It is not possible to sterilise whole blood products and therefore they must be collected aseptically. Horse and sheep blood are the most widely used animal blood products in culture media. The choice of  which type of blood to use with culture media is largely traditional, with much of continental Europe preferring sheep blood, whilst the UK and  certain parts of the Commonwealth  prefer horse blood. Defibrinated sheep cells are aseptically collected whole sheep blood that has been processed to remove fibrin. There are no additives or preservatives in this product. Defibrination is now accepted as the best method of preventing blood clotting. It must be carried out immediately after drawing the blood and the agitation must be sufficient to denature the fibrinogen but not to cause rupture of the erythrocytes and haemolysis. The haemolytic reactions of sheep blood are not identical to the reactions of horse blood and blood agar media designed for sheep blood may not be satisfactory with horse blood and vice versa.

Lysed horse blood is used for special purposes in culture media. It has been used for many years in Corynebacterium diphtheriae media, where better growth was observed after lysis of the horse blood by the tellurite in the medium. It is also documented that lysed blood stimulates the growth of Haemophilus influenzae due to the release of Nicotinamide Adenine Dinucleotide in the horse blood from the ruptured erythrocytes. In antibiotic susceptibility testing, lysed horse blood is added to the medium to improve the reactions with trimethoprim and sulphonamides. Most culture media, unless specially processed for susceptibility testing, contain amounts of thymidine which can antagonise the inhibitory effects of these antimicrobials. When horse blood is lysed the erythrocytes release an enzyme thymidine phosphorylase which converts thymidine into the much less antagonistic compound thymine.

All E&O products are for in vitro use only. E&O products are intended only for use by qualified professionals who will safely handle and dispose of products they receive. All biologically derived materials (e.g. blood, sera) should be handled as if a potential biohazard. E&O media that contain antibiotics should be handled with care. Chemical resistant gloves, eye protection and laboratory coat should be worn.

It is not possible to sterilise whole blood products and therefore they must be collected aseptically. The sodium citrate solution that is added to the sheep blood is manufactured from a salt through the reaction of sodium carbonate with citric acid and this solution serves as an anticoagulant and helps to preserve the blood. The Sheep Blood Citrate (SBC) is aseptically collected and prepared to order from our colony of animals. Sheep Blood Citrate is ideal for blood agar plate preparations. Blood Agar is a general purpose enriched medium often used to grow fastidious organisms and to differentiate bacteria based on their haemolytic properties. Citrated Sheep RBCs are also useful for the titration of Complement, adsorption procedures, testing for agglutinins/HA assays, and for other serological testing.