PYOMYOSITIS

Issah J. kiswagala

(M.B.B.S)

DEFINITION

• Pyomyositis is a bacterial infection of the skeletal muscles which results in an abscess. Pyomyositis is most common in tropical areas but can also occur in temperate zones.
• It is infection and suppuration with destruction of the skeletal muscle, commonly due to Staphylococcus aureus and Streptococcus pyogenes, occasionally due to gram-negative organisms.
• It is common in muscles of thigh, gluteal region, shoulder and arm.

EPIDEMIOLOGY

• Pyomyositis is classically an infection of the tropics, although it has been recognized in temperate climates with increasing frequency.
• Tropical pyomyositis primarily occurs in two age groups: children (ages 2 to 5) and adults (ages 20 to 45), while the majority of temperate pyomyositis cases occurs in adults.
• Males appear to be more commonly affected than females

AETIOLOGY/PREDISPOSING FACTORS

• Immunodeficiency/Immunocompromised conditions.
• Trauma
• IV drug abusers are often affected
• Malnutrition
• Concurrent infection

BACTERIOLOGY

• Staphylococcus aureus (90%),
• Streptococcus pyogenes
• E.coli

CLINICAL FEATURES

• Muscles are painful, swollen, tender, and indurated.
• Classically quadriceps, gluteus, shoulder and upper arm muscle are affected.
• Quadriceps muscle is involved most commonly, The second most common location is the psoas muscle, followed by the upper extremities.
• Fever, malaise and jaundice.
• Spasm of muscles are characteristic.
• Renal failure follows soon.

DIFFERENTIAL DIAGNOSIS

• Metabolic Myopathies
• Polymyositis
• Neuromuscular and Myopathic Complications of HIV
• Femoral Mononeuropathy

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INVESTIGATIONS

• Complete blood count (Leukocytosis).
• Elevated erythrocyte sedimentation rate (ESR).
• Elevated muscle enzyme levels - Creatine kinase can go up to 50,000 to 2,00,000 units/L during acute phase due to rhabdomyolysis.
• Purulent material for Gram stain, anaerobic and aerobic cultures, antimicrobial sensitivity testing.
• MRI is the imaging modality of choice for the diagnosis of pyomyositis

DIAGNOSIS

Key historical points should be confirmed.

• Risk factors for Staphylococcus aureus pyomyositis - Strenuous activity, muscle trauma, skin infections, infected insect bites, illicit drug injections, connective tissue disorders, and diabetes

TREATMENT

• Early diagnosis and early aggressive treatment
• Antibiotics initially are given intravenously until clinical improvement is noted, followed by oral antibiotics for a total course of 2 weeks.

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Surgical Treatment

• Drain pus from Abscess

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Pharmacological treatment

• Flucloxacillin 250mg and Amoxycillin 250mg PO 8 hourly for 2 weeks

OR

• Erythromycin 500mg PO 8 hourly for 2 weeks

In children

• Cloxacillin 25mg/kg (IV) 8 hourly for 2 weeks

OR

• Erythromycin 10mg/kg 8 hourly for 2 week

PROGNOSIS�

• Prompt administration of antibiotics can result in complete resolution of pyomyositis.

FOLLOW UP

• Frequency of follow-up visits is contingent upon the patient's rate of progression and need for symptom control.

COMPLICATIONS

•  Bacteremia
• Toxic shock syndrome
• Multiorgan failure

SUMMARY