You are in: eMedicine Specialties > Dermatology > FUNGAL INFECTIONS SporotrichosisArticle Last Updated: Feb 7, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 11
  Author: Scott D Miller, MD, Dermatologist and Dermatologic Surgeon, Department of Dermatology, Carolinas Dermatology Group, PA Scott D Miller is a member of the following medical societies: American Academy of Dermatology and American Society for Dermatologic Surgery Editors: Kathryn Schwarzenberger, MD, Associate Professor of Medicine, Division of Dermatology, University of Vermont College of Medicine; Consulting Staff, Division of Dermatology, Fletcher Allen Health Care; Richard P Vinson, MD, Assistant Clinical Professor, Department of Dermatology, Texas Tech University School of Medicine; Consulting Staff, Mountain View Dermatology, PA; Lester F Libow, MD, Dermatopathologist, South Texas Dermatopathology Laboratory; Catherine Quirk, MD, Clinical Assistant Professor, Department of Dermatology, Brown University; William D James, MD, Paul R Gross Professor of Dermatology, University of Pennsylvania School of Medicine; Vice-Chair, Program Director, Department of Dermatology, University of Pennsylvania Health System Author and Editor Disclosure Synonyms and related keywords: INTRODUCTIONSection 2 of 11
  BackgroundSporotrichosis is a subcutaneous or systemic infection caused by Sporothrix schenckii, a rapidly growing dimorphic fungus. The organism derives its name from R B Schenck, who first reported the infection in 1898. Sporothrix typically exists as a saprophytic mold on vegetative matter in humid climates worldwide. A dimorphic fungus, the organism exhibits mycelial forms at 25°C and a yeast form at 37°C. Cutaneous infection often results from a puncture wound involving thorns or other plant matter. Other more unusual reported causes include squirrel bites and trauma induced by liposuction. Any compromise of the skin barrier with subsequent seeding could potentially cause infection. Sporotrichosis usually occurs sporadically as isolated cases. Occasionally, groups of individuals are infected after being exposed to the organism. Since approximately the beginning of the 21st century, an outbreak of increasing numbers of cases has been occurring in Rio de Janeiro, Brazil. From 1998-2004, 759 culture-proven cases have been identified and treated, predominantly among women at a median age of 39 years and predominantly among those with domiciliary or professional contact with infected cats. An outbreak in the United States in 1988 affected 84 people who handled sphagnum moss. An unusually large outbreak occurred in Africa in the 1940s in more than 3000 miners who had frequent physical contact with wood timber supports. This contributed significantly to the current understanding of Sporothrix schenckii, its growth patterns, and its mechanisms of dissemination. PathophysiologySporotrichosis infections can be either cutaneous or extracutaneous. Cutaneous infections are most common and are subclassified into fixed cutaneous and lymphocutaneous. A few authors refer to a rarely included third subclass of cutaneous sporotrichosis in which diffuse cutaneous involvement occurs. Fixed cutaneous infections occur at the site of inoculation and remain confined entirely to the skin. Lymphocutaneous disease results from lymphangitic spread of an infection. Satellite lesions develop along the path of the lymphatic vessels (sporotrichoid spread) and associated lymphadenopathy occurs. Extracutaneous, or disseminated sporotrichosis, can present as pyelonephritis, orchitis, mastitis, synovitis, meningitis, or osseous infection. Sporotrichosis can cause a monoarthritis, typically involving the knee. Many affected individuals are immunosuppressed by alcoholism or HIV infection. Pulmonary involvement is rare. FrequencyUnited StatesThe incidence of sporotrichosis is unknown. As an unreported, sporadic disease, its incidence is difficult to estimate. The mold itself is endemic to the Missouri and the Mississippi River Valleys. InternationalSporotrichosis is the most common subcutaneous mycosis in South America. Most reported cases occur in Mexico, followed by the remaining Americas, Australia, Asia, and Africa. Sporotrichosis is rare in Europe. Mortality/MorbidityThe morbidity of cutaneous infections is generally low, although therapy can be prolonged and can have potentially serious adverse effects.
SexIn the past, males were affected more often than females due to occupational-related risks for puncture wounds. With the 1998 outbreak in Rio de Janeiro, Brazil, women with exposure to infected cats currently account for the predominant number of new cases. AgeSporotrichosis may occur in any age, but it typically affects adults, reflecting their more frequent participation in veterinary care, gardening, woodworking, and occupational situations in which puncture wounds may occur. CLINICALSection 3 of 11
HistoryMost patients relate a history of a recent prick injury at the site of infection. Clinical disease usually becomes apparent within 3 weeks of injury; however, the interval from injury to apparent infection may be as long as 6 months. The injuries are attributed to a variety of causes, including rose thorns, hay, sphagnum moss, conifer needles, mine timbers, and infected cats. The characteristic skin lesion is a dermal or subcutaneous nodule that may ulcerate. As the infection spreads along the regional lymphatic chain, satellite nodules develop along with associated regional lymphadenopathy. The infection may disseminate to cause systemic disease. Physical
CausesSporotrichosis is caused by S schenckii, a dimorphic fungus. DIFFERENTIALSSection 4 of 11
Leishmaniasis Mycobacterium Marinum Infection of the Skin Nocardiosis Syphilis
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| Drug Name | Amphotericin B (AmBisome) |
|---|---|
| Description | Produced by a strain of Streptomyces nodosus; can be fungistatic or fungicidal. Binds to sterols, such as ergosterol, in the fungal cell membrane, causing intracellular components to leak with subsequent fungal cell death. DOC for systemic disease, although more recent literature indicates itraconazole or terbinafine may replace amphotericin B as the DOC for systemic sporotrichosis. |
| Adult Dose | 800-2950 mg total dose slow IV infusion; 3-5 mg/kg/d IV of liposomal amphotericin B over approximately 120 min |
| Pediatric Dose | Administer as in adults |
| Contraindications | Documented hypersensitivity |
| Interactions | Antineoplastic agents may enhance the potential of amphotericin B for renal toxicity, bronchospasm, and hypotension; corticosteroids, digitalis, and thiazides may potentiate hypokalemia; the risk of renal toxicity is increased with cyclosporine |
| Pregnancy | B - Usually safe but benefits must outweigh the risks. |
| Precautions | Monitor renal function, serum electrolytes (eg, magnesium and potassium), liver function, CBC, and hemoglobin concentrations; resume the therapy at the lowest level (eg, 0.25 mg/kg) when the therapy is interrupted for > 7 d; hypoxemia, acute dyspnea, and interstitial infiltrates may occur in neutropenic patients receiving leukocyte transfusions (separate time of amphotericin infusion from time of leukocyte transfusion) |
| Drug Name | Itraconazole (Sporanox) |
|---|---|
| Description | Synthetic triazole antifungal agent that slows fungal cell growth by inhibiting cytochrome P-450-dependent synthesis of ergosterol, a vital component of fungal cell membranes. DOC for cutaneous disease and second DOC (likely to soon be first DOC) for systemic disease. |
| Adult Dose | 100 mg PO bid |
| Pediatric Dose | Administer as in adults |
| Contraindications | Documented hypersensitivity; coadministration with cisapride may cause adverse cardiovascular effects (possibly death) |
| Interactions | Antacids may reduce absorption; edema may occur with coadministration of calcium channel blockers (eg, amlodipine, nifedipine); hypoglycemia may occur with sulfonylureas; may increase tacrolimus and cyclosporine plasma concentrations when high doses are used; rhabdomyolysis may occur with coadministration of HMG-CoA reductase inhibitors (eg, lovastatin or simvastatin); coadministration with cisapride can cause cardiac rhythm abnormalities and death May increase digoxin levels; coadministration may increase plasma levels of midazolam or triazolam; phenytoin and rifampin may reduce itraconazole levels (phenytoin metabolism may be altered) |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Monitor hepatic enzyme tests in pre-existing hepatic function abnormalities; absorption is impaired by low stomach acidity and enhanced when administered with an acidic beverage (eg, cola) |
| Drug Name | Potassium iodide (SSKI, Pima) |
|---|---|
| Description | Inhibits thyroid hormone secretion. Third DOC for cutaneous disease. Not effective for systemic disease. Contains 8 mg of iodide per drop. May be mixed with juice or water for intake. |
| Adult Dose | Saturated solution containing approximately 142 g potassium iodide in 100 mL water: 5 gtt tid and titrate up to tolerance, not to exceed 30 gtt tid |
| Pediatric Dose | Administer as in adults |
| Contraindications | Documented hypersensitivity; pulmonary edema, bronchitis, tuberculosis, and hyperkalemia |
| Interactions | Coadministration with lithium and other antithyroid drugs may potentiate hypothyroid and goitrogenic effects; concurrent use with potassium-containing or potassium-sparing medications and ACE inhibitors may result in hyperkalemia and cardiac arrhythmias or cardiac arrest |
| Pregnancy | D - Unsafe in pregnancy |
| Precautions | Prolonged use of iodides can lead to hypothyroidism; caution in patients with Addison disease, cardiac disease, hyperthyroidism, myotonia congenita, tuberculosis, acute bronchitis, or renal function impairment |
| Drug Name | Fluconazole (Diflucan) |
|---|---|
| Description | Synthetic oral antifungal (broad-spectrum bistriazole) that selectively inhibits fungal cytochrome P-450 and sterol C-14 alpha-demethylation. Fourth DOC for systemic disease, modestly effective and thus reserved for itraconazole-intolerant patients. |
| Adult Dose | 400 mg PO qd for lymphocutaneous sporotrichosis or disseminated sporotrichosis |
| Pediatric Dose | 3-6 mg/kg PO qd for 14-28 d or 6-12 mg/kg qd depending on severity of infection |
| Contraindications | Documented hypersensitivity |
| Interactions | Levels may increase with hydrochlorothiazide; fluconazole levels may decrease with chronic coadministration of rifampin; coadministration of fluconazole may decrease phenytoin clearance; may increase concentrations of theophylline, tolbutamide, glyburide, and glipizide; effects of anticoagulants may increase with fluconazole coadministration; increases in cyclosporine concentrations may occur when administered concurrently |
| Pregnancy | C - Safety for use during pregnancy has not been established. |
| Precautions | Monitor closely if rashes develop and discontinue drug if lesions progress; may cause clinical hepatitis, cholestasis, and fulminant hepatic failure (including death) with underlying medical conditions such as AIDS or a malignancy and while taking multiple concomitant medications; not recommended in breastfeeding |
| Drug Name | Terbinafine (Lamisil) |
|---|---|
| Description | Synthetic allylamine hypothesized to act by inhibiting squalene epoxidase, thus blocking synthesis of ergosterol, a vital component of fungal cell membranes. An alternative DOC for cutaneous disease, with promise for systemic disease. |
| Adult Dose | 250-500 mg PO bid |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity |
| Interactions | Inhibitor of CYP450 2D6 isozyme; carefully monitor with coadministration of drugs predominantly metabolized by isozyme (TCAs, SSRIs, beta-blockers, and type B MAOIs); clearance is increased 100% by rifampin and decreased 33% by cimetidine |
| Pregnancy | B - Usually safe but benefits must outweigh the risks. |
| Precautions | Not recommended for patients with liver disease; hepatotoxicity may occur in patients with and without history of liver disease (pretreatment serum transaminase levels [AST, ALT] recommended); patients should report symptoms of persistent nausea, anorexia, fatigue, vomiting, right upper abdominal pain or jaundice, dark urine, or pale stools; not recommended in patients with renal impairment; may exacerbate or precipitate lupus erythematous; isolated cases of several neutropenia reported |
| Media file 1: Close-up of an ulcerated nodule reveals the satellite lesions characteristic of lymphangitic (sporotrichoid) spread. | |
 | View Full Size Image | Media type: Photo |
Article Last Updated: Feb 7, 2007
