Transmissible spongiform encephalopathies are a group of fatal,
neurodegenerative diseases commonly known as
prion diseases.
Prion diseases can resist traditional inactivation strategies and may be iatrogenically transmitted by
surgical instruments through the human population. These properties have led to the need for a suitable detection method of the
prion infectious agent, and increased pressure regarding the development of anti-
prion cleaning methodologies that would ensure the safety of
surgical instruments. Although other techniques have been applied, the animal bioassay remains the 'gold standard' method for assessing infectivity. As the vast majority of
surgical instruments are made of
stainless steel, and in order to test this surface using the animal bioassay, the application of very thin surgical
stainless steel wires has been widely adopted. These wires are easily inoculated and may be reimplanted into animals without the requirement for elution of the residual material. However, their comparability to the dimensions, shape and size of
surgical instruments is questionable. This article shows how such contaminated wires (residual
protein between 6.3 and 16.0 ng/mm(2)) can be cleaned more easily than flat
metal surfaces (residual
protein between 63.9 and 89.3 ng/mm(2)) under comparable conditions using recommended cleaning agents. These results indicate that the application of wires as a realistic means of assessing the removal or inactivation of the
prion infectious agent from
surgical instruments should be treated with caution.