strains - need to prevent spread• Viral agents - not treatable with antibiotics• Ongoing emergence of new hazardous agents, e.g SARS

• “at risk” groups in the home and community: – elderly, very young, immune-compromised – up to 1 in 7 people in US belong to an “at risk” group

Good hygiene practice is key to reducing these risks - in many cases the first line of defence

Trends in Gastrointestinal Infections in England and Wales

• Increases in the 1990s

• Campylobacter and Salmonella

• Increases in rotavirus illness

• Suspected increases in viral etiologies like Noroviruses

What Proportion of Gastrointestinal Infections Occurs in the Home?

• Estimates of 50-80% in Europe• Sources and causes:

– Inappropriate hygiene practice• Failure to wash hands• Failure clean high-risk areas

– Domestic pets– Viruses, enteric and respiratory– Flies and other insect vectors

Infectious Disease Risks in the Home

• Pathogen contamination is highest in the kitchen, bathroom and in the washing machine

• Routine activities in these areas facilitate microbial spread and transmission

• Commercial cleaning products vary in their efficacy in reducing pathogens

• Product misuse undermines efficacy• Behavior of consumers is a big factor in

pathogen spread and behavior change though education and communication is a challenge

Environmental Contamination and Infectious Disease Transmission

• Contact transmission, direct from body surface to body surface or indirect transmission via contaminated inanimate object, are main routes of microorganism (pathogen) transmission

• Pathogens are on inanimate objects• They persist for days to weeks• Pathogens on inanimate objects in the

environment can be transferred to hands/fingers and other parts of the body

• Pathogens are on inanimate objects in the environment and are a source of transmission causing infectious disease

• Environmental (e.g., surface) disinfection reduces pathogens and disease risks

Dried MS2 virus infectivity at 25oC on stainless steel and ceramic tile

Effect of Different Cleaning Methods on Norovirus Presence on Surfaces

• Melamine surfaces contaminated with NV in feces, diluted 1:10 or 1:80 in PBS

• Detergent cleaning, even with 2nd wipe step, failed to decontaminate surfaces

• Virus was spread to a clean surface and fingers via a wiping cloth in all but one case (transfer to fingers from most lightly contaminated surface)

• Surface treated with HDC (5000 ppmavailable chlorine) for 1 min reduced NV completely

• No-cross-contamination, except for one of the surfaces, which had the heavier soiling

Evaluation of Hand Hygiene Methods and Agents:

• Contaminate hands with bacteria and virus

• Clean hands for 10 seconds by washing, wiping or rubbing methods

• Test different cleaning agents• Recover microbes from hands

(glove juice method)• Repeated challenges and

recoveriesSickbert-Bennett, E.E., Weber, D.J., Gergen-Teague, M.F., Sobsey, M.D., Samsa, G.P.,Rutala, W.A. 2005 “Comparative efficacy of hand hygiene agents in the reduction of bacteria and viruses,” Amer. J. of Infection Control 33(2):67;

Efficacy of Hand Hygiene Agents: Log10 Reductions of S. marcescens after 1 and 10 Challenges

(A) 60% ethyl alcohol; (B) 61% ethyl alcohol; (C) 62% ethyl alcohol; (D) 61% ethyl alcohol/1% CHG; (E) 70% ethyl alcohol/0.005% silver iodide; (F) 0.4% benzalkonium chloride; (G) 0.5% PCMX/40% SD alcohol; (H) 0.75% chlorhexidine gluconate; (I) 2% chlorhexidine gluconate; (J) 4% chlorhexidine gluconate; (K) 1% triclosan; (L) 0.2% benzethonium chloride; (M) nonantimicrobial control; (N) tap water control.

Your parents were right: “Wash Your Hands!”

Efficacy of Hand Hygiene Agents: Log10 Reductions of Coliphage MS2 after 1 and 10 Challenges

(A) 60% ethyl alcohol; (B) 61% ethyl alcohol; (C) 62% ethyl alcohol; (D) 61% ethyl alcohol/1% CHG; (E) 70% ethyl alcohol/0.005% silver iodide; (F) 0.4% benzalkonium chloride; (G) 0.5% PCMX/40% SD alcohol; (H) 0.75% chlorhexidine gluconate; (I) 2% chlorhexidine gluconate; (J) 4% chlorhexidine gluconate; (K) 1% triclosan; (L) 0.2% benzethonium chloride; (M) nonantimicrobial control; (N) tap water control.

Your parents were right: “Wash Your Hands!”

Summary of Hand Hygiene Results• At a short time (10 sec.), all agents but handwipes and 60% ethyl

alcohol handrub were similar to non-antimicrobial and tap water controls• Reductions of 1.15 to 2.0 log10 of Serratia marcescens• After 10 episodes (multiple episodes of contamination) handwashing

agents with 0.75-4% CHG, 1% triclosan, 0.2% benzethonium chloride, nonantimicrobial soap handwash, and tap water alone were efficacious (>1.5 log10) in reducing bacteria

• Only some effectively reduced viruses: water, soap, benzethonium Cl, and CHG, and CHG effectiveness declined greatly by 10 challenges

• Alcohol-based handrubs and wipes were ineffective for virus reduction• Short contact times are effective in reducing transient hand flora

– So, focus hand hygiene on improving compliance rather than increasing the duration of hand hygiene.

– If shorter duration of hand hygiene improves compliance, greatercompliance should lead to reduced infections.

Hand Hygiene at the Community Level• Minimum effect of a single handwash

with either plain or antimicrobial soap on the quantity of hand microflora

• After 1 year, significant reduction of hand microflora counts by use of either soap

• Sustained and consistent hand hygiene significantly microbial loads over time

• Effects of handwashing on hand microflora may not be predictive of the effects on pathogen reduction or disease reduction

Aiello AE, Marshall B, Levy SB, Della-Latta P, Larson E. (2004) Relationship between triclosan and susceptibilities of bacteria isolated from hands in the community. AntimicrobAgents Chemother. 2004 Aug;48(8):2973-9

Comparison of mean pre-and post- handwash CFU counts between groups using antimicrobial (AM) or plain soap. N = about 200

Developing a rational approach to home hygiene

- a risk-based approach

Based on material from a Powerpoint by Sally Bloomfield

London School of Hygiene and Tropical Medicine

A risk assessment approach to home hygiene

• In recent years the concept of HACCP (Hazard Analysis Critical Control Point) - identifying critical points and targeting hygiene at these risk points has successfully controlled microbial risks in food and other manufacturing environments

• To devise a hygiene policy which has real health benefits it is accepted that a risk-based approach must also be developed for the home

IFH approach to home hygiene

– For IFH the “risk assessment” or HACCP approach to home hygiene has come to be known as the “targeted hygiene”

– “Targeted hygiene” mean identifying situations where there is a significant risk of spread of harmful microbes, and intervening at the appropriate time to prevent spread

Developing a risk assessment approach to home hygiene

Pathogens (or potential pathogens) are introduced continually into the home via:

people, food, pets, water, insects

Also - sinks, sink and basin U-tubes, toilets, wet cleaning cloths can support growth of harmful microbes (mainly opportunist but also some primary pathogens) and become a primary source of infection.

Developing a risk assessment approach to home hygiene

To be effective home hygiene policy based on risk assessment must consider:

Hazard identification including dose response assessment

- probability of contamination c. harmful microbes- infective dose

Exposure assessment- probability of transfer/cross contamination- such that human exposure could result

Risk approach to hygiene in the domestic setting

Site(s)

Chance of germs being

present

Risk of

spread of germs

Assessment of need for a

hygiene procedure

• Reservoirs (Toilets, U-tubes, etc)

Highest

variable Relatively little except where known high risk (e.g. Shigella outbreak)

• Reservoir/dissemin-ators (wet cloths & cleaning utensils)

Highest

Constant

Always

• Hands Sometimes Constant Always` • Hand, food, water

contact surfaces Sometimes

Constant Always

• laundry Sometimes Occasional Known high risk • Floors, walls, etc

Low

Occasional Relatively little except where known risk

spillage)

• Good hygiene is not about “creating a germ free home” but about identifying high risk sites and situations and targeting hygiene measures appropriately (i.e as and where necessary) to reduce exposure to microbes which could be harmful

Hygiene procedures in the home- reducing the risks

What do we mean by “hygienic cleaning”

• The purpose of a hygiene procedure (hygienic cleaning) is to reduce microbial contamination on a surface (hands or other surface or site) to a level which is not harmful to health

What do we mean by “hygienically clean”

“a level of germs which is not harmful to health”But• infectious dose varies:

– viruses: 1-100 particles– bacteria: may be 10 --> as high as 106

– Salmonella: amplified following transfer to food• depends on the susceptibility - may be lower for “at

risk” groups• Without precise data it seems reasonable that :

– where there is significant risk of germs spreading (e.g. during food preparation)

– aim should be to get rid of as many germs as possible

What methods are available for “hygiene cleaning”

• A hygienically (as opposed to visibly) clean surface is achieved either by removal of microbes or application of a disinfection process or a combination of both:

What methods are available for “hygiene cleaning”

Detergent-based hygienic cleaning• In many situations - hands, cooking/ eating utensils, hygiene

achievable using detergent-based cleaning. • To be effective it must be applied in conjunction with a thorough

rinsing process - to wash germs away from the surfaceDisinfection• Alternatively “germ kill” can be used

- chemical disinfectant products- heat (e.g boiling or >60°C)

or: Combined removal and kill- laundry - removal, heat and bleach kill- dishwashing - removal, heat kill

•Can you “wash” the germs away?– Large surface, taps, biofilms ?

•Have you washed the germs away?– “In homes” studies suggest that this is sometimes not the

case - in some situations e.g food hygiene the extra margin of safety from use of disinfectants is advisable

•Where have the germs gone ?– Contaminated water, particularly c. a cloth is highly effective

means of spreading pathogens

In deciding whether “soap and water” is the appropriate hygiene procedure or whether a disinfectant is needed - need to consider:

Percentage of sites contaminated with

Salmonella and/or Campylobacter

No of participants in each group = 20

After Meal Preparation

After Cleaning with Soap and

Water

Soap and water +

hypochlorite

Chopping bd 60 15 0 Utensils 5 25 5 Hands 35 20 0 Dishcloth 25 25 5 Taps 5 25 0 Sink 30 30 0 Sink Rim 10 15 5 Fridge Door 10 10 0 Cupboard 10 5 5 Oven Door 10 10 0 Kitchen Door 10 10 0 Condiments 5 5 0 TOTAL 17.3 15.3 2.3

Cogan, Bloomfield and Humphries, Letters in Appl.Microbiology 1999, 29,354-358

Food hygiene - risks associated with preparation of a meal using a chicken contaminated with Salmonella or Campylobacter

UK data indicates:

• 25% and 83% of raw chickens contaminated c.Salmonella and Campylobacter(Jorgensen et al. 2002).

• Every day 1 in 25 homes prepare a meal with a Salmonella and/or Campylobacter-contaminated chicken

• 0.4% and 0.8% of beef & lamb products from retail butchers are +ve for E. coli O157 (Chapman et al. 2001)

General hygiene - effectiveness of hygiene procedures in eliminating norovirus from surfaces (N = 14)

Barker, Vipond and Bloomfield, J. Hospital Infection 2004, 58, 42-49

Surfaces soiled with faeces/norovirus

Contaminated cloth used to wipe a clean surface

Key concepts of targeted hygiene

• Current concept of home hygiene:– People still largely see home hygiene as a

process of "getting rid of household germs" -believing that this is the appropriate means to protect their family against infection.

• we need to promote the concept of “targeted hygiene”– identifying a microbes, and intervening at the

appropriate time in appropriate manner to prevent spread

Key concepts of targeted hygiene

• In the places and at the times that matter it is important to not just clean but “hygienically clean”– can be achieved by detergent based cleaning,

provided this is through and accompanied by adequate “rinsing” process

– within a targeted hygiene approach - in some situations it is advisable to disinfect

Targeted hygiene is simpler - and healthier

• “Targeted” hygiene offers the means to deliver messages which make sense to consumers

• It offers the means to maximise protection against infection whilst reducing the impact on our human and natural environment to the least extent

Education is the key factor

Targeted hygiene

www.ifh-homehygiene.org

IFH guidelines on home hygiene IFH teaching/self-

learning materials on home hygiene

Further Reading - IFH reviews, consensus views, Guidelines, training resources etcBiocides and resistance• Microbial resistance and biocides: a review and consensus statement

http://www.ifh-homehygiene.org/2003/2public/2pub03.aspHygiene Hypothesis• The Hygiene hypothesis and its implications for hygiene. http://www.ifh-

homehygiene.org/2003/2hypothesis/hh.htmTargeted approach to home hygiene• Bloomfield, S.F. (2002) Home hygiene: a risk based approach. International

Journal of Hygiene and Environmental Health, 205, 1-8IFH guidelines and teaching materials• Guidelines for prevention of infection and cross infection the domestic

environment. http://www.ifh-homehygiene.org/2public/2pubgu00.htm• Recommendations for selection of suitable hygiene procedures for use in

the domestic environment.http://www.ifh-homehygiene.org/2public/2pub04.htm

• Home Hygiene - prevention of infection at home: a training resource for carers and their trainershttp://www.ifh-homehygiene.org/2003/2public/2pub06.asp