Scientists to assess best way of cleaning surgical instruments to prevent vCJD infection risk

A new study will examine the best methods for cleaning surgical instruments to reduce the risk of variant CJD infection.

The 90,000 study, funded by the Scottish Infection Research Network, will focus on instruments used in neurosurgery and test different methods for cleansing surgical instruments.

A recent report in the BMJ found that approximately one in 2,000 people in the UK carry vCJD, the human form of ‘mad cow disease’, without displaying any symptoms – higher than previously thought. Only 177 cases of the disease – Creutzfeld Jacob Disease have been recorded in the UK.

There is no cure for vCJD and no test to screen for it in blood donations, so scientists are keen to ensure that surgical instruments used in operations do not present a risk for transmitting the disease which is caused by a prion – an infectious, misshapen protein.

Professor Andrew Smith of the University of Glasgow who is leading the study which also involve NHS Greater Glasgow and Clyde and Health Facilities Scotland, said: “With new data suggesting that one in 2,000 people potentially carrying vCJD prions, the risk of transmission of the disease via surgical instruments remains a public health concern.”

“Coupled with this, the resistance of prions to heat sterilization means the cleaning stage is important to remove any potentially infectious tissue. “

“A major factor influencing cleanability for instruments is the ability to prevent drying of residual tissue onto the instruments. There is some evidence to suggest that the longer you leave dried-on residues on instruments, the more difficult it is to remove.

This project aims to provide an evidence base for improved cleaning and risk reduction for neurosurgical instruments.”

The scientists will investigate different processes, in-vitro and in-vivo, to improve the cleaning of instrument based on existing and novel protein-detection assays.

They will consider efficacy, cost-effectiveness and ability to integrate the cleaning techniques into existing operational processes for instrument decontamination. The study will use standard and new protein visualisation techniques to improve surgical instrument quality control by measuring and locating any residual tissue left on surgical instruments.

The prions responsible for vCJD have high heat resistance and are not eliminated by the heat treatment surgical instruments usually undergo in a steam sterilizer.

Methods to inactivate prions such as concentrated bleach or sodium hydroxide are time consuming and damage delicate surgical instruments.

Prof Smith added: “Ideally we’d like our study to lead to improvements in the cleaning and sterilization process across all surgical specialties, rather than just picking out operations and patients at higher risk.”

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