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2012 Case #4 | ![]() |
Diagnosis: Sporotrichosis due to Sporothrix schenkii. |
![]() The differential diagnosis of nodular or ulcerated lesions in Perú with or without lymphocutaneous spread includes leishmaniasis, sporotrichosis, atypical mycobacteria, and nocardiosis. Sporotrichosis is always an important consideration in areas such as Perú even where leishmaniasis is much more common. In normal hosts, linear sporotrichoid lesions on an extremity would be the most common presentation of sporotrichosis [see Gorgas Case 2008 #1]. In normal hosts, extracutaneous manifestations of sporotrichosis include osteoarticular, meningeal, and pulmonary sporotrichosis. These are usually seen in immunocompromised hosts and in alcoholics. In the last 2 decades a systemic presentation restricted almost exclusively to HIV patients has been described [see Gorgas Case 2011 #2] [Curr Fungal Infect Rep. 2011;5(1):42-8]. Environmental reservoirs for S. schenkii include sphagnum moss (including wood or plants contaminated by moss), decaying vegetation, hay, soil and masonry. Outdoor work including farming, construction, gardening, and having a cat are risk factors [Clin Infect Dis. 2004;38(4):529-35 and Clin Infect Dis. 2003;36(1):34-9]. Acquisition is generally by local inoculation. Sporotrichosis is distributed worldwide but most cases are reported from the Americas and Japan. Most cases are sporadic or occur in self-limited clusters due to some point source exposure. The area around Abancay, Perú (not where this patient lives) has recently been, perhaps uniquely, identified as an area where sporotrichosis is not only entrenched but is hyperendemic with annual incidence rates of up to 60 per 100,000 population [Clin Infect Dis. 2003;36(1):34-9 and Clin Infect Dis. 2000;30(1):65-70]. Guidelines for treatment of sporotrichosis have been released by the Infectious Diseases Society of America [Clin Infect Dis. 2007;45(10):1255-65] and are partly based on work from our Institute. The treatment of choice for lymphocutaneous sporotrichosis is itraconazole, and in severe extracutaneous or disseminated disease amphotericin B can be used. Terbinafine 500-1000 mg po bid has been shown to be effective therapy [Mycoses 2004;47(1-2):62-8]. Posaconazole is the only newer azole to have good in vitro activity against S. schenckii. Fluconazole at higher doses (400-800 mg daily) has demonstrated some activity for lymphocutaneous sporotrichosis, but voriconazole, ravuconazole and the echinocandins are ineffective against S. schenckii though some are active against other Sporothrix species. In the reality of poor countries, many patients cannot afford itraconazole or terbinafine. The older but still effective mode of therapy with a saturated solution of potassium iodide (SSKI) is still widely used in practice. SSKI and its clinical use has been reviewed [J Am Acad Dermatol. 2000;43(4):691-7] and we have previously demonstrated the utility of once daily dosing in order to increase compliance [Pediatr Infect Dis J. 1996;15(4):352-4]. The mechanism of action is unknown. SSKI can also be used for entomophthoramycosis caused by Basidiobolus and Conidiobolus. In dermatologic practice SSKI can be used for erythema nodosum, nodular vasculitis, erythema multiforme, and Sweet’s disease. The main adverse effects are gastrointestinal (nausea) and the SSKI can be added to larger volumes of water, juice, or milk for administration. Care must be taken to avoid potassium or iodide toxicity in those patients on ACE inhibitors or potassium sparing diuretics, those with renal disease, and in those on medications or with conditions making them unable to autoregulate thyroid hormone production. In areas with high rates of iodine deficiency, such as the Andean highlands, the use of this solution can trigger hyperthyroidism (Jod-Basedow disease). This patient was treated with SSKI. The standard recommendation is a 100% solution that will give 1g/ml); starting with 1ml per day and increasing to 1ml tid in three days to progressively reach 5g/ml (~7ml). We have used a higher dose on some patients, 2.5 ml tid of 100% SSKI [Curr Fungal Infect Rep. 2011;5(1):42-8]. The plan is for a 3-month course of treatment. The patient is complaining of a metallic taste and epigastric pain. Acknowledgements: We thank Beatriz Bustamante, Rosario Velando, Susana Araníbar and Susana Rigoletto from the Mycology Laboratory of our Institute for their assistance, and UAB Professor Peter Pappas for reviewing the text.
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