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Avoparcin temporarily banned as a feed additive in animal nutrition

01/1996, 29.01.1996

New data confirms suspicion of resistance development

The glycopeptide antibiotic, avoparcin, is authorised in the European Union (EU) as a performance-enhancing agent and is used in Germany in animal nutrition for poultry, pigs, cattle and calves. The Federal Ministry for Nutrition, Agriculture and Forestry has initially banned the use of avoparcin for six months on the recommendation of the Federal Institute for Health Protection of Consumers and Veterinary Medicine, BgVV. New data have confirmed the suspicion that the use of avoparcin in animal nutrition promotes the development of resistances to glycopeptide antibiotics and thus reduces treatment possibilities in human medicine. The federal government must justify this Member State measure within the EU and put it up for discussion.

Resistances to glycopeptide antibiotics are being increasingly observed in so-called enterococci. Enterococci are a natural component in the intestinal flora of humans and animals. They are potentially pathogenic, i.e. under certain circumstances they may trigger severe infections, for instance in immunosuppressed patients in intensive care wards.

Infections with enterococci can be treated with conventional antibiotics. If a pathogen is resistant to these antibiotics or if a patient reacts allergically to these active substances, glycopeptide antibiotics like vancomycin and teicoplanin are used as reserve antibiotics in human medicine. It would be far more difficult to treat these patients if pathogen resistance to these reserve antibiotics were to spread.

Resistant germs may emerge where antibiotics are used against microorganisms. This also applies to the formation of glycopeptide-resistant enterococci strains. Two main causes are under discussion: the indiscriminate use of glycopeptides in human medicine and the use of (other) glycopeptides as performance-enhancing agents in animal nutrition. In Germany only avoparcin has been given marketing authorisation as a feed additive in this active substance group.

At an international expert hearing at BgVV in Berlin on 1 and 2 June 1995, the suspicions about the use of glycopeptide antibiotics as performance enhancers in animal nutrition were discussed. In animal stocks in which these substances are used, there may be a selection of resistant enterococci. The germs may reach the human sector via the animal sheds and then spread in hospitals.

The data available in June 1995 did not refute the involvement of avoparcin in resistance development: however, the majority of experts felt they were insufficient for the enforcement of an application ban in animal nutrition. The participants agreed that further studies were necessary in order to estimate whether, and, if so, to what degree resistant enterococci occur and on what scale they can be transmitted from animals to humans.

In the meantime new studies particularly from Scandinavia confirm that the use of avoparcin promotes the selection of resistant germs. Vice versa, if no glycopeptide antibiotics are used in animal husbandry, no specific resistances to glycopeptides occur. Moreover, experimental and clinical trials indicate that the specific glycopeptide resistance can spread to other types of germs.

Although the link between a specific glycopeptide resistance now proven to have been caused by animal husbandry and the resistance occurring in hospitals is still not unequivocally proven, the suspicions about avoparcin have been so clearly confirmed that the use of glycopeptide antibiotics must be kept to an absolute minimum. Given the increase in resistance observed there have already been calls for restrictions on the use of glycopeptide antibiotics in human medicine. This demand can only be met in the field of animal husbandry in the opinion of BgVV at present by suspending marketing authorisation.

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