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Helpers with a catch - Besides their positive characteristics, enterococci also have negative ones

14/2002, 05.06.2002

Experts from various countries discuss their use in foods

"Enterococcal strains which are used as probiotics or in food production must be clearly characterised and safe". This is the conclusion of participants in the international symposium "Enterococci in Foods- Functional and Safety Aspects" which was held at the Federal Institute for Health Protection of Consumers and Veterinary Medicine, BgVV, from 30 to 31 May 2002.

Enterococci are classified as lactic acid bacteria and occur in many variations in the environment, in animals, in man and in traditional foods like cheese or raw sausage. Unintentional contaminations with enterococci are seen as an indication of poor hygiene conditions during production and processing. At the same time, enterococci play an important role in fermentation and maturation processes and contribute to the special and intended flavour of foods like buffalo mozzarella, Camembert, goat's cheese and various types of Greek cheese. In the research project "Enterococci in Food Fermentation: Functional and Safety Aspects" of the European Commission, the functional, health and safety aspects of enterococci were examined with regard to foods and probiotics (probiotics are bacteria which trigger positive health effects when they reach the intestines in sufficient quantities). The results of this study were presented and discussed at the symposium.

Around 25 different enterococcal species have been identified up to now. The most important are E. faecium and E. faecialis. As components of healthy human intestinal flora, they both play an important role in the digestive system of man and animals. Enterococci, especially E. faecium strains, therefore, assume a special position in the new class of probiotic foods. Studies show that strains used as probiotics may have a positive effect on the microflora of the digestive system. Defined enterococcal strains are, therefore, also used in human medicine for therapeutic purposes.

Enterococcal strains are also used in veterinary medicine and animal nutrition. It has been demonstrated that they can help to reduce the use of antibiotics.

On the other hand, it is also known that certain enterococcal strains (in particular certain E. faecialis strains) can trigger infections in humans whose immune system has been considerably impaired. The number of infections in which enterococcal strains of this kind are involved is on the increase. Up to now, they have only been observed in hospitals. A connection between these "nosocomial" (typical for hospital) infections and the consumption of foods or probiotics has not been proven up to now and is thought to be unlikely.

One special problem should be mentioned. An increasing number of enterococcal strains has been found in animals and man which are resistant to major therapeutic antibiotics (e.g. penicillins, aminoglycosides, glycopeptides like vancomycin and teicoplanin and streptogramins). Furthermore, resistance to vancomycin and teicoplanin can be transmitted to enterococcal strains which had not been resistant up to now. There are fears that antibiotic resistance can be transmitted to other bacteria strains, too. Multi-resistant enterococcal strains are, therefore, considered to be a serious risk. When selecting probiotic enterococcal strains and strains to be used in food production as starter cultures or for fermentation purposes, the experts are of the opinion that special attention should be paid to this aspect.

The question has still to be clarified as to the extent to which the occurrence of antiobiotic-resistant enterococcal strains in man is triggered solely by the use of antibiotics in human medicine or also by resistances in animals and, more particularly, animals which are used for food production.

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