A 40-year-old otherwise healthy gardener presents with several subcutaneous nodules on his right hand, where he had cut himself on rose thorns. Physical exam reveals several erythematous fluctuant lesions. Which of the following organisms is most likely responsible for his condition?

Whenever you see a question on a gardener who works with roses, think "Sporothrix schenckii." This organism is responsible for "rose gardener's disease," known technically as sporotrichosis. The organism enters through skin breaks in the fingers or hands, causing a chancre, papule, or subcutaneous nodule with erythema and fluctuance. Ulcerating lesions appear along lymphatic channels, but the lymph nodes are not commonly infected. Potassium iodide is the treatment of choice for the sub cutaneous manifestations. Aspergillus causes pulmonary aspergillosis ; a systemic mycotic infection. There is an allergic type that is caused by a hypersensitivity reaction to the organism and an infectious type that occurs more commonly in the immunocompromised. Hemoptysis is a common symptom. Malassezia, specifically M. furfur, causes tinea versicolor, a superficial mycotic infection. Onchocerca, specifically O. volvulus, causes river blindness. Ref: Ray C.G., Ryan K.J. (2010). Chapter 44. Dermatophytes, Sporothrix, and Other Superficial and Subcutaneous Fungi. In C.G. Ray, K.J. Ryan (Eds), Sherris Medical Microbiology, 5e.