Sporotrichosis is a chronic fungal lesion of the body with typical skin manifestations. Isolated pulmonary, osteoarticular and generalized (involving all organs and systems) variants of the disease may be observed. Usually the pathology is accompanied by rashes on the skin and mucous membranes, fever of varying severity. Diagnostics involves the detection of fungus using laboratory techniques, X-ray examinations. Treatment is prolonged with the use of etiotropic antifungal agents and iodine preparations, in some cases – surgical aids, as well as local and symptomatic therapy.
Sporotrichosis (Schenck’s disease, rhinocladiosis) belongs to the group of deep mycoses. The disease was first described in 1898 by an American medical student Schenck, the causative agent was identified in 1900 by scientists from the USA Perkins and Hectoen. Fungi are ubiquitous, but most cases of pathology are registered in tropical countries (especially in Latin America). It is believed that the most vulnerable categories are young men, children, pregnant women, agricultural workers, florists, gardeners, HIV-infected persons, patients taking immunosuppressants, suffering from diabetes mellitus, malignant neoplasms and alcoholism.
The causative agents of infection are fungi of the genus Sporothrix. The most common causes of sporotrichosis are the species Sporothrix schenckii and S. brasiliensis. Microorganisms live inside plants, in a state of spores they persist in moss and soil, under the bark of trees, in fallen foliage. Transmission of infection is carried out by contact with trauma to the skin and mucous membranes by a mechanical object or an animal. Cases of infection by contact with cats, horses, rats, armadillos, snakes, birds and some species of fish have been described. An aerogenic mechanism of disease transmission and possibly transmissible (mosquitoes) is allowed. However, the main method of penetration of fungi into the human body is considered to be a violation of the integrity of the skin when working with plants, especially those with thorns, as well as earth and moss.
The pathogenesis of mycosis has not been studied enough. The pathogen penetrates into the layers of the skin or mucous membranes during traumatic contact (scratch, puncture). The components of the fungal cell wall have receptors for immunocompetent T helper cells of the first order, however, the protein components of the receptors increase the adhesion of sporotrichia to the epithelium, aggravating the invasion. Inflammatory processes occur not only in the skin, but also in the lymph nodes, with the flow of lymph sporotrichia spread throughout the body and enter the circulatory system, resulting in contamination of internal organs.
Granulomas can form in any organs and tissues, most often joints, bones, brain and lungs suffer. Pathohistologically, signs of diffuse chronic granulomatous dermatitis with multiple central abscesses, foci of acanthosis and hyperkeratosis, intraepidermal microabscesses are revealed. Neutrophils and eosinophils predominate in the center of the granuloma, then a layer of mononuclears is found, the outer region consists of plasmocytes and lymphocytes.
The clinical course of sporotrichosis is usually subacute or chronic. The systematization of pathology is based on the degree of depth of fungal invasion into organs and tissues, while up to 80% of cases of mycosis occur locally, without spreading beyond the primary focus. The following forms of fungal lesions are distinguished:
- Skin. Inflammation is detected at the site of the introduction of the pathogen. In children, the focus is often located on the face, in adults – on the hand or forearm. In most cases, regional lymph nodes are involved in the process, the phenomena of lymphangitis and lymphadenitis are detected.
- Bone-articular. There is a clinic of chronic unilateral arthritis involving mainly large joints (ankle, knee, elbow, wrist). Lesions of small joints are less common. Deformations form over time.
- Pulmonary. Aggressive introduction of the pathogen by airborne droplets or hematogenically disseminated pathway leads to lung inflammation with rapid development of respiratory failure and hemoptysis.
- Disseminated. When the pathogen is found in the systemic bloodstream, a widespread rash appears on the skin, numerous foci of fungal reproduction in the internal organs are formed, there is an increasing insufficiency of the functions of internal organs. In the absence of adequate treatment, a fatal outcome occurs.
The incubation period ranges from 3 days to 12 weeks, usually 60-90 days. At the site of penetration of the fungus, mainly on the distal extremities, fingers and toes, a painless seal appears, not soldered to the skin. Usually this process is not accompanied by fever. Over time, the primary focus becomes hard, the skin above it turns red, touching causes unpleasant sensations. In the future, a fistula with a serous-purulent discharge is formed.
The penetration of the pathogen into the lymphatic system leads to an increase and inflammation of the lymph nodes, which become painful, hot, and noticeably change in volume. Typical symptoms of lymphadenitis are fever up to 38-39 ° C, body aches, weakness. When the joints are involved, pain during movement, swelling and local hyperemia appear. The patient spares the limb. The temperature reactions of the body are variable.
Sporotrichous lung lesions are considered prognostically unfavorable. There is severe chills, fever over 39 ° C, cough with mucopurulent sputum, chest pain with coughing jerks, progressive increase in respiratory failure, cyanosis of the skin of the wings of the nose, legs and hands. Septic condition in sporotrichosis is manifested by a rapid increase in fever, impaired kidney, liver, heart, lungs, brain and other organs, loss of consciousness, convulsions.
Most often, immunocompetent individuals have cosmetic defects – scars on the skin, sometimes on the mucous membranes. During the active process, there is a high probability of secondary infection with the development of purulent inflammation of the skin and subcutaneous tissue (usually streptococcal or staphylococcal nature). The long-term consequences of the transferred osteoarticular sporotrichosis may be arthritis with joint deformity and disability of the patient. Isolated cases of lung fibrosis with the occurrence of chronic respiratory failure are described.
The diagnosis of sporotrichosis is verified by an infectious disease doctor. Most often, the doctor needs the advice of a dermatovenerologist, depending on the existing symptoms (lesions of the osteoarticular apparatus, lungs, etc.), examinations by a pulmonologist, surgeon and other specialists may be prescribed. Diagnostic search is carried out using the following clinical, laboratory and instrumental methods:
- Physical examination. During the examination, the severity of the patient’s condition is assessed. The lesion in the cutaneous form of sporotrichosis looks like a papulonodular focus with a tendency to ulceration, often with a fistulous course and separable. Regional lymph nodes are enlarged, sensitive, painful on palpation. The articular form is usually manifested by monoarthritis. Other organ lesions are nonspecific in nature.
- Laboratory tests. Blood and urine tests for sporotrichosis do not have pathognomonic signs. Biochemical parameters change in proportion to organ failure. During histological examination of the affected tissues, asteroid corpuscles or the Splendor-Hoppley phenomenon can be determined. Synovial fluid analysis reveals a high content of polymorphonuclear leukocytes and protein, low glucose levels.
- Identification of infectious agents. The main method of detecting fungus in the body is PCR of biological fluids and body tissues. Microscopy of biopsies, sputum and separated fistulas, sowing on nutrient media is mandatory. A skin allergy test with sporotrichin is used only to a limited extent. Serological studies (ELISA) are mainly used to diagnose generalized infection and relapses.
- Radiation diagnostics. Сhest x-ray in the pulmonary form indicates damage to the upper lobes of the lungs in the form of infiltration, fibrosis, and sometimes decay cavities. On radiographs of joints with a bone-articular form, fistulous passages and signs of osteoporosis are visualized. Ultrasound of soft tissues and lymph nodes is prescribed to detect inflammatory changes.
Differential diagnosis is carried out with infectious diseases. Cutaneous leishmaniasis is a painful ulcer on the background of darkened skin, when ulcers form on the mucous membranes (especially the nose), cartilage is destroyed and the face is disfigured. With cat scratch disease, the primary affect disappears without a trace, leaving no scars. Nocardiosis mainly affects the respiratory system, manifested by pleuropneumonia. Maduromycosis is characterized by the presence of indurative edema, tuberosity, multiple nodes and fistulas in the area of one foot. In addition, sporotrichosis is distinguished with syphilitic chancre, pink acne and some other diseases with similar skin manifestations.
Treatment of patients with cutaneous form can be carried out on an outpatient basis, patients with other types of fungal invasion are usually hospitalized. Bed rest is indicated for fever and severe arthritic pain syndrome. Orthoses, bandages and elastic bandaging are used to ensure rest of the joint. The diet includes nutritious, but light meals with the obligatory use of a sufficient amount of liquid. Local treatment involves the treatment of skin affects with antiseptic solutions and iodine, in order to avoid the ingress of secondary bacterial flora, it is recommended to apply a clean sterile dressing.
Etiotropic therapy of sporotrichosis involves the use of drugs with antifungal activity for oral administration or parenteral administration. The effectiveness of itraconazole, terbinafine, amphotericin B and potassium iodide has been proven. According to the indications, invasive manipulations are carried out: cryosurgery with liquid nitrogen, electrosurgical interventions, surgical excision of tissues. Symptomatic treatment, taking into account the existing manifestations, includes painkillers, antipyretics and antitussives, supportive oxygen therapy. After recovery, a supportive course of antifungal drugs lasting 1-3 months is usually prescribed.
Prognosis and prevention
The prognosis for uncomplicated sporotrichosis is favorable, mortality in the disseminated form reaches 30%. The likelihood of developing severe variants of the disease increases in patients with HIV infection, especially in the AIDS stage, other patients with severe immunity deficiency and alcohol abusers. Skin manifestations disappear after 2-3 months, systemic forms require treatment for six months or more.
Specific prevention (vaccine) has not been developed, new drugs are being tested. The importance of finding preventive remedies is due to the emergence of resistant types of fungus. Non-specific measures to combat sporotrichosis include the use of gloves and protective clothing, the prevention of injuries during work with soil and plants, and the care of pets. Corpses of sick animals are recommended to be cremated.