Which antibiotic is the most appropriate choice for outpatient treatment of cellulitis when CA-MRSA is not suspected?

Cephalexin is the most appropriate choice for outpatient treatment of cellulitis when community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is not suspected. It is a first-generation cephalosporin antibiotic that is effective against common pathogens associated with cellulitis, particularly Streptococcus pyogenes and susceptible Staphylococcus aureus. Cephalexin's coverage of these organisms makes it an ideal choice for uncomplicated skin infections like cellulitis, especially in patients who do not have risk factors for CA-MRSA.

Doxycycline, while effective against CA-MRSA, is not the first-line treatment when there is no suspicion of these resistant organisms, and it tends to be reserved for cases where MRSA is a concern. Linezolid is typically used for more complicated infections or when there is a confirmed or highly suspected resistant infection. Terbinafine is primarily an antifungal medication, not typically indicated for bacterial cellulitis, which again underscores how cephalexin serves as a more suitable option for uncomplicated cellulitis when CA-MRSA is not involved.