- Primary pathogens (Staphylococcus aureus (including bullous impetigo) · Group A Streptococcus (Streptococcus pyogenes) · often mixed in non-bullous impetigo)
- Clinical context (Few localized lesions without systemic toxicity — topical therapy is treatment of choice after gentle cleansing (IDSA strong, high))
First-line therapy
Mupirocin • topical
Duration: 5 days · Apply thin layer to affected lesions BID after removing crusts with soap and water — IDSA strong recommendation (bid × 5 days)
Fusidic acid • topical
Duration: 5 days · Apply thin layer TID where locally available (UK/Europe) — rising fusidic acid resistance limits use; mupirocin preferred where available (NICE, IDSA)
- • Fusidic acid 2% cream: alternative topical agent where locally recommended (NICE, UK) when mupirocin unavailable or not tolerated — not first-line in North America (IDSA prefers mupirocin or retapamulin).
- • Retapamulin 1% ointment BID × 5 days: IDSA-equivalent topical option — no MRSA coverage; consider when mupirocin resistance suspected (IDSA, AAFP 2026).
- • Switch to systemic therapy if no improvement in 3–5 days, numerous lesions develop, bullous/ecthyma features, lymphadenopathy, or household outbreak (IDSA, StatPearls).
- • Oral cephalexin: not for typical localized disease — reserve for extensive impetigo variant (IDSA).
- • Nasal mupirocin decolonization: consider for recurrent impetigo with S. aureus nasal carriage in selected cases — not routine first episode (AAP, StatPearls).
Clinical notes
- • Localized disease: limited number of lesions (commonly ≤5 non-bullous lesions), no systemic signs, no deep ecthyma — topical antibiotics equivalent to oral for uncomplicated cases (IDSA, NICE, CPS).
- • Topical therapy preferred: mupirocin 2% BID × 5 days after gentle crust removal — avoids systemic antibiotics and resistance pressure when effective (IDSA strong, high).
- • Hygiene to reduce transmission: handwashing, avoid sharing towels/linens, wash clothing and bedding, keep lesions covered, avoid scratching; child may return to school/daycare after 24 h of appropriate antibiotic therapy (AAP, NICE).
- • MRSA coverage with topical therapy: mupirocin covers most CA-MRSA; retapamulin does not cover MRSA — switch to oral clindamycin or TMP/SMX strategy if MRSA confirmed and failing topical therapy (IDSA, CPS).
- • Reassess at 3–5 days — progression, satellite lesions, or lack of improvement warrants systemic antibiotics or culture (IDSA, AAFP).
- • IDSA — Practice guidelines for skin and soft tissue infections (impetigo) (2014)
- • AAP Red Book — Impetigo and staphylococcal skin infections (2024)
- • NICE — Impetigo antimicrobial prescribing guideline (2020)
+ 3 more
- • CPS — Community-associated bacterial SSTI in children (2024)
- • ESPID — Skin infection guidance (2024)
- • AAFP — Impetigo rapid evidence review (2026)