In: Biology
What is the name of the medium that throat cultures are often streaked on?
What you are testing for with these plates?
A throat culture is a microbiological laboratory diagnostic procedure that evaluates for the presence of disease-causing bacterial or fungal microorganism in the throat. Bacterial sample from the throat is collected by swabbing the throat (throat swab).
Precisely, throat culture is performed to test the presence or absence of beta-hemolytic streptococci, bacteria that causes strep throat. The test is performed to evaluate the throat infection(sore throat) is viral or bacterial in nature.
Streptococcus pyogenes is cultivated on growth media that requires additional nutrients which is not provided by general purpose medium like nutrient agar and TSA. Therefore throat swab from suspected individual is streaked on Blood agar medium. To select only S. pyogenes throat swab is cultured on crystal violet blood agar medium.
Blood agar is an enriched growth medium that contains general nutrients and 5% sheep blood(defibrinated blood). Blood in the medium provide specific nutrient for the growth of the fastidious bacteria and crystal violet prevent the growth of other bacteria and promotes only the growth of Streptococcus pyogenes.
Most of the time, causative organisms for the sore throat is virus. Thus the swab is tested, and if the bacteria Streptococcus pyogenes is absent in the swab then unnecessary antibiotic will not be prescribed for the viruses that do not respond to them.