A medical laboratory is diagnostic. The information the lab finds and reports to the doctor will help the doctor to diagnose and treat the patient's problem.
Any drainage from your body can be studied in a medical laboratory. Specially trained, educated, and certified lab techs test the drainage to see what kind of bacteria is causing the infection. Once the doctor has this information, proper treatment can be started. Nasal, throat, eye, ear, genital, urine, fecal, wounds, blood, extracted spinal fluid - all these sources can be cultured and grown and studied in the micro department. A fun place to work!
GRAM STAIN. A little bit of the infected sample is rolled in a thin layer onto a small glass slide and sent to the lab. There, it is stained with a special stain called the Gram stain. The lab tech looks at the slide under the microscope, looking for shape and color of any bacteria found. This can sometimes be tricky because elongated cocci can look like rods, and short fat rods can resemble cocci. A pale blue can look almost pink and a dark pink can resemble almost blue. Only an experienced, educated lab tech should read and report Gram stains because of the many artifacts seen on a slide. Once the shape and color of the bacteria has been determined, the bacteria can be classified. Different classes of bacteria respond to different antibiotics.
CULTURE. The lab tech swabs the material onto different types of agar and then places the agar plates into incubators. The plates are checked daily until something starts to grow. This can take 1-3 days, or more depending on the source of the infection. If something does grow, the lab tech is able to identify it. This information helps the doctor determine proper treatment for the patient.
SENSITIVITY. If an abnormal bacteria grows out in the CULTURE, the lab can test the bacteria with little disks that have been saturated with different antibiotics. They place the specimen into the incubator once again and see which antibiotic disk will stop the growth of the bacteria. This can take a couple days again. This will tell the doctor exactly which antibiotic will kill the infection. Sensitivity tests are not done on normal bacteria.
The above tests are done on bacterial infections. A fungus, such as yeast, can be grown in a medical micro lab also. Viruses, however, require special testing and are not grown in a medical micro lab.
After working 20 years as an ASCP certified Med Tech, I switched careers to teach science in an inner-city high school. I've written a memoir about the joys of teaching and the obstacles I fought. No Child Left Behind? The True Story of a Teacher's Quest by Elizabeth Blake on http://www.BarnesandNoble.com and Amazon. Drugs, gangs, a riot, shootings, murdered students, abusive principals - all contributed to the stress which eventually drove me from the students I loved.
The book celebrates triumph over adversity. To read the first page, visit http://www.elizabethblakeonline.com