Actinomycetoma

Actinomycetoma is a chronic, progressively destructive morbid inflammatory disease usually of the foot but any part of the body can be affected. Infection is most probably acquired by traumatic inoculation of certain ‎bacteria into the subcutaneous tissue. It was described in the modern literature in 1694 but was first reported in the mid-19th century in the Indian town of Madura, and hence was initially called Madura foot.

Actinomycetoma commonly affects young adults, particularly males aged between 20 and 40 years, mostly in developing countries. People of low socioeconomic status and manual workers such as agriculturalists, laborers and herdsmen are the worst affected.

It has numerous adverse medical, health and socioeconomic impacts on patients, communities and health authorities.

As actinomycetoma is a badly neglected disease, accurate data on its incidence and prevalence are not available.

Pathogenesis

v  Bacteria causing actinomycetoma have mycolic acids in their cytoplasmic membrane as virulence factor, & are considered to have low pathogenic potential however and most of them live as saprophytes in soil.

v  Actinomycetoma occurs most often in people who work in rural areas, usually in farmers, hunter-gatherer populations, and field laborers where they are exposed to acacia trees or cactus thorns that contain the etiologic agents that normally live as saprophytes.

v  The disease can also been found in people who work in the city in various occupations, in victims of road accidents who have incurred a traumatic inoculation of the agent, and in travelers to tropical endemic areas

v  The infection is acquired by direct inoculation via skin. Actinomycetoma are a disease of poverty & young male individuals living in endemic regions engaged in agricultural activities have the highest incidence of actinomycetoma.

v  Feets are commonly affected followed by hands, legs and knee joints. In highly endemic areas other body parts may affect.

v  Actinomycetoma is a chronic granulomatous infection characterized by the triad of tumefaction (swelling), draining sinuses and presence of grains. Grains, also known as sclerotia,   are aggregates of the bacterial filaments,   sometimes embedded in tough, cement-like material.

v  The morphological characteristics and color of the grains provides clues about the species of the agents.

v  Infection begins in the subcutaneous tissue after being implanted there and takes a slow progressive course.

v  The subcutaneous nodule increases in size and secondary nodules might evolve as well. The nodules might suppurate and drain through multiple sinus tracts, and these sinuses can close transiently after discharge during the active phase of the disease.

v  Fresh adjacent sinuses might open whereas some of the old ones might heal completely.

v  The nodules are connected to each other through deep sterile abscesses, and to the skin surface.

v  The lesions are painless except in the end stage where bone invasion may cause pain.

v  As the actinomycetoma granuloma increases in size, the skin may become smooth and shiny, and areas of hypopigmentation or hyperpigmentation can occur.

v  Incubation period can vary from several months to years.

Diagnosis of actinomycetoma

Physical examination

The lesion is also becoming painful. Physical examination of the foot shows hyperpigmented skin overlying a semi-solid mass, 8cm in diameter, attached to the skin lateral and plantar of the midfoot. The mass is painful on palpation, and there are several small ulcers but with no drainage at this time.

Laboratory diagnosis

The diagnosis of mycetoma depends on identifying grains. These are obtained using a needle and syringe to extract material from a soft part of the lesion under the skin or by collecting pus. Occasionally a skin biopsy is necessary, which shows characteristic histopathological features of actinomycetoma and may reveal the organisms.

The pathology report was positive for dermal sulfur granules compatible with actinomycosis.

The colour of the grains may suggest the likely diagnosis;

·         Minute white grains suggest nocardia.

·         Brown or Red grains are due to:

a)      Actinomadura pelletieri (Africa)

b)      Streptomcyes somaliensis (North Africa, Middle East).

·         The most common actinomycetes to cause mycetoma with white/yellow grains are:

a)      Actinomadura madurae (Worldwide)

b)      Nocardia asteroides (Worldwide)

c)       Nocardia brasiliensis (Central America)

Microscopy using potassium hydroxide (KOH) confirms the diagnosis. Actinomycotic grains contain very fine filaments.

Specie	Morphology of grains
Actinomadura madurae	Large (1-5 mm and larger) and multilobulate; peripheral basophilia and central eosinophila or pale staining, filaments grow from the peripheral zone.
Streptomyces somaliensis	Large 0.5-2 mm or more) with dense thin filaments; often stains homogenously; transverse fracture lines.
Nocardia brasiliensis	Small grains (approximately 1 mm); central purple zone; loose clumps of filaments. Gram positive delicate branching filaments breaking up into bacillary and coccal forms; Gram negative amorphous matrix.

Treatment of actinomycetoma

v  Actinomycetoma responds well to treatment with appropriate antibiotics but they are required for months or years. The sinuses dry up, swelling and tenderness improves and the grains disappear. Deformity may persist.

v  In general, actinomycetoma is amenable to medical treatment with antibiotics and other chemotherapeutic agents. Combined drug therapy is always perfect in contrast to a single drug to avoid drug resistance and for disease eradication. In the past, the treatment of actinomycetoma was by combination of streptomycin sulphate in a dose of 14 mg/kg daily for one month then on alternate days and 4,4'-Diaminodiphenyl sulphone (Dapsone) in a dose of 1.5 mg/kg twice daily till cure. The cure rate varied between 60 and 90%. This treatment regime needs a long duration to achieve cure and has many side effects.

v  For patients who did not respond to treatment or those who had persistent side effects to dapsone, the dapsone is replaced by Co-tri-moxazole in a dose of 1.5 mg/kg twice daily. Certain actinomycetes such as Actinomadura pelletierii have good response to this combination and it was used as the first line treatment. Other single or combination treatment is used:

·         Rifampin,

·         Sulfadoxine

·         Pyrimethamine (Fansidar)

·         Sulphonomides

v  Above all are second line of treatment for actinomycetoma.

v  Patients who did not respond to the first line treatment or who developed serious drug side effects. However, these drugs take a long time to achieve cure, the mean duration was around one year and the recurrence rate was high. They have many side-effects and some of these were serious such as Stephen Johnson syndrome.

v  In actinomycetoma, combined medical and surgical treatments are beneficial. This regime facilitates surgery, accelerates healing and reduces the chance of relapse, however a good number of patients respond to medical treatment alone.

v  Cure is possible, though a prolonged period of treatment is needed.

v  Recurrence is more common after an incomplete or irregular course of medical treatment. With drug incompliance, there is a good chance for the organism to develop drug resistance.

Prevention

v  Use closed foot wears.

v  Thoroughly clean penetrating wounds; especially in endemic areas.

v  Avoid carrying sticks and thorny branches that have had contact with soil, especially if contaminated with cattle dung.

v  Actinomycetoma is a rare condition that is not contagious.