Verticillium species is a filamentous fungus that inhabits decaying vegetation and soil. It is known to cause disease in plants. Four cases of human infections have been reported previously in nontransplant patients. Here, we report the first case of Verticillium species skin infection in a transplant patient who was successfully treated with fluconazole monotherapy.

Key words : Diabetes mellitus, Fluconazole, Human subject

Introduction

Patients who receive solid-organ transplants are prone to have infections with opportunistic pathogens. Verticillium is a fungus rarely associated with human disease.^1-5 Here, we report a case of skin and soft tissue infection in a patient who had received a renal transplant.

Case Report

The patient was a 45-year-old female patient who underwent living-donor related kidney transplant from her son. No induction immunosuppression was used, and maintenance therapy included tacrolimus, mycophenolate mofetil, and prednisolone. She showed excellent graft function, with serum creatinine level of around 60 μg and estimated glomerular filtration rate of > 60 mL/min. No graft rejection was shown. Tacrolimus level was kept between 4 and 6 ng/mL at 3 months after transplant.

Sixteen months after transplant, she presented with an unrelenting skin lesion that had started 12 months after transplant. This lesion had started after minor trauma to the left medial malleolus. The patient was from southern Saudi Arabia where she visited farms after that trauma. The lesion grew gradually in size, with occasional oozing of pus. The patient reported no pain or itching regarding the lesion (Figure 1). The patient denied fever, night sweats, and weight loss. The patient had diabetes mellitus, and her HbA1C was 8.7%. She was on the following medications: tacrolimus (5 mg twice daily), mycophenolate mofetil (750 mg twice daily), single-strength trimethoprim-sulfamethoxazole (1 tablet/day), labetalol (100 mg twice daily), insulin, and ferrous sulfate.

Physical examination of the patient was negative for lymphadenopathy and organomegaly. The left medial malleolus showed a nodule, 1.5 cm in diameter, with shiny smooth purple surface. There was mild surrounding erythema (Figure 1). A puncture on the periphery of the lesion was oozing pus. Swabs from the pus were sent twice for smear tests, with both showing yeast-like organisms. The specimen was sent for culture, which resulted in fungal colony growth 7 days later and which was subsequently identified as Verticillium species 10 days after culture. No other organisms were isolated. A biopsy of the lesion was done, with tissue culture also resulting in Verticillium growth. Tissue histology showed acute and chronic inflammatory changes (Figure 2A), and special stains revealed numerous fungal organisms with spores and hyphae-like elements (Figure 2B).

The patient was started on fluconazole (100 mg daily by mouth). Follow-up 12 days later showed a marked decrease in the lesion size. The lesion completely disappeared 3 weeks after starting treatment. A 3-year follow-up showed no recurrence.

Discussion

Verticillium is a widely distributed filamentous fungus that inhabits decaying vegetation and soil. Verticillium is a major plant pathogen, with 5 known plant pathogenic species: V. longisporum, V. albo-atrum, V. nigrescens, V. tricorpus, and V. dahliae. Verticillium has been linked to cauliflower vascular wilt disease⁶ and to diseases in tomato, cotton, and olive plants.⁷ Verticillium has also been reported to cause disease in fish⁸ and snakes⁹ and is known to be parasitic to other fungi¹⁰ and to insects.

In humans, it is considered to be nonpathogenic. In previous reports, Verticillium spores have been linked with occupational obstructive respiratory symptoms1 and with asthma.² A case of peritonitis due to Verticillium species in a 33-year-old farmer on continuous ambulatory peritoneal dialysis has also been reported.³ Other reports have implicated Verticillium species in stromal keratitis in a 50-year-old immunocompetent man4 and presented a case of soft tissue infection from Verticillium species in a patient with juvenile diabetes mellitus.⁵ Verticillium species has also been reported to cause endop­hthalmitis following cataract surgery.¹¹

Here, we report a patient with Verticillium species infection involving skin and soft tissue who presented with symptoms after living-donor related renal transplant. The infection was confirmed by microbiology and histology and responded well to fluconazole. Rare species of fungal infection should be considered in the differential diagnosis of skin lesions, especially in immunosuppressed patients. Infection from Verticillium species showed response to fluconazole monotherapy in our patient. In 2 of the previously reported patients, along with fluconazole, flucytosine was given in one case and topical amphotericin B in the other (keratitis). Voriconazole has been used to treat endophthalmitis.¹¹ In our patient, fluconazole monotherapy seemed to be effective for the skin infection due to Verticillium species.

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