Pearls and Pitfalls Cellulitis that is associated with purulent drainage is commonly associated with Staphylococcus Aureus compared to non-purulent cellulitis that is more commonly β hemolytic streptococcus. Antimicrobial therapy should be directed at the organism in question. Cellulitis may not appear as red and can span the gamut from pale to violet coloration in deeper infections. Pain is not always present particularly in immunocompromised patients. Cultures from peripheral blood, needle aspirates, skin biopsies, and surgical specimens have a relatively low yield. They should be considered however in patients with purulent drainage, those who failed outpatient therapy, or immunocompromised patients.