Cells and Materials


The biomaterials used in the manufacture of implanted prosthetic devices profoundly impair the host's ability to opsonise and phagocytose invading microbes. As a result, while these devices generally provide effective relief from painful, crippling and life-threatening disorders, they can also induce vulnerability to infection in the recipients. The surfaces of the implants are susceptible to colonisation by microbial biofilms. The cells in the biofilm.s are further protected against opsonophagocytosis and are also resistant to antibacterials. Device associated infections thus tend to be refractile to antibiotic therapy and in many cases the device has to be removed before the infection will respond to treatment. Infection rates per implantation operation in totally implanted devices, such as, artificial hips and knees, have fallen over the years to 1-2%. Devices that are partly implanted into body cavities or pass transcutaneously into tissues are particularly susceptible to infection. For example, infection rates of 2.3-4 5% have been reported for central line vascular catheters. The incidence of infection is related to the length of time the device is in place. Infection rates for urethral catheters indwelling for more than 28 days approach 100%.

While several ingenious approaches are currently being taken to modify the surfaces of biomaterials, it has not yet proved possible to reduce the deleterious effects on the host or frustrate the surface colonisation mechanisms that microbes have evolved as a basic survival strategy in natural aquatic habitats.

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