Question

A patient comes to you with a "PUS" sample and asks you to isolate & identify the Staphylococcus aureus form this sample then how you can isolate and identify the Staphylococcus aureus from the "PUS" sample. Kindly explain in sequence step by step.

Answer 1

Answer: Staphylococcus aureus can be isolated from the pus sample through the following steps:

--> Step 1: Describe the appearance of the specimen

--> Step 2: Examine the specimen microscopically

--> Step 3: Culture and report your observations.

--> Step 4: Biochemical testing

Explanation: Staphylococcus aureus are gram positive cocci bacteria that can be isolated from pus samples.Pus samples, which may come from wounds, abscess, burns or sinuses, are the type of samples which do not contain microorganisms and should not contain contaminants providing an aseptic collection technique and sterile container are used.

Staphylococcus aureus can be isolated from the pus sample through the following steps:

--> Step 1: White, yellow, brown, red, or black granules of varying size, shape, and consistency may be found in pus draining from

sinuses while describing the appearance of the pus sample.

--> Step 2: Here the specimen is examined microscopically after being stained with a staining technique called Gram staining. This step is done before culture to know the type of medium to use after gram positive cocci is microscopically seen.

--> Step 3: there are different cultures media that can be used to inoculate and culture a pus specimen. Since we are to isolate staphylococcus aureus, a selective and differential media known as Mannitol salt agar (MSA) is used. The presence of yellow colonies with yellow zone after incubation at 37°C indicate the presence of Staphylococcus aureus or species. There for the last confirmation test known as biochemical test is done.

--> Biochemical test: This is a chemical test that is done to identify a particular bacteria. For staphylococcus aureus, COAGULASE test is used to identify staphylococcus aureus which produces COAGULASE enzyme. A positive COAGULASE test is an indication of the presence of staphylococcus aureus as the bacterium isolate of the specimen.