Cephalexin Efficacy and Alternative Recommendations for Bullous Impetigo

Microbiologic Activity

Cephalexin exhibits excellent in‑vitro activity against methicillin‑susceptible Staphylococcus aureus (MSSA), the predominant pathogen in bullous impetigo. 1, 2

When methicillin‑resistant S. aureus (MRSA) is suspected or confirmed, oral clindamycin (30–40 mg/kg/day in 3–4 divided doses) or trimethoprim‑sulfamethoxazole should be used instead of cephalexin. 2
Children presenting with systemic inflammatory response syndrome (e.g., fever, tachycardia, tachypnea) may require parenteral antimicrobial therapy rather than oral cephalexin. 2
In patients with an immediate‑type hypersensitivity to penicillins, cephalosporins such as cephalexin should be avoided; clindamycin is the recommended alternative. 1, 2

A pharmacokinetic‑guided high‑dose regimen of 45 mg/kg per dose (maximum 1.5 g) administered three times daily has demonstrated a 99 % cure rate for MSSA bone and joint infections; for a 13.6 kg child this corresponds to approximately 612 mg per dose. 1