Biofilms and Medical Devices: “A Race to the Surface”

A literature review was conducted to examine the determining factors and relationships for the formation of bacterial biofilms to foreign body implants (implantable or indwelling medical devices). With the increased use of biomaterial implants and short term use devices, biofilm formation by certain bacteria can lead to a decrease in effectiveness of medical devices leading to persistent and relapsing infections. Once a biofilm has formed, the bacteria comprising these biofilms are protected from killing by antibiotics and the body’s immune system. The prognosis for the patient is usually poor resulting in the removal of the implanted or indwelling medical device.

Following the implantation or introduction of a biomaterial, the host produces a foreign body response. A biomaterial-blood interface is immediately created with the first step being a non-specific adsorption of blood and tissue fluid proteins on the whole surface of the foreign material. The second step is the intervention by immune and inflammatory cells attempting to protect the host by walling off the foreign biomaterial in a fibrous capsule.

During the acute response by the host, a competition is underway by both bacteria attempting to colonize the biomaterial surface and the host’s immune system. Gristina has coined this foreign body reaction as “A Race to the Surface”. That is, the successful integration of the biomaterial into a host largely depends on the outcome of this competition between the immediate immune response by the patient and the rate of bacterial attachment and accumulation.

It is the aim of this paper to provide a review of current biomaterial development and modifications designed to minimize the probability of bacterial attachment, colonization and biofilm formation by Staphylococcal epidermidis. A brief overview of the virulence factors of Staphylococcal epidermidis will be presented followed by specific interventions in development or being employed to interfere with bacterial adhesion, aggregation, bacterial growth, disaggregation and bacterial communication on biomedical devices.