Dermatology/Skin infection antimicrobials

Skin & soft-tissue infection drugs

also: flucloxacillin cellulitis · fusidic acid impetigo · oral acne antibiotics · aciclovir shingles

Overview

Antimicrobials for skin/soft-tissue infection, in context — cellulitis, impetigo, the oral acne antibiotics, and the cutaneous antivirals.

Mechanism

Pathogen-directed: flucloxacillin (anti-staphylococcal penicillin) and clarithromycin/doxycycline cover the Staph/Strep of cellulitis. Topical fusidic acid / oral flucloxacillin for impetigo. Oral tetracyclines (lymecycline/doxycycline) for inflammatory acne (anti-C. acnes + anti-inflammatory). Aciclovir for cutaneous herpes. (Full class mechanisms: Antimicrobials section.)

Indications

Cellulitis / erysipelas
Impetigo
Moderate acne (oral antibiotic step)
Cutaneous HSV/VZV (shingles, eczema herpeticum)

The agents

Flucloxacillincellulitis/impetigo

PO/IV

First-line (Staph/Strep); clarithromycin or doxycycline if penicillin-allergic.

Fusidic acid (topical)localised impetigo

Topical for very localised; hydrogen peroxide cream is NICE first-line for non-bullous.

Lymecycline / doxycycline (oral)acne

Moderate acne; NOT with oral isotretinoin (intracranial hypertension); avoid pregnancy/<12.

Aciclovircutaneous antiviral

PO/IV

Shingles (within 72 h), eczema herpeticum (IV — dermatological emergency).

Co-amoxiclavbites/diabetic foot

Human/animal bites (Pasteurella/anaerobes).

Adverse effects

Flucloxacillin: cholestatic hepatitis (delayed)serious

Oral tetracyclines: photosensitivity, oesophagitiscommon

Aciclovir: AKI if dehydrated (IV)common

Cautions & contraindications

Tetracyclines with oral isotretinoinall

Benign intracranial hypertension.

Tetracyclines in pregnancy / <12pregnancy

Flucloxacillin if previous flucloxacillin jaundiceall

Interactions

Tetracyclines: calcium/iron/antacids reduce absorption

Monitoring & kinetics

Mark cellulitis border; review impetigo exclusion (school),Eczema herpeticum → urgent IV aciclovir + ophthalmology if periocular

Topical for very localised; oral/IV per severity. See Antimicrobials for full pharmacology.

Source: NICE NG141 — Cellulitis · NICE NG153 — Impetigo