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erythrasma
From Greek 'red spot'.
Chronic superficial bacterial infection of the skin.
Etiology:
1) Corynebacterium minutissimum
2) predisposing factors
a) diabetes
b) warm, humid climate
c) prolonged occlusion of skin
d) maceration
Clinical manifestations:
1) macules, generally large & scaling, sharply marginated
2) pink/red to brownish red in color
3) sites of predilection
a) intertriginous areas of toes, groin & axillae
b) skin folds: groin, subpanniculus, intergluteal, inframammary
4) mimics dermatophyte infection
5) generally asymptomatic, but may cause burning sensation or pruritus
6) interdigital lesions are erosive with collarette-like scale
7) lesions may consist of confluent patches or scattered, discrete lesions
8) skin often has thin, wrinkled appearance similar to cigarette paper
* images [4]
Laboratory:
1) Wood's lamp: coral-red fluorescence
- may not be present if patient has recently bathed
2) direct microscopic examination of 10% KOH-treated skin scrapings not helpful [2]
3) bacterial culture:
- rule out Staphylococcus aureus or group A streptococcal infection
Differential diagnosis:
1) dermatophytosis
2) cutaneous candidiasis
3) pityriasis versicolor
4) inverse pattern psoriasis
5) seborrheic dermatitis
6) pitted keratolysis (Micrococcus sedentarius)
- manifests as scale & pitting of the skin surface
- involved areas are white when stratum corneum is fully hydrated
- toe webs, balls or heel of foot in contact with shoe
- foot odor (malodorous)
- hyperhidrosis
- no hyphae in 10% KOH preparations from skin scrapings
- Wood's lamp: negative for coral-red fluorescence (erythrasma)
7) intertrigo
Management:
- topical fusidic acid is the most effective treatment [3]
- clarithromycin single dose with better patient medication compliance
- erythromycin inferior to single dose clarithromycin
- topical erythromycin solution BID for 7 days
- erythromycin 250 mg PO QID for 14 days
- topical clindamycin [4]
- oral tetracycline [4]
- benzoyl peroxide (2.5%) gel; apply daily for 7 days
- prevention:
a) benzoyl peroxide
b) correct predisposing causes
- relapses occur if predisposing causes are not corrected
Related
Corynebacterium minutissimum
General
bacterial infection
skin infection
References
- Color Atlas & Synopsis of Clinical Dermatology, Common
& Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY,
1997, pg 616
- Medical Knowledge Self Assessment Program (MKSAP) 17, 18, 19
American College of Physicians, Philadelphia 2015, 2018, 2022.
- Avci O, Tanyildizi T, Kusku E.
A comparison between the effectiveness of erythromycin,
single-dose clarithromycin and topical fusidic acid in the
treatment of erythrasma.
J Dermatolog Treat. 2013 Feb;24(1):70-4
PMID: 21923567
- DermNet NZ. Erythrasma (images)
http://www.dermnetnz.org/bacterial/erythrasma.html
- Forouzan P, Cohen PR.
Erythrasma revisited: diagnosis, differential diagnoses, and comprehensive
review of treatment.
Cureus. 2020;12:e10733.
PMID: 33145138