2. Anaerobic utilization of glucose.
Inoculate tube of carbohydrate fermentation medium containing glucose (0.5%).
Immediately inoculate each tube heavily with wire loop. Make certain inoculum reaches bottom of tube.
Cover surface of agar with layer of sterile paraffin oil at least 25 mm thick. Incubate 5 days at 37°C.
Acid is produced anaerobically if indicator changes to yellow throughout tube, indicating presence of S. aureus.
Run controls simultaneously (positive and negative cultures and medium controls).