Polymyxin-coagulase-deoxyribonuclease-agar: a selective isolation medium for Staphylococcus aureus

Area of Science:

• Microbiology
• Bacteriology

Background:

• Staphylococcus aureus is a significant human pathogen.
• Coagulase-positive strains are typically virulent.
• Understanding bacterial byproducts aids in identification and characterization.

Purpose of the Study:

• To investigate the formation of fibrin halos around Staphylococcus aureus colonies.
• To detect deoxyribonuclease (DNase) production in coagulase-positive Staphylococcus aureus.

Main Methods:

• Culturing coagulase-positive Staphylococcus aureus colonies on agar plates.
• Observing for the development of fibrin halos surrounding the colonies.
• Utilizing a developing solution with 1 mg/ml methyl green to detect DNase activity.

Main Results:

• Fibrin halos were observed to develop around the colonies of coagulase-positive Staphylococcus aureus.
• Deoxyribonuclease production was successfully detected in these bacterial colonies using the specified methyl green solution.

Conclusions:

• The presence of fibrin halos is a characteristic feature associated with coagulase-positive Staphylococcus aureus.
• Methyl green serves as an effective indicator for detecting deoxyribonuclease activity in Staphylococcus aureus.