Antimicrobial Resistance

Antimicrobial resistance is the loss of antibiotic effectiveness as bacteria adapt. In eczema the organism that matters is Staphylococcus aureus. It colonises most children with Atopic Dermatitis and is repeatedly exposed to the same topical antibiotics. DermNet notes that staph is increasingly resistant to penicillins, macrolides (Erythromycin, Clarithromycin) and tetracyclines. Resistance to beta-lactams defines MRSA, which is 4–13 times more common among AD isolates than in healthy people (Ogonowska 2021).

Staphylococcus aureus [relates] Antimicrobial Resistance Antimicrobial Resistance [causes] MRSA

Topical overuse drives it. For Fusidic Acid, a UK/Irish genome study found resistance about 2.5 times more frequent in staph from children with AD than in healthy carriers. It arose through repeated independent fusA mutations that point to prior drug exposure, much of it from steroid–fusidic combinations such as Fucidin H (Harkins, BJD 2018). For Mupirocin, 31.3% of S. aureus isolates in a New York paediatric dermatology clinic were resistant. Prior mupirocin use was the only independent risk factor (OR 19.2–26.5). 68.2% of MRSA isolates from children with AD were mupirocin-resistant (Antonov, AAC 2015). New Zealand moved mupirocin back to prescription-only after its over-the-counter years saw resistance rise (DermNet). The Cochrane review rated the trial evidence on resistance as very low quality, so the signal comes from observational surveillance rather than RCTs.

Fusidic Acid [causes] Antimicrobial Resistance Mupirocin [causes] Antimicrobial Resistance Fucidin H [causes] Antimicrobial Resistance

Stewardship in toddler eczema care. NICE NG190 says not to routinely give topical or oral antibiotics for infected eczema in a well child, and to keep Emollient Therapy and Topical Corticosteroids going. If an antibiotic is used, fusidic acid is for localised infection only, for 5–7 days, taking account of previous topical antibiotic use. NICE NG153 puts the antiseptic Hydrogen Peroxide Cream first for localised impetigo, says not to combine topical and oral antibiotics, and warns that extended or recurrent fusidic acid or mupirocin use “may increase the risk” of resistance. Both guidelines reserve swabs for infections that are not improving or keep coming back, and suggest Decolonisation for frequent recurrences. For parents, this means no leftover antibiotic tubes, no antibiotic creams for flares without signs of infection, finishing the prescribed course, and controlling the eczema itself. Repeated infections are a reason for review or referral, not for another tube.

NICE NG190 [regulates] Antimicrobial Resistance Hydrogen Peroxide Cream [prevents] Antimicrobial Resistance Topical Corticosteroids [prevents] Antimicrobial Resistance

Connections

• NICE NG190 — rationale against routine antibiotics, source: NICE NG190
• NICE NG153 — no topical+oral combination; limit repeat courses, source: NICE NG153
• Fusidic Acid — fusA resistance enriched in AD children, source: Harkins BJD 2018
• Mupirocin — 31% resistance; prior use OR ~26, source: Antonov AAC 2015
• MRSA — beta-lactam resistance, over-represented in AD, source: Ogonowska 2021
• Fucidin H — combination steroid–fusidic use as driver, source: Harkins BJD 2018
• Hydrogen Peroxide Cream — antiseptic alternative with no known resistance, source: Crystacide SmPC
• Staphylococcus aureus — organism under selection, source: DermNet 2015
• Decolonisation — for recurrent infection, after swab, source: NICE NG190