We report a pediatric case of sporotrichosis with zoonotic transmission of Sporothrix schenckii from a feline to an otherwise healthy 2-year-old girl.
Sporotrichosis typically presents as a subcutaneous mycosis secondary to the dimorphic fungus, Sporothrix schenckii. The classic clinical presentation involves a site of inoculation and evidence of lymphocutaneous spread, typically in the setting of an individual with a history of a thorn prick. There is persistent local infection at the site of inoculation evolving to ulceration. In many cases, proximal lymphatic spread with subcutaneous nodules and overlying erythema may be noted.
Sporotrichosis commonly manifests as a localized cutaneous infection occurring in immunologically normal hosts. This entity occurs in persons with frequent exposure to plant material such as rose bushes, hence commonly being referred to as “rose gardener’s disease.” Sporotrichosis is more prevalent in warmer moist climates. Pulmonary and disseminated infections are less common, though can be devastating. Animal to human transmission is reported but is rare. This infection more commonly affects adults but can be seen in all ages. There have been increasing reports of S schenckii transmission by infected cats, particularly in the Rio de Janeiro region of Brazil. S schenckii tend to be present in large numbers within the nonhealing ulcers of these animals.1
Figure 1A. Edematous ulcerative plaque with overlying pustules on the right wrist.
A 2-year-old girl from central Texas presented to our pediatric dermatology clinic with a 1-month history of a nonhealing wound on the right wrist. She had been treated with a 2-week course of cephalexin and clindamycin without improvement. She was also receiving frequent wound care treatments without improvement. Of note, the patient lived in a rural area with exposure to a variety of outdoor animals. Interestingly, the patient’s mother mentioned that the family had an outdoor cat that had multiple nonhealing ulcers on the face and body for months. The cat was routinely in close contact with the patient, but there was no known history of a cat bite or scratch. The patient was also noted to be helping her mother in their garden over the preceding months but had no known thorn injury. The child’s mother also noted that they had a fish and turtle pond that the child frequently played near. The patient had no history of out of state or international travel. The patient had no history of recurrent infections or immunosuppression.
Figure 1B. Multiple firm erythematous nodules distributed in a linear fashion along the right upper arm.
Upon initial evaluation, physical examination revealed a well-appearing toddler in no acute distress. The patient was afebrile. Examination of the right hand and wrist revealed a rather well-demarcated, erythematous, ulcerative pink plaque with scattered pustules and 2 firm, erythematous, subcutaneous nodules in a linear distribution along the upper right arm (Figures 1A and B). The plaque was tender to palpation. There was no epitrochlear, axillary, or cervical lymphadenopathy noted. The patient did not display any hepatosplenomegaly. There were no other cutaneous findings. Review of systems was otherwise negative. Two punch biopsies from the ulcerated plaque were performed for routine histology and bacterial, fungal, and atypical mycobacterial tissue cultures. Out of concern for an atypical mycobacterial infection, the patient was initially empirically started on oral clarithromycin 15 mg/kg per day divided twice daily. Cat-scratch disease was also considered in the initial clinical differential. Infectious serology workup revealed negative screening for Blastomyces, Histoplasma, Coccidioides, and Cryptococcus. Upon clinic follow up, after approximately 1 week after starting the oral clarithromycin, the ulcerative plaque continued to enlarge and become increasingly painful. New sporotrichoid nodules continued to migrate up the right forearm and upper arm as well.
Article continues on page 2
Histology from the right wrist revealed a lichenoid and granulomatous infiltrate with negative staining for spirochetes, fungi, and atypical mycobacteria (Figures 2A and B). Tissue culture, after approximately 2 weeks, grew S schenckii, which was sensitive to itraconazole, posaconazole, terbinafine, and micafungin. At that time, the patient was switched from clarithromycin to the treatment of choice, oral itraconazole 4 mg/kg twice daily for a 4-month course with resolution of the lesions. The itraconazole was discontinued after the patient’s skin had healed and was not producing any new sporotrichoid nodules for approximately 1 month.
Figure 2A. Biopsy from right wrist revealed epidermal acanthosis and a brisk lichenoid interface lymphocytic infiltrate. There is a dense superficial and deep perivascular lymphohistiocytic infiltrate.
Shortly after the patient’s diagnosis, the family brought their outdoor cat to the veterinarian to evaluate the cat’s nonhealing ulcers (Figure 3). The cat’s skin biopsy showed similar histologic findings to our patient. Routine infectious stains were negative for S schenckii, but linear basophilic bodies were seen in occasional macrophages, with the overall shape and size highly suggestive of Sporothrix. Cultures were not done as the family elected to euthanize the cat.
Figure 2B. Higher power reveals poorly formed dermal histiocytic necrotizing microgranulomata with central neutrophilic infiltrates. Periodic acid–Schiff, Grocott-Gomori methenamine silver-nitrate, acid-fast bacillus, and Wright-Giemsa were negative. Immunohistochemical stains for spirochetes were negative.
Sporotrichosis is an infection that is caused when an individual is exposed to the fungus S schenckii, which is often found in soil and decaying vegetation. Transmission occurs when spores of S schenckii enter the skin directly due to inoculation from penetrating trauma (eg, rose bush thorns) or from bites or scratches from infected animals, such as cats and dogs.2 Individuals most commonly at risk for contracting sporotrichosis are those in close contact with soil, such as gardeners and farmers. This fungus is often found in areas with warmer and temperate climates and is the most common cause of subcutaneous mycosis in humans in Mexico and Latin America.3
Patients with sporotrichosis most commonly present with subcutaneous nodules and ulcers at the inoculation site approximately 3 weeks after infection. The infection can continue to spread along lymphatic vessels and produce linearly arranged sporotrichoid nodules. Immunocompromised patients may also present with pulmonary, bone, joint, and other visceral involvement which is indicative of disseminated disease.4 Our patient had no signs or symptoms of disseminated infection and remained afebrile for the entire treatment course.
Figure 3. Multiple nonhealing ulcers located on the nose and periorbital areas of the patient’s pet cat.
The differential diagnosis for cutaneous sporotrichoid nodules includes cutaneous nocardiosis, sporotrichosis, atypical mycobacterial infection (eg, Mycobacterium marinum), leishmaniasis, as well as staphylococcal and streptococcal infections. In our patient’s case, her exposure to both gardening and a fish pond prompted top consideration of either sporotrichosis or an atypical mycobacterial infection, such as M marinum. The diagnosis of S schenckii is typically made through microscopic examination, and fungal culture of infected tissue. S schenckii grows on Sabouraud glucose agar plates and characteristically forms “cigar-shaped” yeast at 37°C.4 Histopathologic findings typically display abscess formation and a granulomatous tissue response.5 This organism can be difficult to locate on initial skin biopsies, despite using special fungal staining as was performed in this case. M marinum typically inhabits aquatic environments, including fresh, salt, and brackish water. This organism can lead to cutaneous infection from traumatized skin exposed to fish tanks or working in fish markets.6
M marinum is the most common nontuberculous mycobacteriosis to present with sporotrichoid lymphocutaneous spread. This organism may even lead to osteomyelitis, tenosynovitis, septic arthritis, or disseminated infection in immunocompromised patients. Histology may reveal an acute to chronic inflammatory infiltrate to tuberculoid granulomas.7 Like S schenckii, M marinum may be difficult to find on histology, particularly in immunocompetent patients. Tissue cultures are positive in 70% to 80% of cases and grows best at 31°C.8
Zoonotic transmission of sporotrichosis from felines to humans is relatively rare in the United States. More than 4000 cases of feline-transmitted cases have been reported from Brazil since the 1990s outbreak in Rio de Janeiro.9 Particularly in zoonotic cases of sporotrichosis, it is of the utmost importance to identify the source of infection so that timely and appropriate therapy can be initiated, both for the affected patient and the animal. Additionally, the clinician should also request sensitivities to confirm that the most effective antifungal agent is being used. Our patient was successfully treated with oral itraconazole without recurrence of active disease, leaving atrophic scars. The child’s mother continues to closely follow up to ensure that the infection remains cured and there are no signs or symptoms of disseminated disease.
Dr Green is with the division of dermatology in the department of medicine at the University of Austin Dell Medical School in Austin, TX.
Ms Manivannan is with the Texas Tech University Health Sciences Center in El Paso, TX.
Dr Murphey is with the department of pediatrics at the University of Texas at Austin Dell Medical School and affiliated with the Dell Children’s Medical Center in Austin, TX.
Dr Diaz is with the division of dermatology in the department of medicine and the department of pediatrics at the University of Austin Dell Medical School and affiliated with the Dell Children’s Medical Center in Austin, TX.
Disclosure: The authors report no relevant financial relationships.
1. Galhartdo MC, De Oliveira RM, Valle AC, et al. Molecular epidemiology and antifungal susceptibility patterns of Sporothrix schenckii isolates from a cat-transmitted epidemic of sporotrichosis in Rio de Janeiro, Brazil. Med Mycol. 2008;46(2):141-151.
2. Kauffman CA, Hajjeh R, Chapman SW. Practice guidelines for the management of patients with sporotrichosis. Clin Infect Dis. 2000;30(4): 684-687.
3. Werner AH, Werner BE. Sporotrichosis in man and animal. Int J Dermatol. 1994;33(10):692-700.
4. Badley AD, Van Scoy RE, Long-term follow-up of multifocal osteoarticular sporotrichosis treated with itraconazole. Clin Infect Dis.1996;23(2):394-395.
5. Zhang Z, Hou B, Xin Y, Liu X. Protein profiling of the dimorphic pathogenic fungus, Sporothrix schenckii. Mycopathologia. 2012;173(1):1-11.
6. Hautmann G, Lotti T. Atypical mycobacterial infections of the skin. Dermatol Clin. 1994;12(4):657-668.
7. Bolognia JL, Jorizzo JJ, Schaffer JV, et al. Dermatology. 3rd ed. London, England: Elsevier; 2012:1235-1242.
8. Gluckman SJ. Mycobacterium marinum. Clin Dermatol. 1995;13(3):273-276.
9. Pereira SA, Gremiao ID, Kitada AA, Boechat JS, Viana PG, Schubach TM. The epidemiological scenario of feline sporotrichosis in Rio de Janeiro, State of Rio de Janeiro, Brazil. Rev Soc Bras Med Trop. 2014;47(3):392-393.