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Module 2, Microbiology:

Microbiology (Basic terms for the quality-management and hygienemanagement resp. for the conversion of EN 14065)

In this Module the possibility of learning the basics of microbiology is given. It also contains hygiene-relevant special knowledge for the laundry area and textile-service enterprises respectively in order to guarantee an appropriate conversion EN 14065 (RABC-system) with regard to microbiology. While you find a detailed overview dealing with microbiology in the power-point presentation, in this present chapter important items are explained in order to guarantee a better understanding of the background of microbiology.

The beginning of microbiology can be dated with the discovery of microorganisms by Robert Hooke and Antoni van Leeuwenhoek (about 1665-1670).

Microbiology is a part of biology and deals with microorganisms and viruses. Microorganisms are creatures which, as a rule, are so small that they cannot be recognized with the naked eye like Monads, organisms with few cells, bacteria, protists and fungi. Big amounts of agglomerated individuals might be seen also with naked eyes (for example: bakers yeast or even colonies of bacteria). For hygienically proper textiles primarily bacteria and fungi are of great importance. By the way, the item “fungi” does not refer to the eatable mushrooms, which, because of their size, do not belong to the category microorganisms but those that, because of their size, represent an almost invisible danger, such as Aspergillus flavus, which is counted among one of the most dangerous moulds because of its toxin-production.

While fungi belong to the eucaryots and show a nucleus, bacteria are procaryots and consequently show no nucleus. The characteristic attribute is the cell wall, which can be missing in a few cases (for example mycoplasms). The cell wall constructs the characteristic shape of the bacterium (e.g. coccus, rods, helical and convoluted bacteria), protects against environmental effects and makes the bacterium able to be coloured.

Most of the medical relevant bacteria are able to be coloured with the standardcolouring recording to Gram. The result is differentiated between gram-negative bacteria (red-coloured, for example Escherichia coli or meningococci, those bacteria have a thin cell wall with an external membrane) and gram-positive bacteria (blueviolet coloured, for example Staphylococcus aureus, those bacteria are identified by a huge cell wall, which misses the external membrane).

Some kinds of bacteria are not or only badly able to be coloured as for example mycobacteria. For the proof of their existence a special method is applied.

The ability of being coloured and the shape of bacteria point out to first clues in the diagram of characters which are examined within the routine-diagnosis by infectionviruses.

Recommendation for interested:

  • Madigan, Michael T.; Martinko, John M.; Parker, Jack: Brock - Microbiology. Spektrum Akademischer Verlag. 2000. ISBN 3-8274-0566-1 (current issue)

In this module no medical overview on viruses etc. is given; solely the problem “germs in the laundry” and “germs on textiles” shall be entered. It has to be taken into account, that there exist microorganisms (bacteria as well) which represent a health (hygienic) risk (so-called human-pathogenic germs) for the human as well as such by no means of hazard (for example bacteria-cultures in yoghurts or blue-veinedcheese). For this reason besides a bioburden determination a selective determination of germs to rate the quality or the risk is required while microbiological investigations.

Additionally it has to be differentiated for example between the dirty-laundry area and the expedition-area because in the delivered dirty laundry all those microorganisms can be found that are also found in or on humans, whereas in the delivery-area after implementation of a hygiene-management-system such as the RABC-System for the hospital- and food-area no human-pathogenic germs may be detected.

Furthermore with regard to the implementation of a hygiene-management system such as the RABC-system it has to be differentiated between the different kinds of (microbiologically) demands. Besides this in areas such as “health-area” or “foodarea” there exist several varieties in subordinate levels as different kinds of wards in the hospital or different risk-categories concerning working-clothes in the food area.

In general the clean laundry has to be free of pathogenic-germs and has to be sterile for certain purposes (for example in the hospital-area). Used laundry is microbial polluted and is also able to spread pathogenic-germs as well at the customers as in the laundry.

Furthermore mistakes on handling and transportation of clean laundry can lead to their recontamination (re-pollution with dirt and microorganisms).

For this reason in consideration of medical concerns a more frequent change of workwear according to the risk-area is necessary. Doing so, different risk-areas have to be taken into account: cf. common wards with transplantation-unit, raw materialacceptance with production in the food-area.

After an appropriate risk-analysis (according to EN 14065 – the RABC-system) however different hazards may be taken into consideration and if applicable, countermeasures can be defined in order to estimate the risk of microbial contamination and keep it as small as possible.

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