Mycetoma usually progresses slowly, initially appearing as painless lumps or bumps under the skin. This is followed by infection that forms tiny granulomas containing fungal spores, which then swell and deform body parts, mostly in the hands, feet, back and buttocks. Later, chronic infection occurs and mycetoma spreads to other areas of the skin, deeper tissues and even bone, leading to destruction, deformity and loss of function of that tissue.
Continued Part 1
To date, more than 50 Nocardia species have been identified using phenotypic and molecular methods. The Nocardia asteroidescomplex is the major species, associated with various clinical disorders in humans and animals, including birds. The Nocardia asteroides omplex is classified into types I, II, III, IV, and V. Type III is called Nocardia nova and type V is Nocardia Farcinia.
Recently, Nocardia cyriacigeorgica was differentiated from Nocardia asteroidesand is now considered an emerging pathogen in the United States. Hamid et al. isolated Nocardia africana, a novel pathogen, from patients with pulmonary infections.
The recorded history of nocardiosis dates back to 1888 when Edmond Nocard first described an aerobic actinomycete causing disease in cattle with bovine farcy on the island of Guadeloupe, West Indies. However, the first case of the disease in humans was reported by Eppinger in 1890 in a 52‐year‐old glassblower. Pal is credited with being the first to explain the pathogenic role of Nocardia asteroides in corneal ulcers in cattle from India. On the other hand, Nocardia asteroides does not form granulomas in tissues; however, other species such as Nocardia caviae, Nocardia mexicana và Nocardia brasiliensis and Nocardia brasiliensis are characterized by the presence of granulomas. Cattle and dogs are more commonly affected than other animals.
Bovine mastitis is the most common clinical manifestation of nocardiosis in livestock. In previous studies conducted in Brazil Nocardia asteroides andNocardia brasiliensis were identified as the most common causative agents of bovine mastitis.
The disease in dogs presents with a wide range of clinical manifestations. The cutaneous or subcutaneous form, similar to human mycetoma, which presents with purulent discharge resembling tomato soup, is of particular concern. Nocardia otitidiscaviarum was isolated from eight cases of cutaneous‐subcutaneous lesions and one case of pneumonia in dogs in 2008 in Brazil.
Recently, Hattori et al. isolated Nocardia. africana from a case of mycetoma in a cat. Nocardia brasiliensis is the most common causative agent of mycetoma. Recently, Rodriguez‐Nava et al. reported Nocardia mexicana, a novel causative agent of mycetoma in humans.
CLINICAL FEATURES OF MYCETOMA
Mycetoma usually progresses slowly, initially appearing as painless lumps or bumps under the skin. This is followed by infections that form tiny granulomas containing fungal spores, which then swell and deform body parts, mostly in the hands, feet, back and buttocks. Chronic infection then develops and mycetoma spreads to other areas of the skin, deeper tissues and even bones, leading to destruction, deformity and loss of function of that tissue. Bacterial infections are also common, with symptoms often gradually increasing pain, loss of ability and sepsis which can be fatal if not treated promptly. Many people with mycetoma become depressed and require psychiatric support.
Clinical characteristics of patients with mycetoma tend to be late in diagnosis and treatment and are affected by many factors. The disease is often initially painless and other factors that may delay diagnosis and treatment include poor socioeconomic status and low education, financial resources and distance from local health facilities.
The disease is usually characterized by a triad: Painless swelling under the skin, forming tunnels and producing pus or pus and serum containing granules. These granules have different colors and sizes due to infection with many different agents. Their color can be black, white, yellow or red and give evidence of the cause. The subcutaneous masses often spread to deep skin areas and structures, leading to structural destruction, causing disfigurement and loss of function, sometimes leading to death. Mycetoma often affects the feet and hands (accounting for more than 80% of mycetoma cases).
Some special cases of mycetoma appear on the head, neck, chest, abdominal wall, perineum, buttocks and should be noted to be easily confused with other dermatological lesions.
DIAGNOSIS OF MYCETOMA
Mycetoma can be identified by direct examination of fluid and secretions containing fungal spores, and by microscopy of specimens, however, additional tests are required for a definitive diagnosis. Currently, there is no simple test used in rural areas for the fastest diagnosis, so patients are required to go to medical centers or hospitals for diagnosis, including biopsy, x‐rays and ultrasound. The earlier the infection is diagnosed, the higher the chance of cure, so early, fastest and earliest diagnosis is necessary.
MYCETOMA TREATMENT
In general, actinomycetoma responds well to combination therapy, and the combination should be designed to avoid the development of resistance and eliminate the disease earlier. Currently, the recommended combination therapy is co‐trimoxazole (980 mg twice daily) and amoxicillin‐clavulanic acid (1 gram/day). Alternative therapy is amikacin sulphate (15 mg/kg/day) and co‐trimoxazole (980 mg twice daily) given in 5‐week courses. Treatment may last more than a year and cure rates range from 70‐80%.
Treatment of mycosis fungoides is not long‐term, and the recurrence rate is high. It is necessary to use combined antifungal therapy (currently using itraconazole 400 mg/day) and surgical removal of the infected area. Surgery to enlarge the lesion, repeated excision until amputation or limb amputation. Surgery is performed when local lesions are resistant to medical therapy and can save the patient’s life when the disease progresses complicatedly, or there is secondary infection, sepsis, bone masses, and the patient’s general condition is poor.
Some data suggest that voriconazole may be a better choice for some fungi, notably Medicopsis (Pyrenochaeta) romeroi. However, clinical practice has shown only 25‐35% overall efficacy, but with good patient compliance over 12 months, efficacy can be as high as 80%, with side effects being noted.
The drugs are often very expensive for the patient and are not always available in the areas where the patient is diagnosed. Also, for bacterial mycosis the cure rate is >90% with combination antibiotic therapy.
Although hosts are constantly exposed to pathogens, fungi are relatively uncommon causes of disease in healthy humans and animals. However, the number of fungal diseases in animals has increased significantly over the past two decades, originating from opportunistic and pathogenic fungi.
TRANSMISSION OF MYCETOMA
Mycetoma pathogens are usually transmitted through the environment via contaminated plant debris or from soil into areas of trauma.
For over a century, this pathway has affected specific occupational groups, including agricultural workers and gardeners. On the other hand, the presence of mycetoma in animals suggests that mycetoma is an occupation‐independent disease.
WHO SUPPORTS COUNTRIES WITH ENDANGERED DISEASE
In 2016, the 69th World Health Assembly adopted Resolution WHA69.21 on access to and control of mycetoma. The resolution called on WHO to support countries to improve disease surveillance and to promote research to develop better tools for the diagnosis and treatment of mycetoma. In response, in 2017, WHO sent a questionnaire to all countries to collect comprehensive baseline information on the global prevalence of the disease. The results were published in the Weekly Epidemiological Record , N° 33, 17 August 2018, pp. 423–428 and a version of the full survey results on mycetoma can be accessed at https://iris.who.int/bitstream/handle/10665/274019/
To build national capacity on clinical and public health aspects of mycetoma, the Government of Sudan and WHO organized a first training workshop on mycetoma at the WHO Collaborating Centre on Mycetoma at the University of Khartoum in 2019.
As with other neglected tropical skin diseases (skin‐NTDs), the primary goal of control is to minimize the physical disability and severe socioeconomic impact of mycetoma. Some key points of the Control Strategy include:
- Increase community awareness of the disease and how to detect it early
- Medical staff training
- Access to diagnosis, treatment and orthopedics
- Good disease surveillance.
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