In Medicine, what is a Culture?
In medicine, a culture is a test which is performed to look for organisms which could be causing disease in a patient. To perform a culture, a sample is taken from the patient and placed into a petri dish with growth medium, allowing any organisms present to multiply and flourish. After a set period of time, the dish is examined under the microscope to identify any organisms which may be present. In some cases, cultures are designed for specific organisms, in which case the culture medium may be designed to encourage the growth of something in particular.
A variety of biological samples can be cultured to look for infections, including urine, blood, skin scrapings, and tissue samples. A culture is generally ordered when a doctor suspects that a medical condition may be caused by an infectious agent, and he or she wants to identify the agent to decide on the best course of treatment. Understanding the cause of a condition before offering treatment is important, as otherwise the wrong approach or medication could be used.
In a classic example of a culture, a patient might present to a doctor with complaints about difficulty urinating. The doctor might suspect that the problem is caused by an inflammation in the urinary tract, in which case he or she would request a urine sample and order a urine culture. After culture, the urine might reveal a bacterium which has the potential to cause infection, and the doctor could use the identity of the bacterium to decide which antibiotic to use.
Cultures are especially important when dealing with drug resistant bacteria, as doctors want to quickly be able to identify the best medication to use. If a bacterium is resistant to a particular drug, valuable time could be wasted treating the patient with the wrong medication, and this would be extremely unfortunate. Such cultures are also used to track the development of drug resistant bacteria, especially in hospitals, where there is concern that such bacteria could be evolving at a very rapid rate.
Cultures are generally grown by pathologists in a lab. Pathologists study the process and mechanics of disease, and they draw upon their considerable experience and training to grow cultures reliably and to identify the organisms which emerge. Pathologists are typically assisted by lab technicians and other personnel who help to keep records in the lab while keeping the lab running smoothly and efficiently.
If a doctor is pretty certain he or she is dealing with a bacterial infection, they will usually order a "culture and sensitivity." This means, as soon as the culture is complete, then the lab tech will immediately do a sensitivity test on the bacteria to see what will knock them out.
I remember having a terrible case of bronchitis. A Z-pack didn't do much, so the doc ordered a culture and sensitivity. Based on those results, he put me on Levaquin, which finally knocked out the infection. It was a relief when I could finally tell the antibiotics had kicked in.
My mom is a retired lab tech and when we got sore throats, she would invariably do a strep culture on us. In the dark ages, they had to wait 24 hours to see if the culture "grew" anything. Now, I think the wait is like seven minutes or so.
She stuck two long cotton swabs down our throats and scraped around. It was a very uncomfortable, if brief, process. The process is the same, unfortunately, but the results come back much faster.
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