The current importance of CoNS infections is emphasised by the frequency with which these organisms are isolated from the blood of hospital patients. This figure rose to more than 3000 in 1993. Among the many recent advances in medicine, the ability to deal with degenerative or traumatic joint disease, vascular heart disease, malignant conditions and kidney failure, has been aided by the use of biomedical material implants. Furthermore, the ability to monitor and treat patients with acute medical conditions effectively has been assisted by the availability of pressure monitoring systems, arterial grafts and intravenous catheter devices.
Infection can arise for a variety of reasons.
With intravascular devices, for example, there is direct contact between the blood and the external skin flora. Other prosthetic devices which are inserted deep within the body, such as heart valves or joints, run the risk of becoming infected during the operation. Clinical recognition of such infection can be delayed for weeks or months after surgery, owing to the indolent nature of many CoNS infections. The results can be particularly devastating with prosthetic joints, as these are often inserted into the elderly, who are less able to cope with the further major surgery that is usually needed to eradicate persistent infection. Similarly, infection of a prosthetic heart valve presents a major clinical dilemma.