A microbiological culture is the multiplication of micro-organisms (bacteria, yeasts or fungi) on a culture medium. Only when they grow into colonies, they are available in sufficient quantities that make it possible to demonstrate, identify or further investigate them.
The cultivation of micro-organisms is one of the oldest techniques to demonstrate an infection. Materials for a culture are urine, sputum (mucus from the airway), feces (stool), blood and septum (pus).
Agar is commonly used as a breeding ground for the culture. This may be enriched with various other nutrients, such as blood or certain salts, which may be needed for the growth of some bacteria.
Usually, there will be a sample taken with a sterile cotton swab from the infected area, but also body fluids may be provided in a sterile container. In the microbiological laboratory, the sample is put on a culture medium. The culture medium is transferred to petri dishes. These are flat-round, shallow glass bowls. The petri dishes are then put in an incubator, so that the various types of micro-organisms can grow. This growth will be carefully monitored. Next, they are viewed under the microscope.
The culturing of the micro-organisms may take 2 to 3 days. For some micro-organisms, the slow growers, a longer period is required.