Treatment of Preseptal and Orbital Cellulitis Antibiotics Preseptal cellulitis In patients with preseptal cellulitis, initial therapy should be directed against sinusitis pathogens (S pneumoniae, nontypeable H influenzae, S aureus, Moraxella catarrhalis); however, in areas where methicillin-resistant S aureus is prevalent, clinicians should add appropriate antibiotics (eg, clindamycin, trimethoprim / sulfamethoxazole, or doxycycline for oral treatment and vancomycin for inpatient treatment).