What are the other Names for this Condition? (Also known as/Synonyms)

• Myositis Purulenta Tropica
• Myositis Tropicans
• Suppurative Myositis

What is Tropical Pyomyositis? (Definition/Background Information)

• Tropical Pyomyositis is a rare but life-threatening bacterial infection that is predominantly observed during childhood and young adulthood. It results in the formation of abscesses within the skeletal muscles from a variety of causative factors
• These include immunocompromised status, malnutrition, other skin infections, and poorly-controlled diabetes. The signs and symptoms of Tropical Pyomyositis may be non-specific and include pain, fever, and formation of multiple abscesses, which can be severe without early detection and prompt treatment
• The management of Tropical Pyomyositis may include surgical drainage of the abscesses along-with aggressive antibiotic therapy. Additionally, undertaking a treatment of the underlying cause, if any present, is important. The prognosis of Tropical Pyomyositis is good with early recognition and appropriate therapy

Who gets Tropical Pyomyositis? (Age and Sex Distribution)

• Tropical Pyomyositis is a rare bacterial infection. The presentation of symptoms may occur at any age, but most cases are reported in children and young adults between 10 to 40 years of age
• Although both genders are affected, the condition occurs at a higher frequency in males (male-female ratio is 3:2)
• The condition is mostly endemic to eastern Uganda. It is more common in the tropics, although the infection is on the rise in temperate climates as well

What are the Risk Factors for Tropical Pyomyositis? (Predisposing Factors)

The risk factors for Tropical Pyomyositis may include the following:

• Children aged 2-5 years, or young adults in the tropical regions have a higher risk
• Immunodeficiency due to various causes such as:
  • HIV infection and AIDS
  • Autoimmune disorders
  • Severe malnutrition
  • Chronic kidney failure
  • Organ transplant
  • Use of immunosuppressants
  • Cancer therapy
  • Liver cirrhosis
• Uncontrolled diabetes
• Strenuous physical activity and exercising
• Injury to muscles
• Skin infections
• Certain parasitic and viral infections
• Infected insect bites
• Injection of illicit drugs
• Certain connective tissue disorders

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Tropical Pyomyositis? (Etiology)

• Tropical Pyomyositis is a mostly bacterial infection of the skeletal muscle, which in a majority of cases is caused by the bacterium Staphylococcus aureus (in over 90% of the cases), typically methicillin-susceptible S. aureus
• The infection results in abscess formation and associated signs and symptoms

Other causative pathogens of Pyomyositis include:

• Candida spp.
• Escherichia coli
• Certain gram negative bacteria
• Group A Streptococci, which accounts for 1-5% of the cases
• Haemophilus spp.
• Klebsiella spp.
• Mycobacterium spp.
• Pneumococcus spp.
• Pseudomonas aeruginosa

What are the Signs and Symptoms of Tropical Pyomyositis?

The signs and symptoms of Tropical Pyomyositis may vary from one individual to another. These may include:

• Presence of a single or multiple abscess
• Pain and tenderness in the affected skeletal muscles
• Any of the body muscles may be affected, such as at the following locations:
  • Abdomen
  • Arm
  • Buttocks
  • Chest
  • Leg and knee joint
  • Paraspinal 

Three distinct stages of Tropical Pyomyositis is recognized:

• Invasive stage: Individuals may experience pain with/without fever for 7-14 days
• Suppurative stage: Over the next 7-14 days, a slow-growing painful mass forms in the skeletal muscles. The tender mass hardens, and abscess formation occurs that results in fever and other symptoms such as nausea, vomiting, and general illness
• Late stage: An untreated abscess can begin to involve the nearby bones and joint. The condition may further deteriorate and lead to septicemia and other severe complications

How is Tropical Pyomyositis Diagnosed?

The diagnosis of Tropical Pyomyositis is generally challenging. It may be diagnosed on the basis of the following information:

• Complete evaluation of medical history along with a thorough physical exam
• A culture may be performed to confirm the presence of bacteria and to rule-out other causes of infection. In this culture, a small amount of pus or fluid from one of the sores is collected and sent to the lab for testing. The test results can help confirm the presence and type of bacteria
• Aspiration of pus from skeletal muscle abscess or muscle biopsy (in the absence of abscess) to identify the pathogenic bacteria with the help of specific staining and microscopy techniques
• Dermoscopy: It is a diagnostic tool where a dermatologist examines the skin using a special magnified lens
• Wood’s lamp examination: In this procedure, the healthcare provider examines the skin using ultraviolet light. It is performed to examine the change in skin pigmentation
• Imaging studies, such as ultrasound, CT, or MRI scan, of the affected region
• Tissue biopsy, if needed: A tissue biopsy is performed and sent to a laboratory for a pathological examination. The pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Tropical Pyomyositis?

The complications of Tropical Pyomyositis may be significant and may include:

• Severe involvement of the adjacent joint
• Sepsis or blood poisoning
• Kidney failure
• Sudden cardiac arrest

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Tropical Pyomyositis Treated? 

The treatment for Tropical Pyomyositis may include the following:

• If abscess is present, then surgical incision, debridement, and drainage of pus from the affected muscles
• Antibiotics for 3-4 weeks (such as vancomycin and daptomycin)
• Individuals with poor immune systems are treated using broad spectrum antibiotics
• Adequate wound care

The treatment may continue until the affected individual is fever-free for at least 7 days, the leukocyte count is within the normal range, and the wound appears healed and clean.

How can Tropical Pyomyositis be Prevented?

Tropical Pyomyositis may be prevented by:

• Avoiding excessive wear and tear of muscles, and muscle trauma
• Avoiding injectable (and any other form of) illicit drugs
• Seeking early medical attention for skin infections or insect bites
• Managing diabetes for a good glycemic index
• Getting treatment for any underlying medical condition(s) that may decrease immunity in the individual

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Tropical Pyomyositis? (Outcomes/Resolutions)

The prognosis of Tropical Pyomyositis is dependent upon the severity of the signs and symptoms and associated complications, if any.

• An early recognition of the condition and appropriate therapy can result in a good prognosis
• A delayed diagnosis and a lack of appropriate treatment may result in severe complications, particularly in individuals with severe illnesses

It is reported that between 2-10% of the affected and untreated individuals succumb to the infection.

Additional and Relevant Useful Information for Tropical Pyomyositis:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/healthy-living/skin-disorders/