4.4 Procedures for bacterial isolation

The process of bacterial isolation starts with the arrival of the specimen and concludes with obtaining the ‘clinical isolate’: a pure culture or suspension of the bacterium presumed to be the cause of the infection.

Most laboratories, including animal health laboratories, offer culture routines which target clinically or economically important organisms relevant for the region. Animal health laboratories will generally only look for and identify bacteria relevant for the animal from which the sample has been taken and endemic for the particular country.

Laboratories establish their own routine culture procedures based on various considerations, including the:

• pathogens common in the region
• number and types of specimens received
• availability of technical personnel, supply and equipment
• cost-effectiveness of culture compared with other tests.

Cultures for uncommon organisms, or organisms with complex nutritional requirements (for example, strict anaerobes, rickettsial pathogens, mycobacteria, mycoplasmas) are often not offered (non-culture-based methods may be offered instead), or are only offered by reference or specialist laboratories.