Final answer:
Before interpreting bacteremia characterized by grape-like gram-positive clusters, it is crucial to review the patient's medical history to identify underlying conditions and guide treatment, given that these clusters typically indicate a Staphylococcus aureus infection(option c).
Step-by-step explanation:
If a patient presents with purulent cellulitis and bacteremia characterized by grape-like gram-positive clusters in his blood, the first thing you would want to ensure before interpreting the results is to c) Review the patient's medical history.
Doing so is vital for understanding any underlying conditions or previous infections that may influence the current situation and the choice of treatment. Additionally, it is important to recognize that these grape-like clusters are indicative of Staphylococcus aureus, one of the most common causes of skin infections, which may be resistant to certain antibiotics and can lead to serious complications if not adequately treated.