Identification of bacteria

How do the bacteriologists decide which bacteria is causing the postoperative wound infection?

In about 130 years the bacteriologists used the relatively simple method to smear the pus or the swabs from the wound on to special substrate. The substrate is either fast, gelatin-like substance agar mixed with blood; or liquid, a kind of nutritious soup in a bottle.

Pus containing Staphylococcus aureus bacteria was smeared on the surface of the blood-agar plate. The blood-agar plate is within a glass dish and is covered by another dish to prevent downfall of other bacteria from the air. The whole culture is grown for at least 2 days in a constant temperature (32-37 degrees Celsius). (more…)