Imitation (hygiene)
The contact (also contact test or contact sample ) is a technique for determining the level of contamination of objects and people in the food-producing industry and the pharmaceutical industry within the framework of "good manufacturing practice ". During the contact process , plastic containers with sterile ready- to-use culture media are pressed against objects or parts of the body of people in order to transfer the microorganisms (for example fungi and / or bacteria ) located there. The container is then closed and incubated in an incubator . After the germs have grown, the biological contamination can be determined by a qualitative determination of the species and a quantitative counting of the colonies.
Contact plates
Contact plates are usually flat plastic dishes that are filled with a sterile nutrient medium (e.g. entero agar , malt extract agar). There is usually a grid on the underside of the bowl, which makes the final count easier. On the side surfaces of the bowl, the culture medium bulges upwards to make it easier to set off.
execution
With the contact, the nutrient medium is pressed onto the surface to be tested. The closed bowl is placed in the incubator, where the adhering microorganisms quickly multiply into countable “colonies” that can be seen with the naked eye. Which and how many microorganisms can develop on a plate depends on the composition of the culture medium. Another criterion is the tested surface and the food that may be produced.
Expressiveness
The results of a contact test are primarily used for orientation. Taking into account the nutrient medium as well as the incubation temperature and duration, a statement is made about the quantitative occurrence of microorganisms and their reproduction under atmospheric oxygen. According to the appearance of the colonies, cotton wool-like molds can still be distinguished from yeasts and bacteria . A further differentiation, however, is not possible or only possible with the use of other methods.
Applications
In the following application examples are given in which contact tests are usually carried out routinely.
- Hygiene check of clean rooms
- Building renovation
- Wound management
- Hygiene examinations of furniture or clothing
- Local contamination of humans and animals
- Hygiene check of humidifiers in ventilation systems according to VDI 6022
Individual evidence
- ↑ Ulrich Thomé: Neurosurgical and neurological care: special care and intensive care . 2nd Edition. Springer, Heidelberg 2003, ISBN 3-540-43281-7 , pp. 325 ( limited preview in Google Book Search).