Controlling odours and micro-organisms

Over the last five years the media has regularly reported incidents and even deaths caused by outbreaks of MRSA and clostridium difficile (C.diff) in the healthcare sector. Every summer, bacillus cereus re-appears and causes acute local problems until it is dealt with.
However, there are now signs that, additionally, the hospitality sector is now paying much more attention to textile disinfection. Increasingly launderers are required to address potential problems with micro-organisms on "clean" linen, even though no infection outbreaks have yet been linked to laundered linen.
Still customer expectations will have an impact and laundries need to deal with potential problems and risks efficiently and effectively.

Odours
Most objectionable odours in the healthcare sector can be linked directly to bacteria breeding on soiled textiles, producing foul-smelling "excrement".
The worst sewer-type smells are generated by human body fluids, particularly faeces. This is because coliforms (particular groups of micro-organisms in the human gut) give off odours that the human nose finds particularly offensive. The reason why some nursing homes smell so much worse than others is attributed at least in part to the percentage of washes that are designed to give disinfection.
If foul sheets are processed with a main wash at 40C, then there are around 107 - 108 coliforms on the textile surface and a low temperature process will not reduce these sufficiently. The surviving bugs will breed on the remaining soiling and within 24 hours the sheet will stink again.
A higher temperature, say 75C, would give a better result as it will cause the yarns to swell and open up to release more of the soiling so it can be removed. The low temperature leaves more soiling nutrient for bugs to feed off and so the problem continues.
Both machine makers and chemical suppliers have responded by developing solutions. Some washers now treat the water with disinfectant at every wash stage. Ozone has been found to be particularly effective. Ozonated water will kill a range of micro-organisms, provided the concentration is correct throughout the wash and rinse stages. It is poisonous if it gets into the laundry air but simple safety measures will avoid this risk.
Trials at 40C have not only reduced the degree of vegetating bacteria but also significantly reduced spore formers such as clostridium difficile.
Most chemical suppliers now offer detergents or additives for thermo-chemical disinfection and these generally work well. Suppliers have different techniques for avoiding the mutations that occur resulting in species that are immune to such treatment.
The Robert Koch Institute in Germany has now approved many processes at both 40C and 60C which meet the strict standards demanded by national health authorities and these are widely available.
Many national health authorities define disinfection in their own terms - for example as a "log 5 reduction" in certain viable micro-organisms. So if the fabric has a concentration of 108 staphylococcus on the surface before washing then afterwards the concentration must be no more than 103.
While this appears to leave a large number of micro-organisms on the textile, producing sterile fabric with a zero count would require steam autoclaving at over 120C for each washed item. Rental operators supplying food industry workwear are consistently ahead, as most plants have internal and external controls for residual microbiological contamination.
These fall into three main groups and all are now used regularly for workwear, for healthcare linens and increasingly for hospitality work.
In-house methods using dip-slides
External contracts with microbiologists that use pre-infected swatches
External assessments using sterile swabbing.
Dip-slides are plastic plates enclosed in transparent plastic. A different growth medium on each side gives two readings of the degree of disinfection for under €5.00. In-house staff can use them with around one hour training. They act as an early warning but do not identify the precise bug and the concentration is not precise.
Pre-infected swatches are impregnated with known quantities of specific species that are safe to go into the wash process. These safe species act as "markers" for known pathogens such as MRSA and C. diff. The test swatch and an untreated swatch are put through the chosen process and are examined in a microbiological laboratory to determine the concentration of viable colonies of the marker bug on each swatch. Several types of pre-infected swatches are usually run together and the cost is usually a few hundred Euro.
Sterile swabbing involves wiping the swab on the target fabric or the target part of the machine, such as the membrane press. The swab comes in its own re-sealable sterile container. The contaminated swab is analysed in the laboratory for the type and quantity of the bugs it now carries. Costs vary with the number of species to be assessed but typically are a few hundred Euro.

EN14065 bio-contamination control
This British and European standard was published in 2002. In many ways it supersedes the guidance of the International Scientific Committee on Laundering (ISTCL), which is built into national health authority guidelines such as HSG (95) 18 from the UK Department of Health and the UK NHS.
The big difference between the ISTCL guidelines and EN14065 is that ISTCL calls for implied thermal disinfection of cotton textiles based on a wash stage held at 71C for 3 minutes plus mixing time, whereas EN14065 allows a variety of disinfection methods but requires the launderer to check that the chosen method delivers the necessary bug-kill level.
The entire risk assessment and control procedure is based on sound RABC principles, with systematic monitoring, recording, identification of staff duties and training. The standard is simply written and comparatively easy to follow, with useful examples of how to comply given in the appendix.
HSG (95) 18 has now been succeeded by the UK Department of Health document CFPP 01-04. It embodies many individual requirements and gives tips on training, job descriptions and procedures to be followed in UK healthcare establishments.
However, its structure is not as easy to follow as EN14065 and the best advice for healthcare launderers is to adopt the structure EN14065 but to comply using the specific tips given in CFPP 01-04.
Implied thermal disinfection (71C for
3 minutes plus mixing time) has been the mainstay of disinfection in healthcare laundering for many years. It has proved surprisingly effective, although also energy intensive.
However it is not effective with spore-forming bacteria such as C. diff, anthrax, bacillus cereus and several others. In spore form such bacteria are protected by an impenetrable "shell" that shelters the bug from heat and chemistry. When the conditions seem favourable, the bug will come out and develop into its vegetative state and will breed rapidly if it comes into contact with an environment that provides moisture and nutrient.
The bug can be killed easily by heat or chemicals at the vegetative stage. It is only in the spore form that it poses such a threat of cross infection for the user of the laundered textile.
When most hospitals had their own laundries, spore formers would develop from spore to vegetative state in the queue for sorting and so the majority could be killed thermally with all the other bugs. Queues do not build up as readily in modern high production units so more formers survive and must be destroyed chemically. Some modern chemical anti-microbial agents can pierce the spore's "shell" to achieve a very high kill. This type of agent also has the advantage of avoiding mutations. If chemical treatments are not used, then in the summer, when bacillus cereus can cause problems, the laundry might have to increase the rinse water flow to dilute the concentration of the most resistant bugs. Hospital laundries used this method successfully for many years. Anthrax is a spore former and a very unpleasant infection with a high fatality rate but now it is only likely to be encountered in bio-terrorism.
Laundries are not equipped to deal with it. If there is any suspicion that anthrax-infected linen is on the way to the laundry, it is best to incinerate or otherwise dispose of the entire batch of such linen, following advice from the infection control officer at the local hospital.

Hospitality textiles
The world's hotels, airlines and cruise liners deal with an international market where customers and staff have different levels of exposure to micro-organisms and infections.
The textiles supplied to these end users can form ideal bug carriers for
re-distributing micro-organisms uniformly to every user.
Napkins, pillowcases and towels are especially suitable as they touch vulnerable infection points such as hands, mouths, noses and eyes. There is a strong case for saying that if a business does not have a problem there is no need to try and fix it. However, it makes common sense to ensure that a textile that is going to be in contact with a vulnerable part of the body, such as the mouth, is disinfected to a reasonably consistent level. Over half of the commercial wash processes in daily use achieve a level of disinfection that is as good as that for healthcare textiles, so it is not particularly difficult.
The spur to trigger disinfection of all work should come from the users who, instead of concentrating on the cost and encouraging low temperature washing simply to meet a price-point, should be demanding quality standards which do more to protect the user. Minimum whiteness retention levels for towels and pillowcases are a good starting point. When a textile turns grey it is often because of re-deposition of soiling from the wash liquor. This soiling is usually protein-based so it is an ideal nutrient for bugs. A smelly grey towel is often the result of bacteria breeding on the last user's un-removed perspiration and skin sebum. Infection control is now a topic, which is being addressed by all leading launderers. The result will be cleaner circulating stocks that smell sweeter and will delight the customer. They will also be increasingly free of bugs.