A composite block is a replacement for routine control tissue.
Research type
Research Study
Full title
The use of a composite control block for infectious organism tinctorial stains is a viable replacement for conventional control block material.
IRAS ID
226774
Contact name
Chantell Hodgson
Contact email
Sponsor organisation
Ulster University
Duration of Study in the UK
0 years, 3 months, 19 days
Research summary
The quality and accuracy of every laboratory investigation that takes place is required to be assessed. In cellular pathology this quality control is achieved through the running of known positive tissues through the investigation alongside the patient’s sample. For the majority of histological investigations, the positive control tissue is only required to contain a tissue structure, for example fibrin or collagen. For the more complex investigations, such as the detection of microorganisms, the control material is required to contain the bacteria responsible for the infection. An example of this would be tuberculosis, which is caused by Mycobacterium tuberculosis.
The great improvements in point of care testing and early detection of these infections, alongside the implementation of legislation governing when and where human tissue samples can be used for controls, has led to a shortage in infection positive material. Laboratory staff members often face lengthy and often impossible searches of archival material to locate this material. The alternative is purchase material from a commercial source, the cost of which is often high, and with the need to make savings, an alternative supply is needed.
This study with use microbiology techniques to culture named bacteria which will then be made inactive using formaldehyde fixation. The now inert bacteria will then be fixed in a thrombin clot before being processed alongside routine histological material. The clot will then be embedded alongside non-pathological important tissue to produce a composite block. Using this, slides will be subjected to the relevant laboratory investigations.
The expectation is for the bacteria in the clot to be demonstrated with the primary stain of the identification techniques, whilst the non-pathological tissue will be used to control the quality of the secondary stains. The sections produced should be able to achieve high scores when submitted for external quality assurance assessment.
REC name
London - Camden & Kings Cross Research Ethics Committee
REC reference
17/LO/1294
Date of REC Opinion
4 Aug 2017
REC opinion
Further Information Favourable Opinion