Washing processes

Tips for microbiologically clean hospital linen

Linen in care centres are submitted to special treatments to prevent the transfer of nosocomial (or hospital acquired) infections that are becoming an increasing problem through microorganisms (staphylococcus aureus, enterococcen, Clostridium difficil, Acinetobacter, Bacillus cereus, Pseudomonas aeruginosa, Candida sp.) both in hospitals as in crèches and elderly and nursery homes. Disinfecting the “dirty” linen from these care centres is therefore an important element in the battle against these infections. After having been submitted to cleaning, the linen has to comply with both physical-chemical and microbiological criteria.

In view of these infection issue, the High Council for Hygiene (Belgian FPS Public Health, Food Chain Safety and Environment) published its “Recommendations regarding the treatment of linen in care centres” in 2005. The directives of this document are legally binding to care centres.

The recommendations apply to all care centres admitting patients, elderly, young children or disabled people, and are therefore not restricted to hospitals. In other words, all institutes for middle or long term admissions are concerned: revalidation centres, elderly homes and crèches.

Moreover, the directives apply to all textiles used in these institutes: flat linen, linen used in operating theatres, workwear, delicate linen, clothing for residents, textiles used for cleaning, curtains, textiles for folding screens, bedding (mattresses, pillows, sheets and blankets) may all be carriers of nosocomial germs.

It is therefore obligatory to assess the disinfecting properties of all textile cleaning programmes by means of a microbiological analysis.

Test procedure

During the microbiological analysis of the laundering process, the linen is artificially contaminated with representative target organisms (usually staphylococcus aureus (Gram+) and escherichia coli (Gram-)) and then submitted to a routine washing cycle. The linen is examined during the washing cycle (count of number of surviving target organisms) to determine its disinfecting efficiency. At the same time, the last rinsing water is also submitted to a bacteriological analysis (count of organisms).

The test is passed when the number of target organisms during the washing cycle has been reduced by at least a factor 104. Moreover, the rinsing water may contain maximum 10 organisms other than the target organisms per square centimetre and/or 100 organisms/ml rinsing water.

Centexbel performs these microbiological inspections in laundries and evaluates the disinfection efficiency of their washing processes. We issue a certificate of compliance with the recommendations of the High Council for Hygiene.

Centexbel helps to identify and solve problems when the test results do not respond with the requirements of the High Council for Hygiene or with the own specifications of the care centre.

Tips for an optimum service

During the washing process, the linen is disinfected through a thermal treatment generally combined with a chemical one. The disinfection can only be obtained by combining several parameters, three of them being crucial ones:

  • type of treatment (temperature and concentration of chemical product)
  • duration of the treatment
  • type of washing cycle (depending on the type of washing machine)

A treatment at a certain temperature and with a certain concentration of chemical products in a washing machine with tumbler does not guarantee the same result in a laundry tunnel.

A second important element in obtaining microbiologically clean linen is the microbiological quality of the water. Therefore, it is necessary to use microbiologically clean water during all rinsing phases following the washing phase, that is the general disinfecting phase. The rinsing phases are usually performed at lower temperatures and sometimes without adding a disinfecting agent or chemical product. Hence, the use of microbiologically unclean water may contaminate the linen again.

Moreover, one has to keep in mind that still water is a breeding place for microorganisms, especially when it contains soap residues. Certain germs tend to form a bio-film that are extremely difficult to remove without a mechanical intervention. They also adhere to very inaccessible places such as pipes and at the bottom of wash tubs. In this way the machine and the linen are contaminated over and over again after the disinfection phase. This is the case in laundry tunnels.

The ideal - however utopian - situation is that the washing machine is completely emptied when not in service. The possibility to remove still water as much as possible must be a decisive criterion in selecting and installing a linen laundering process in care centres.

Disinfecting linen is indeed not a simple process and drafting a very specific internal set of procedures is therefore crucial. The standard RABC (EN 14065) meets this need.

After the cleaning cycle one also has to prevent that the linen is contaminated during the finishing and packing phase, even if the clean zone is physically separated from the dirty zone. The working conditions – in terms of air purity and cleanliness of working surfaces in contact with the linen – and the staff’s hygiene are also important elements in preventing the recontamination of linen after washing.

Centexbel often takes test samples to assess the microbiological state of linen ready for delivery and verifies whether it complies with the recommendations of the High Council for Hygiene.