Final answer:
Correct identification of S. aureus and Streptococcus pyogenes cellulitis requires laboratory tests, as both can cause similar clinical symptoms.
Step-by-step explanation:
It is possible to distinguish between S. aureus cellulitis and Streptococcus pyogenes cellulitis by analyzing the bacterial culture. S. aureus can be confirmed with a passive agglutination test and is recognizable under the microscope by its grapelike clusters and reaction to a coagulase test. Conversely, S. pyogenes, which belongs to the Group A streptococci, can be identified as catalase-negative, beta hemolytic, and susceptible to 0.04 units of bacitracin. While examining the patient's symptoms might offer initial clues, definitive differentiation requires laboratory tests since both bacteria can cause conditions with overlapping clinical presentations, such as cellulitis and erysipelas.