The reduced effectiveness of antibiotics is not only an important issue for human health. For example, plants can have a gene inserted which enables them to secrete an antibiotic against fungi. Siemen Schoustra believes that the added value of these genetically-modified crops is smaller than thought, as the fungus soon becomes permanently resistant to the antibiotic so that the plants still become diseased. The first resistant plant fungi have already been found in India.

Evolution is the cause of the resistance. However this resistance should disappear again, as resistant fungi and bacteria grow less well in an environment without the substance they are resistant to and are therefore outstripped by their faster-growing non-resistant counterparts. Yet, some variants remain permanently resistant.

Permanent resistance occurs in two stages. The fungus first of all becomes resistant due to a change in its DNA and then a second such change ensures that the resistant type eventually grows just as quickly as the non-resistant types. The result is a sort of super fungus, which is resistant and can also grow quickly under all circumstances. This leads to the resistance becoming permanent and therefore the effectiveness of antibiotics being reduced.

Researchers are trying to hinder the development of resistance in bacteria and fungi in an attempt to prevent the antibiotics from becoming obsolete. Their efforts are primarily focussed on understanding and preventing the first stage, whereas the second stage is often omitted. Schoustra's research reveals that hindering the second stage (compensating for the negative effects of resistance) is extremely difficult, as bacteria and fungi can compensate for the negativ
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Contact: Sonja Knols
press@nwo.nl
31-70-344-0826
Netherlands Organization for Scientific Research
16-Dec-2004