A throat culture test is conducted to detect fungal or bacterial infection in the throat. For this test, a sample of throat swab is collected and put in a cup with special substances (culture), which helps the growth of infectious organisms. If bacteria or fungi grow the throat culture test is positive and if there is no infectious growth the test is negative. The bacteria is detected using chemical tests and/or by observing under the microscope. If indeed one finds infection in the culture, sensitivity tests are conducted to determine the most effective antibiotic treatment for the infection.
Throat cultures are done usually when you have sore throat. A throat culture test will determine whether the sore throat is the result of viral infection or bacterial infection. Identifying the type of organism is the biggest key to working out a treatment.
A throat culture is also done to identify carriers. A carrier is a person who does not show symptoms of an infection but carries the fungi or bacteria and can spread the infection in the community.
A throat culture requires absolutely no preparations. The only thing you need to do is keep you doctor informed about any antibiotics you may have taken in the recent past. Also, it's best not to use a mouthwash before the test.
For the test, you will have to tilt you head and open you mouth as wide as you can. The lab technician will then press your tongue with a tongue depressor (a flat thin stick) and then examine the mouth as well as the throat. This is to check if there are any visibly sore or red areas in the tongue. Then a clean swab is used to rub against the back of the throat, over any visibly inflamed or sore areas and around the tonsils.
Another method of collecting a sample is a throat washout. In this case, you will be asked to gargle with salt water and then spit it out into a clean sterilized cup. This method provides the lab with a larger sample which could make the culture more accurate. If this test needs to be administered on toddlers and infants, it is best if the parent holds the child in the lap as this will restrict their movements to a large extent.
As it is, when your throat swab is being collected you feel like gagging, which is a reflex reaction you feel because something is touching the back of your throat. If you have a very sore throat, then the swab collection could cause a little pain, but more often than not the procedure is more uncomfortable than painful.
The results of a throat culture test are usually available in a day or two but the time taken depends on the type of bacteria the culture was tested for. If the throat culture is conducted to determine fungal infection, the results could take as long as a week. However, if the throat swab is taken for a rapid strep test (used only to detect infection caused by strep bacteria) then the results are ready as quickly as ten minutes.
As with all culture tests, a normal result means the culture test was negative and that there was no presence or growth of fungal, bacterial or viral infection in the sample. A positive result therefore is an abnormal result indicating that the sample collected did show growth of infectious organisms. These infections include strep throat (strep bacteria), whooping cough (bordetella pertussis), diphtheria (corynebacterium diphtheriae, as well as fungal infections like thrush (Candida albicans fungus).
In case of a positive test result, further tests (sensitivity tests) are conducted to determine appropriate antibiotic treatment. Sometimes, a negative test could also mean that the sample was collected incorrectly or was contaminated thereby preventing the growth of bacteria or fungus. If the doctor suspects a false negative then you will have to repeat the test once more.