A recently discovered group of chemicals could pave the way to better plastics for surgical implants that are more compatible to the human body and less likely to become infected by disease-causing microbes. A paper published in the January issue of Microbiology describes the unusual properties of polythioesters (PTEs) and how they were discovered.
Alexander Steinbüchel and co-workers at the Institute for Microbiology in Münster, Germany, discovered polythioesters (PTEs) while working with the bacterium Ralstonia eutropha. These bacteria form PTEs when their diet is changed to contain an acid -- thiodipropionate (TDP).
Professor Steinbüchel said, "This is the first report of a bacterial polymer containing sulfur in the backbone. The bacteria produce PTEs using enzymes called synthases. These enzymes can produce a wide variety of polymers, depending what you feed the bacteria on. The possibilities are endless."
Although implants do not provoke rejection from the human body in the same way as an organ transplant, they are not always readily accepted. The body reacts to an implant as a foreign object and sets up a mild inflammatory response, causing the patient to feel unwell. Such a reaction may also limit the implant's function or lifespan.
Implant expert Dr. Roger Bayston said, "A failed implant can mean loss of mobility, brain damage, interruption of vital anticancer treatment and sometimes death in the case of heart valves. In addition, the community costs in terms of rehabilitation, earnings and need for support are considerable."
The prospect of plastics that are more compatible with the human body could lead to longer lasting implants and speed up wound healing. In common with all new medicines, these plastics will require rigorous testing before they can be used to make surgical implants.
Surgical implants such as catheters are now used routinely in hospitals. Prosthetic heart valves and shunts to remove fluid from the brain are also quite common.
One of the biggest problems with the plastics used in these devices is that bacteria find it easy to grow on them. The infection rate for children with shunts is between 15-20%, and this can lead to brain damage. These infections are often difficult to treat and may be caused by antibiotic resistant bugs such as the superbug MRSA.
UK biopolymer expert Professor Ian Sutherland of Edinburgh University said, "This is an exciting breakthrough, the ability to produce these unusual polymers containing sulfur means that we might soon have surgical implants that are able to prevent bacteria from growing and causing infection."
Microbiology is a peer-reviewed journal produced by the Society for General Microbiology (SGM).
SGM is an international learned society with over 5,000 members worldwide. The Society provides a common meeting ground for scientists working in research and in fields with applications in microbiology including medicine, veterinary medicine, pharmaceuticals, numerous industries, agriculture, food, the environment and education.
SGM is committed to representing the science and profession of microbiology to government, the media and the general public; supporting microbiology education at all levels; and encouraging the uptake of careers in microbiology.
(Reference: Microbiology volume 147, p11-19.)
Related website:
Society for General Microbiology
[Contact: Prof. I.W. Sutherland, Prof. Alexander Steinbüchel, Dr. Roger Bayston]
22-Jan-2001
