Actinomycetoma: Symptoms, Diagnosis & Treatment

Introduction:

The latter form of mycetoma, called actinomycetoma, is a chronic subcutaneous infection caused by branching aerobic actinomycetes. It presents as firm tumefaction of the affected site, abscesses, nodules, and sinuses that drain a seropurulent exudate containing filamenting granules. It is an endemic disease in tropical, subtropical, and temperate regions. The infection mainly occurs in agricultural workers and is known to be the most neglected disease. Actinomycetoma is commonly found in soil and water.

What Do You Mean By Actinomycetoma?

Actinomycetoma is filamentous aerobic bacteria that causes mycetoma, a chronic granulomatous infection determined by firm swellings and the presence of nodules, scars, abscesses, and fistulae that drain serous or purulent material containing the etiological agent. Mycetoma is caused by fungi- called eumycetoma, and bacteria- called actinomycetoma.

The most commonly affected sites are the lower limbs, arms, and trunk. Actinomycetoma is aggressive with rapid spreading and has a greater tendency to be extra pedal than eumycetoma.

Invasive infectious agents cause the disease through minor trauma in susceptible individuals. The most common agents are Nocardia brasiliensis, Actinomadura madurai, and Streptomyces somaliensis. 60 percent of mycetoma is caused by actinomycetoma worldwide, predominantly in males. It frequently occurs in farm workers due to higher exposure to minor skin trauma from acacia thorns and splinters in the soil. The specific causative agents vary based on geography and climate. Actinomycetoma is more hostile than eumycetoma and spreads rapidly.

The World Health Organization (WHO) has described actinomycetoma as the most neglected disease, which led to more research to identify the etiology and disease knowledge.

What Are The Symptoms Of Actinomycetoma Infection?

Symptoms include–

• Firm, painless masses under the skin. It develops mainly on foot but also can occur anywhere on the body.

• They start as small masses, but over time they can grow larger, developing oozing sores and resulting in a deformed limb.

• Long-term mycetoma, in due course, destroy the underlying muscle and bone. Improper treatment can cause deformity or disability.

What Is The Risk And Prevention Of Actinomycetoma Infection?

• Actinomycetoma is more common in males than females and is generally seen in South and Central America and some Asian countries. It affects people of all ages, mainly agricultural workers such as farmers and livestock herders.

• Wearing shoes might prevent injuries that lead to mycetoma. This is because they are found in soil and water, and wearing shoes protects the feet while walking and working in soil and water.

• Early detection reduces disabilities caused by mycetoma and heals the disease.

How Is The Disease Transmitted?

The bacteria or fungi causing mycetoma usually live in soil and water. These microorganisms enter the body through wounds or minor injuries like a thorn prick. The infection can develop in some people, and in a few, it may not develop due to acquired immunity. The disease does not spread from person to person. Agriculture workers are commonly affected.

What Is The Diagnosis Of Actinomycetoma Infection?

Diagnosis includes

• History And Clinical Examination: The physician will check for symptoms such as tumefaction, increased volume, and a firm deformity of the affected area with the presence of nodules, scar tissue, abscesses, fistula, and purulent exudate-containing a and ask for medical history.

• Laboratory Tests: Direct microscopy examination of pus with 10 percent KOH or saline reveals granules' presence.

  • The size, form, and color, along with or without clubs or pseudo clubs, help identify the causative agent.

  • Nocardia species are small, reniform granules with club structures in the periphery.

  • A. Madurai appears as yellowish granules that can be seen through the naked eye. However, direct microscopic examination reveals a periphery zone of pseudobulbs that is different from those seen in Norcardia species.

  • Isolation of actinomycetes is achieved by the culture of pus or tissue samples using sabouraud, mycobiota, or blood agar media. Colonies grow after seven to ten days of incubation at 35 to 37 degrees Celsius. These colonies appear as folded, irregular surfaces whose color varies depending on the species. Nocardia- white, chalky, or orange. Madurai- waxy yellow-white or pink, S. somaliensis- yellow-white or bluish colonies.

  • Biochemical tests such as casein hydrolysis, gelatin liquefaction, and decomposition of substrates, such as hypoxanthine, tyrosine, xanthin, and adenine, are used to identify the microorganisms.

  • Mycolic acid analysis of the cell wall is used to determine Nocardia and related genera containing mycolic acids.

  • Actinomycete can be differentiated from eumycetoma based on the width of the filament. In addition, the presence of cysts and chlamydospores of several microns in diameter also helps distinguish actinomycetes from eumycetoma.

• Imaging Tests: This includes radiographs, tomography, ultrasonography, and magnetic resonance imaging that helps delimit the extension of the lesions in bone, organs, and neighboring tissues.

What Is The Differential Diagnosis Of Actinomycetoma Infection?

The differential diagnosis includes

• Sporotrichosis.

• Tuberculosis.

• Osteomyelitis.

• Coccidioidomycosis.

• Phaeohyphomycosis.

• Botryomycosis.

• Amelanotic melanoma.

What Is The Treatment And Management Of Actinomycetoma Infection?

In most cases, pathogenic exposure to actinomycetoma can result in natural immune clearance, but the infection can develop in a few. Adaptive immunity is inducible, specific, transferable, and has a memory representing a hallmark of acquired or adaptive immunity.

Treatment Involves:

• Earlier, Sulfanilamide and Sulfadiazine were used. Welsh regimen was the common treatment, a combination of Trimethoprim or Sulfamethoxazole and Amikacin with a 90 percent cure.

• Other drugs such as Isoniazid, Streptomycin, Rifampin, and Minocycline, are effective.

• Trimethoprim-sulfamethoxazole became the gold standard for actinomycetoma treatment.

• In severe actinomycetoma cases, antimicrobials such as imipenem and meropenem are used. They can be given in association with an aminoglycoside for better efficacy.

• Surgery is not needed for actinomycetoma infection.

Conclusion:

Actinomycetoma is a bacteria that causes mycetoma infection of the feet. It is a chronic disease that can cause deformity of the affected limb. In most cases, it heals on its own, and in some cases, it damages the underlying organ, bone, or neighboring tissue. The infection is seen in men more than women and occurs commonly in agricultural or farm workers as the bacteria is found in soil and water. The actinomycetoma infection is painless and appears as masses or nodules filled with pus. The diagnosis involves a physical examination and microscopic examination of ous or abscess drainage. It is treated using antibiotics, and surgery is not required. Wearing shoes can help in the prevention of infection.