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Author: Abdul-Ghani Kibbi, MD, Chairman and Professor, Department of Dermatology, American University of Beirut Medical Center, Lebanon

Coauthor(s): Zenus Saleh, MD, Staff Physician, Department of Dermatology, American University of Beirut Medical Center; Fadi Haddad, MD, Specialist, Divisions of Dermatology, Tawam Hospital, United Arab Emirates

Editors: Robin Travers, MD, Professor, Department of Dermatology, Boston University School of Medicine; Richard P Vinson, MD, Assistant Clinical Professor, Department of Dermatology, Texas Tech University School of Medicine; Consulting Staff, Mountain View Dermatology, PA; Jeffrey Meffert, MD, Assistant Clinical Professor of Dermatology, University of Texas Health Science Center-San Antonio; Catherine Quirk, MD, Clinical Assistant Professor, Department of Dermatology, Brown University; Dirk M Elston, MD, Director, Department of Dermatology, Geisinger Medical Center

Author and Editor Disclosure

Synonyms and related keywords: Corynebacterium minutissimum, C minutissimum, Corynebacterium afermentans, C afermentans

Background

Erythrasma is a chronic superficial infection of the intertriginous areas of the skin. The incriminated organism is Corynebacterium minutissimum, which usually is present as a normal human skin inhabitant. In 1996, Corynebacterium afermentans was reported in one case.

Pathophysiology

Corynebacteria invade the upper one-third of the stratum corneum; under favorable conditions such as heat and humidity, these organisms proliferate. The stratum corneum is thickened. The organisms are seen in the intercellular spaces as well as within cells, dissolving keratin fibrils. The coral red fluorescence of scales seen under Wood light is secondary to the production of porphyrin by these diphtheroids.

Frequency

International

The incidence of erythrasma is reported to be around 4%. This infection is observed all over the world; the widespread form is found more frequently in the subtropical and tropical areas than in other parts of the world.

Mortality/Morbidity

Erythrasma is usually a benign condition. However, it may become widespread and invasive in predisposed and immunocompromised individuals; this is very rare in immunocompetent hosts. In such individuals, this organism has caused infections other than erythrasma. These include abscess formation (3 cases), intravascular catheter–related infections (3 cases), primary bacteremia (3 cases), peritoneal catheter–related infections (2 cases), endocarditis (1 case), and pyelonephritis (1 case).

Race

The incidence is higher in black people.

Sex

Both sexes are equally affected; however, the crural form is more common in men.

Age

The incidence of erythrasma increases with age, but no age group is immune to the disease. The youngest patient reported to have this condition is a 1-year-old infant.



History

  • Dark discoloration is usually limited to body folds that are naturally moist and occluded.
  • Infection commonly is asymptomatic, but it can be pruritic.
  • Duration ranges from months to years.
  • Widespread involvement of trunk and limbs is possible.

Physical

  • The typical appearance is well-demarcated, brown-red macular patches. The skin has a wrinkled appearance with fine scales (Image 1).
  • Infection commonly is located over inner thighs, crural region, scrotum, and toe webs.
  • Axillae, submammary area, periumbilical region, and intergluteal fold are less commonly involved.
  • Toe web lesions appear as maceration.

Causes

  • C minutissimum, a member of the normal skin flora, is the causative agent.
    • The bacterium is a lipophilic, gram-positive, non–spore-forming, aerobic, and catalase-positive diphtheroid.
    • C minutissimum ferments glucose, dextrose, sucrose, maltose, and mannitol.
  • Predisposing factors include the following:
    • Excessive sweating/hyperhidrosis
    • Delicate cutaneous barrier
    • Obesity
    • Diabetes mellitus
    • Warm climate
    • Poor hygiene
    • Advanced age
  • Other immunocompromised states



Acanthosis Nigricans
Candidiasis, Cutaneous
Contact Dermatitis, Allergic
Contact Dermatitis, Irritant
Intertrigo
Psoriasis, Plaque
Seborrheic Dermatitis
Tinea Corporis
Tinea Cruris
Tinea Pedis

Other Problems to be Considered

Pityriasis versicolor
Pruritus ani



Lab Studies

  • Wood light examination reveals coral-red fluorescence of lesions. Results may be negative if the patient bathed prior to presentation.
  • Gram staining reveals gram-positive filamentous rods.
  • In culture media composed of 20% fetal bovine serum, 2% agar, 78% tissue culture medium #199, and 0.05% tris, the organisms grow as nonhemolytic, 1- to 1.5-mm smooth colonies.

Histologic Findings

The diphtheroid bacteria are present in the horny layer as rods and filaments.



Medical Care

Recently, photodynamic therapy has been reported.



The goals of pharmacotherapy are to reduce morbidity, eradicate the infection, and prevent complications.

Drug Category: Anti-infectives

Antibacterial and/or antifungal agents are used to eradicate C minutissimum and possible concomitant infection. Erythromycin is the DOC. Infection may be treated with topical and/or oral agents. Therapy must be comprehensive and cover all likely pathogens in the context of this clinical setting. C minutissimum is generally susceptible to penicillins, first-generation cephalosporins, erythromycin, clindamycin, ciprofloxacin, tetracycline, and vancomycin. However, multiresistant strains have been isolated.

Drug NameErythromycin (E.E.S., E-Mycin, Ery-Tab)
DescriptionDOC that inhibits bacterial growth, possibly by blocking dissociation of peptidyl t-RNA from ribosomes, causing RNA-dependent protein synthesis to arrest.
In children, age, weight, and severity of infection determine proper dosage. When bid dosing is desired, half-total daily dose may be taken q12h. For more severe infections, double the dose.
Adult Dose250 mg PO qid or 500 mg PO bid for 7-14 d
2-4% solution: Apply to affected area bid for 4-6 wk
Pediatric Dose30-50 mg/kg/d PO bid for 7-10 d
2-4% solution: Apply to affected area as in adults
ContraindicationsDocumented hypersensitivity; hepatic impairment
InteractionsCoadministration may increase toxicity of theophylline, digoxin, bromocriptine, alfentanil, cisapride, felodipine, ergotamine, midazolam, triazolam, methylprednisolone, carbamazepine, and cyclosporine; may potentiate anticoagulant effects of warfarin; coadministration with lovastatin and simvastatin increases risk of rhabdomyolysis; cimetidine may increase levels of erythromycin; arrhythmias and increases in QTc intervals occur with disopyramide; no interactions reported with topical dosage form
PregnancyB - Usually safe but benefits must outweigh the risks.
PrecautionsCaution in liver disease; estolate formulation may cause cholestatic jaundice; GI adverse effects are common (give doses pc); discontinue use if nausea, vomiting, malaise, abdominal colic, or fever occur; 2-4% solution, discontinue if irritation or sensitivity occur

Drug NameClarithromycin (Biaxin)
DescriptionInhibits bacterial growth, possibly by blocking dissociation of peptidyl t-RNA from ribosomes, causing RNA-dependent protein synthesis to arrest.
Adult Dose1 g PO once
Pediatric Dose15 mg/kg PO once
ContraindicationsDocumented hypersensitivity; coadministration of pimozide or cisapride
InteractionsToxicity increases with coadministration of fluconazole, astemizole, and pimozide; clarithromycin effects decrease and GI adverse effects may increase with coadministration of rifabutin or rifampin; may increase toxicity of anticoagulants, cyclosporine, tacrolimus, digoxin, omeprazole, carbamazepine, ergot alkaloids, triazolam, HMG CoA-reductase inhibitors; cardiac arrhythmias may occur with coadministration of cisapride; plasma levels of certain benzodiazepines may increase, prolonging CNS depression; arrhythmias and increase in QTc intervals occur with disopyramide; coadministration with omeprazole may increase plasma levels of both agents
PregnancyC - Safety for use during pregnancy has not been established.
PrecautionsCoadministration with ranitidine or bismuth citrate is not recommended with CrCl <25 mL/min; give half dose or increase dosing interval if CrCl <30 mL/min; diarrhea may be sign of pseudomembranous colitis; superinfections may occur with prolonged or repeated antibiotic therapies

Drug NameFusidic acid (Zeta)
DescriptionTopical antibacterial that inhibits bacterial protein synthesis, causing bacterial death.
Use 2% cream.
Adult DoseApply to affected area bid for 2 wk
Pediatric DoseApply as in adults
ContraindicationsDocumented hypersensitivity
InteractionsNone reported
PregnancyB - Usually safe but benefits must outweigh the risks.
PrecautionsDiscontinue if irritation or sensitivity occur

Drug NameMiconazole (Femazole, Lotrimin, Monistat)
DescriptionDamages fungal cell wall membrane by inhibiting biosynthesis of ergosterol. Membrane permeability is increased causing nutrients to leak out, resulting in fungal-cell death.
The lotion is preferred in intertriginous areas. If the cream is used, apply sparingly to avoid maceration effects.
Use 2% cream.
Adult DoseApply to affected area bid for 2 wk
Pediatric DoseApply as in adults
ContraindicationsDocumented hypersensitivity
InteractionsNone reported
PregnancyC - Safety for use during pregnancy has not been established.
PrecautionsIf sensitivity or chemical irritation occurs, discontinue use; use only externally; avoid contact with eyes

Drug NameBenzoic acid 6%, salicylic acid 3% (Whitfield's ointment)
DescriptionTreats infection and inflammation associated with erythrasma.
Adult DoseApply to affected area bid for 4 wk
Pediatric DoseNot established
ContraindicationsDocumented hypersensitivity
InteractionsNone reported
PregnancyC - Safety for use during pregnancy has not been established.
PrecautionsFor external use only

Drug NameClindamycin (Cleocin)
DescriptionHas a bacteriostatic effect; it interferes with bacterial protein synthesis similarly to erythromycin and chloramphenicol by binding to 50S subunit of bacterial ribosome.
Adult DoseApply 2% aqueous solution tid for 1 wk
Pediatric DoseNot established
ContraindicationsDocumented hypersensitivity
InteractionsInteracts with opiates and diphenoxylate plus atropine, resulting in slowing of peristalsis; may enhance action of neuromuscular blocking agents; coadministration with erythromycin leads to increased level of clindamycin
PregnancyD - Unsafe in pregnancy
PrecautionsAllergic skin reactions, severe colitis, neutropenia, and polyarthritis

Drug NameTetracycline (Achromycin)
DescriptionInhibits cell growth by inhibiting mRNA translation. Binds to 16S part of 30S ribosomal subunit and prevents amino-acyl tRNA from binding to A site of ribosome. Binding is reversible in nature.
Adult Dose250 mg qid for 14 d
Pediatric DoseNot established
ContraindicationsDocumented hypersensitivity
InteractionsInterferes with bactericidal action of penicillins, renders oral contraceptives less effective, and potentiates effects of warfarin
PregnancyB - Usually safe but benefits must outweigh the risks.
PrecautionsEsophagitis, allergic reactions, phototoxic reactions, renal toxicity, hemolytic anemia, pseudotumor cerebri, vestibular toxicity, and tooth discoloration



Complications

  • Fatal septicemia in immunocompromised patients
  • Infective endocarditis in valvular heart disease
  • Post-surgical wound infection

Prognosis

  • Prognosis is excellent; however, the condition tends to recur if the predisposing factors are not eliminated.

Patient Education

  • Patients should be instructed to keep the area dry.



Medical/Legal Pitfalls

  • Failure to consider diabetes in patients with recurrent erythrasma
  • Failure to investigate for other coexistent infections

Special Concerns

  • Immunosuppressed patients and the risk of complications are of special concern.
  • Evaluate and treat possible concomitant infection.
  • Suspect diabetes in recurrent erythrasma.
  • Address and modify risk factors for successful treatment.



Media file 1:  Lichenification and hyperpigmentation are common. The skin occasionally has a wrinkled appearance with scales. KOH test results are negative. Courtesy of Michael Bryan, MD.
Click to see larger pictureClick to see detailView Full Size Image
Media type:  Photo

Media file 2:  Under Wood lamp examination, the porphyrins produced by the bacteria fluoresce with a coral pink color. A small focus is visible on this photo. If the patient recently has bathed, the pigment may be washed away. In suspicious cases, a repeat examination the following day may be necessary. Courtesy of Michael Bryan, MD.
Click to see larger pictureClick to see detailView Full Size Image
Media type:  Photo



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Erythrasma excerpt

Article Last Updated: Feb 27, 2007