A Summary
The NHS Executive has provided detailed, evidence-based guidance for the sterilisation of infected hospital laundry. This is in the knowledge that many pathogenic microbes have demonstrated an ability to survive laundry processes that fall below the recommended programme of autoclaving (pressurised steam cleaning) and / or thermal (hot water) disinfection, high volume water rinses and chemical disinfection. 1,4,5,6,7
Outside of the hospital environment there are a number of troublesome skin infections that have the potential to be spread through contact with infected laundry and thereby cause re-infection of the original sufferer or cross-infection of other individuals who share towels, bed linen or even just a laundry basket with the infected person.
Domestic washing machines are not capable of reaching the appropriate temperature, for a long enough time period to ensure thermal disinfection. In addition, domestic washing machines do not provide sufficiently large volumes of rinsing to assist in reducing infection loads in the wash. Finally modern, dyed fabrics are not able to withstand the hypochlorite bleaching rinses that could offer a final line of defence against infection through domestic laundry.
There is therefore an opportunity for a proven, anti-microbial, disinfectant laundry product to sterilise the home wash and break the cycle of re-infection and cross-infection that undermines the use of over-the-pharmacy-counter topical antifungal and antibacterial treatments for common skin infections. That product is ERADICIL.
National Health Service Hospital Laundry Guidelines – the minimum requirements to disinfect laundry
In recent years healthcare providers have come under great pressure to review their infection control guidelines in order to limit the increasing illness and death associated with hospital-acquired infections, most notoriously by germs such as methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile. In order to ensure that clothes, towels and bed linen that are soiled with potentially harmful germs can be reused safely in the hospital environment, the National Health Service Executive (NHSE) has devised and laid down guidance for the laundering of used and infected linen.2 This guidance, last updated in April 1995, ensures that harmful germs are killed and that the resulting sterilised linen can be reused without the risk of harbouring infection that could be passed on to subsequent users of the laundered items. Clearly this guidance offers a 'gold standard' of infection control for the domestic laundry situation when any members of the household are carrying a skin infection that is transmissible, either by re-infection or cross-infection, by soiled laundry items (see Conclusions, below). However it is far from practical for the home!
The main features of the NHSE Guidelines for soiled, foul and infected items are as follows:-
- Items known to be contaminated with pathogenic or other hazardous organisms must be steam-sterilised by autoclaving (effectively a type of steam pressure cooker) before laundering in order to guarantee complete disinfection.
- Laundry disinfection (of soiled, foul and previously-autoclaved infected items) must be carried out utilising a thermal disinfection cycle in which the temperature of light laundry loads (i.e. those below 560 grams per litre of main wash) are maintained at 65°C (150°F) for not less than 14 minutes or preferably at 71°C (160°F) for not less than 7 minutes. In order to assure disinfection an additional "mixing time" of 8 minutes should be added to these times for loads above 560 grams per litre.
- The temperatures used in the thermal disinfection cycles are so critical that the Guidelines call for new washing machines to be tested on commissioning and re-tested at 6-weekly intervals to ensure that the heat sensors are maintained and calibrated appropriately. Domestic washing machines are not permitted in health care environments.3
- The recommended thermal disinfection temperatures should be sufficient to inactivate most harmful germs including the Human Immunodeficiency Virus (HIV) however there is some uncertainty as to the minimal temperature required to inactivate the hepatitis B virus. Thus the NHSE Guidelines call for a combination of thermal disinfection and "the considerable dilution factor stage" available in commercial-scale laundry machines in order to render the linen safe to handle on completion of the wash cycle.
- The use of 'heat-labile' fabrics (those that would be damaged by laundry temperatures above 40°C (104°F) are discouraged in the healthcare environment since they are unable to withstand the rigours of thermal disinfection at 65°C (150°F). Nevertheless the Guidelines take account of the need for a non-thermal disinfection of staff uniforms and patients' clothing through the use of hypochlorite bleach. Uniforms or work clothes should be washed as soon as possible on as hot a wash as the fabric will tolerate (65°C is recommended for thermal disinfection but most domestic machines only wash at 60°C and most clothes have a label recommending washing at 40°C).3
- The Guidelines warn that the performance of hypochlorite bleach as a disinfectant is often restricted by the presence of soiling, detergents and alkalis in the wash. Nevertheless the addition of bleach is recommended, at a minimum hypochlorite concentration of 150 parts per million for a minimum duration of 5 minutes, in a penultimate rinse, if this can be achieved without overriding the washing programmes of the machine.
Domestic Laundry and Disinfection
Modern domestic washing machines are manufactured to the primary design criteria of ease of programming, minimal use of water and energy-consumption efficiency. Washing powder manufacturers strongly market detergents that can launder at low wash temperatures, below 40°C (104°F), to suit the new generation machines and as a response to consumer demands to be more eco-friendly and to consume less energy.
Typical domestic machine programme washing times are of 30 to 40 minutes duration, (excluding the rinse and spin cycles) compared to standard hospital loads which take 80 to 100 minutes. Clearly this does not allow sufficient time for even a small wash to reach and be maintained at disinfection temperatures for long enough, even if a 95°C (202°F) "boil wash" programme is selected.
The concomitant use of bleach that would enable a sub-40°C (<104°F) temperature wash to reduce microbial counts in fabric5 is not used in the domestic laundry situation since it would remove dyed fabric colouration and cause unacceptable material damage and an unpleasant, residual chemical smell to the washed items.
Stain removal, fabric softening and a pleasant fragrance, rather than disinfection, have become the primary objectives of the modern home wash. Under normal circumstances this is not a problem, but when the laundry basket contains socks, towels, bed linen and underwear that harbour high concentrations of pathogenic bacteria or fungi from topical infections such as: athlete's foot, vaginal thrush, fungal nail, impetigo, ringworm or jock itch, the opportunistic cycle of cross-infection and re-infection can flourish. It has long been known that infected skin scales from individuals can survive normal laundry procedures to infect other individuals.6 The communal use of towels and socks has long been known to be the most important factor in the spread of athlete's foot7 and has also been recently implicated in spread of Community-Acquired MRSA within sports teams.8
1 Gentles JC, Evans EGV. Foot infections in swimming baths.BMJ 1973;3:260–262
2 Health Service Guidelines. Hospital laundry arrangements for used and infected linen. NHS Executive HSG(95)18. 21st April 1995
3 Infection Prevention and Control Policy. South West Essex Primary Care Trust (July 2007) available here: http://www.swessexpct.nhs.uk/documents/general/Infection Prevention Policy pdf.pdf
4 Mortimer Davis Jewish General Hospital, USA
5 Smith JA, Neil KR et al. Effect of water temperature on bacterial killing in laundry. Infect Control 1987;8(5):204-9
6 Broughton R. Reinfection from socks and shoes in tinea Pedis. Br J Derm. 1955;67:249-54
7 English MP, Wethered RR, Duncan EHL. Studies in the epidemiology of tenea pedis. Br Med J. 1967; 3:136-9
8 Romano R, Lu D, Holtom P. J Athletic Train. 2006;41(2):141-5