Surgical instruments or implants that are contaminated with residual bacteria, or pyrogens, can cause blood poisoning in patients. Researchers are developing a test that imitates the human immune system in the laboratory, eliminating the need for animal experiments.
Endoscopes and catheters are often recycled after use in a surgical operation. Various tests ensure that the devices do not jeopardize patients' health. They must be sterile, i.e. free of living bacteria, and must not have any pyrogens attached to them. These are fever-inducing residues of fungi or bacteria which can cause blood poisoning if they enter a patient's bloodstream.
There are currently three different methods of detecting pyrogens. One is animal testing on rabbits, which is controversial and also expensive. Another involves tests on whole human blood: If pyrogens are added, the immune cells secrete fever-inducing substances that can be detected in the laboratory. The problem with this test is that it requires a healthy blood donor and as fresh a blood sample as possible. A third possibility of tracing pyrogens is to use an extract from a horseshoe crab, which congeals as soon as fever-inducing substances are added. However, this test can only recognize one of the existing types of pyrogen.