Secondary Bacterial Infections and Nasal Colonization in Scabies and Atopic Dermatitis

Participants with dermatologist-confirmed scabies or atopic dermatitis and active impetiginized skin lesions will undergo clinical assessment and microbiological sampling. A superficial swab will be obtained from the infected skin lesion and a nasal swab will be obtained from the nasal vestibules. Healthy controls will undergo nasal sampling only. Cultures will be evaluated for Staphylococcus aureus, Streptococcus pyogenes, and other bacterial isolates. Antimicrobial susceptibility testing will be performed according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidance. Skin and nasal isolates will be compared at the species level and by antimicrobial resistance profile. Clinical data include age, sex, disease duration, comorbidities, recent treatments, itch severity using a 0-10 visual analog scale, and lesion morphology, location, number, and excoriation. Patients will be contacted on days 7 and 14 to assess clinical response, new lesion development, change in itch severity, treatment adherence, and local or systemic adverse events.

Inclusion criteria

• Scabies group: dermatologist-confirmed scabies and an active impetiginized skin lesion.
• Atopic dermatitis group: dermatologist-confirmed atopic dermatitis and an active impetiginized skin lesion.
• Healthy control group: no inflammatory skin disease or clinical signs of infection.
• Written informed consent (and appropriate parent/guardian permission when applicable).

Exclusion criteria

• Systemic or topical antibiotic use within the previous 14 days.
• Active nasal infection or nasal symptoms.
• History of nasal surgery or anatomic nasal deformity.

TEST DRAFT NOTE: The source protocol contains wording that may conflict with inclusion of healthy controls; the final eligibility text must be reconciled with the ethics-approved protocol before release.