Fighting bugs and Superbugs

Jet travel has become the norm. Cheap air fares mean that large numbers of people travel the globe daily, taking with them a wide variety of bugs and viruses.

UK hospitals, nursing homes and hospices have to contend daily with superbugs which resist normal cleaning methods. The superbug MRSA (methicillin resistant staphylococcus aureous) leads to many fatalities among elderly and weak or terminally ill patients.

Hospital acquired diseases (nosocomial infections) are believed to account for several thousand deaths each year in the UK, but there has been little attempt to break the cross-infection chain and ensure that everything leaving the laundry is totally bug free.

Reassure the customer

Laundry engineers need to look at the options so they can give realistic assurance to customers concerned about the increased risks to those responsible for preventing infection from travelling across the hospital site, through the hotel or around the world with the airline.

The term micro-organisms covers a wide range of creatures from single cell viruses and bacteria to fungi to dustmites and similar creatures, which, despite being virtually invisible, still contain many millions of cells. As far as the laundry engineer is concerned, they are all best dead.

This is achieved more easily by laundering than by drycleaning. Although studies by the UK Department of Health have indicated that modern drycleaning fluid (perc) ensures the death of most micro-organisms in a standard drycleaning machine process. Bacteria and fungal growths can and do occur in a drycleaning machine. It is these which cause odours and lead to murky algae in water separators and foul-smelling bacterial excrement on the back plate of the drycleaning machine drum.

Horse slobber and fish slime are particular sources of nutrient for bacteria in drycleaning, so, where possible, washing is a far better method of cleaning horse blankets and fishermen's gear.

A few years ago adverts for domestic bleach claimed it killed 99% of all known germs, until a few wise launderers started to query with Domestos and others which germs survived!

The laboratory boffins found great difficulty in identifying micro-organisms that survive in sodium hypochlorite bleach, following which many advertisers changed their claim to include the death of all known germs.

Why then is chemical disinfection not widely welcomed across the rental and hospital sectors and for hotel use.

The answer lies with superbugs, such as MRSA. This is one of a group of bugs which has mutated. It has developed a resistant strain that now defies effective and permanent disinfection. There is no doubt that hospital infection control committees are seriously concerned not to encourage mutation and for this reason the UK's Department of Health only allows implied thermal disinfection as the main means of achieving bug kill.

Change could be on the way, as a recent article in LCN demonstrated. There are now fabric finishes with bactericidal properties that do not rely on chemistry. In these finishes the shape of the molecule pricks the cell wall causing it to rupture, so ensuring the micro-organisms' demise.

It is reliably claimed that such techniques do not encourage mutation because there is no zone of inhibition in which superbugs can survive and develop in the best traditions of Charles Darwin.

However, such techniques are unlikely to be widely used at present. Rental sheets for UK hotels are almost all based on pure cotton as are the towels and pillowcases. The same is true of hospital flatwork and there seems no prospect at the moment of raising the cost of these items by incorporating a bactericidal finish universally.

The best that can be hoped for is that this type of fabric will be adopted for operating theatre wear and for other critical fabrics where cross contamination is a real issue.

Bus for a bug

The hospital launderer and the rental operator have a duty of care to the ultimate client to provide linen which is infection free and unlikely contribute to cross contamination by becoming "a bus for a bug". The wash process must fulfil two critical demands.

First, the process must guarantee the death of every micro-organism present at the start of the wash. This is achieved by maintaining the main wash liquor at a minimum of 71C for 3minutes plus mixing time. In practice most laundries specify 75C to give a suitable margin and allow 4minutes for mixing after temperature is reached. For washer-extractors the main wash stage must run for 7minutes at 75C for cotton goods.

For polyester and polycotton goods the stage should last for 14 minutes at 65C. In a continuous batch washer the appropriate number of compartments is needed to give the desired residence time.

Secondly, the wash process must remove nutrients for bacterial growth. Blood and urine contain so much protein that if either is left on sheets or towels it makes a delightful feast for passing bacteria which will rapidly colonise it.

After a few hours in a hotel linen room, the entire sheet will be re-infected. The only mystery will be which bug you happen to be breeding and whether the hotel guest has adequate resistance to it.

So shrewd launderers are checking not only the disinfection performance of the wash processes but also the degree of soil and stain removal, concentrating particularly on protein stain removal, which is the major staining present on pillowcases, bed sheets, towels and table linen.

Bleaching theory

In theory, bleaching with 120 parts per million with sodium hypochlorite in the rinse (which is equivalent to a dosage of around 7ml of bleach as delivered per kilogram of dry work) should kill all micro-organisms.

At this level, bleach damage to the sheeting, provided the temperature is below 50C, should still permit 200 cycles to failure as far as tearing or fraying is concerned. This is equivalent to a life of two to four years in most rental or hospital applications. This level of bleaching ought to give an increase in cuprammonium fluidity of no more than 3.0rp over 25 washes, which is the conventional check.

  However, chemical disinfection using bleach is difficult to control and assure, so implied thermal disinfection is still the only technique universally accepted.

The temperature of an ironer bed is 172C and not many bugs will survive even a few seconds at this temperature. But, unfortunately the damp hem does not reach this temperature and the moisture here is not hot enough for long enough to assure a bug kill.

The same applies to multiple thicknesses in workwear passing through a tunnel finisher at 165C. The temperature is measured in the circulating air stream, not in the multiple seam.

As a consequence, bugs in the laundry water supply can and do survive and breed. This can be at its worst when a bug which enjoys eating the finish on the workwear fabric appears. This type of bug survives tunnel finishing in small numbers and then slowly breeds over the next few days, causing foul odours and other problems in the wearer's locker.

Implied thermal disinfection effectively kills most most micro-organisms. It is the standard technique for removing AIDS, MRSA, mumps and measles, yellow fever and so on. Even smallpox and dustmites cease to be major problems after a few minutes at 75C in a hot wash.

The bugs that survive are the small number of spore formers. Anthrax is an example and is a particularly nasty infection because it is frequently fatal. The spore forms a protective layer so that a good number will survive a hot wash. Hospital or hotel linen that becomes contaminated with Anthrax needs to be burnt rather than allowed to contaminate the pool of circulating stock.

CJD is still a problem, not so much in the UK but certainly in other parts of the world. It is usually transmitted by eating meat from contaminated cattle where the problem takes the form of a prion or mutated cell. However, the chances of cross infection by the laundry are very low. They are eliminated by normal good washing practice that effectively removes proteins, with a low temperature pre-wash running for at least 4minutes followed by a high temperature main wash with good detergency and plenty of mechanical action.

The standard technique for checking the effectiveness of disinfection in washing is to swab the textile surface immediately at the end of the wash process and then transfer any bugs onto a nutrient medium and watch the colonies grow and multiply.

Once they become several million strong you can see bright green or bright scarlet clusters with the naked eye.

The laundry dipslide has simplified this process. This is a white plastic slide coated with an amber coloured gel containing every nutrient necessary for healthy bug growth. The slide comes in a clear Perspex sterile tube. It is taken out and quickly dabbed onto the surface of the cheese as the membrane press head rises at the end of the tunnel washer.

Don't breathe on the slide

Alternatively the engineer can lean into a washer-extractor at the end of the last rinse and dab the surface of the freshly washed linen exposed there. It is important to avoid breathing on the slide or rubbing it against the skin because that will transfer other bacteria which have nothing to do with the wash process being monitored.

If the wash stage disinfection has worked perfectly, the slide should be totally clear of colonies after a few days and the process can be given a clean bill or health.

Conversely, if any bacteria do survive, these will multiply to form a wide variety of red, black or green furry colonies which are visible to the naked eye and quite alarming to the viewer.

Once the slide has given its information it should be sterilised by incineration or by immersion in neat bleach overnight, before being discarded.

You do not need a degree in bacteriology to break the cross-infection cycle, eliminate nosocomial infection and assure every customer that every piece of work you send back to them is hygienically clean. This attention to detail separates the professional operator from the cowboys.