Search

When bacteria grow in close association with solid surface, they constitute a microbial community tight included in the exopolymer glycocalyx. Many laboratory studies have shown that these bacteria are 10 to 100 folds more resistant to disinfectants than the bacteria of the same strain in suspension. Several factors are responsible for this resistance: the glycocalyx which limits the diffusion and reacts with the disinfectant, the more or less dense repartition of the bacteria inside the biofilm, their physiologic state with reduced metabolism, and the surface on which is the biofilm. The activity assessment of disinfectant agents is achieved with standardized methods. They must take into account not only the conditions in which the disinfectants are employed, but also the micro-organism state. Experimental results showing the resistance of biofilm bacteria must lead to elaborate methods allowing the assessment of bactericide activity of disinfectants against biofilm bacteria.

The coming to light of new concepts in environmental microbiology, particularly the notions of bacterial adhesion and of biofilm or of cells in starvation, conducted to an evolution of the standardization of the controlled contamination area. It is necessary to match to the biocontamination of hazard area the principles governing the quality insurance used in alimentary industry named HACCP (hazard analysis of control critical point). This method will have to be applied wilfully to all the fields where a patient or a product risk a biocontamination.

Working with pathogens or genetically engineered micro-organisms is a potential hazard for scientists, health care workers, employees of pharmaceutical industry, and also for the environment. Carelessness, poor technique in the handling of infectious materials, needle sting or infectious aerosol exposure are the cause of laboratory acquired infection. Biosafety, corollary of biocontamination, is based on the combination of good microbiological techniques, facility design of the laboratory and safety equipment. So, four biosafety levels are appropriate for the operations performed and the hazard posed by the infectious agents.