After the throat sample has been collected, the swab is put into a container and labelled. In many places, the label will be pre-printed with the patient's name and identification number.
After the sample has been labelled, it is transported to the laboratory to be logged into the laboratory's information system. The tube label contains all the information necessary to ensure that the sample is analysed for all the tests requested and the results are matched to your name. Usually, a laboratory number is given within this information and by recalling each specific number the lab is able to track where the specimen has been at all given times.
Once in the lab, a biomedical scientist will transfer the throat cells that are on the swab to a material (agar) in a petri dish that will encourage the growth of bacteria. To do this, the swab is gently rubbed or streaked over the surface of the agar.
Recently total laboratory automation has taken over this role enhancing productivity and the accuracy of the test. Currently two major systems exist: Becton Dickinson Kiestra system and the Copan WASP system.
The sealed, labelled petri dish is placed in an incubator, which is a chamber that maintains a constant temperature that is optimal for the growth of the bacteria. The culture usually remains in the incubator for 24 - 36 hours to allow sufficient time for any bacteria that may be present to grow.
After the incubation, a scientist will visually examine the culture. Some bacteria have a characteristic appearance that enables the scientist to identify the specific bacteria. In some situations, additional tests may be needed to make the identification. Not all bacteria are harmful and require treatment. Nowadays, identification of bacteria can be done in a quick and cost effective manner using mass spectrometry and laboratory automation.
Testing for treatment
If harmful bacteria have been identified in the throat culture, the laboratory will do an additional test using different types of antibiotics to see which one is most likely to stop the infection. The most common method used universally is antibiotic disc diffusion method. This test starts by coating the surface of another agar dish with the bacteria. Antibiotics that have been absorbed into white paper discs are placed on the plate. If an antibiotic stops the bacteria on the plate from growing, it appears as a clear halo around the disc. This tells the doctor which antibiotic they can prescribe to cure the throat infection.
Currently, there are enhanced robotics in microbiology, that with the aid of fluorescent substances or pH indicators are able to perform the above test in an efficient manner.
The culture results will be recorded in the laboratory’s computer system. The results may be sent to the doctor’s computer, faxed, delivered by courier or posted to the doctor's surgery.