Dr Anurag Awasthi
Pyomyositis is common in tropical regions but is rarely reported in temperate climates. Staphylococcus aureus was the causative organism in 70 percent of cases.
It is often hematogenous in origin and typically associated with abscess formation.
Males appear to be more commonly affected than females. Most patients with tropical pyomyositis are otherwise healthy without underlying comorbidities, while most patients in temperate regions are immunocompromised or have other serious underlying conditions.
Predisposing factors for pyomyositis include immunodeficiency, trauma, injection drug use, concurrent infection, and malnutrition.
Normal muscle, if damaged, is susceptible to haematogenous invasion by bacteria with subsequent abscess formation. In 20%–50% of cases, a history of blunt trauma or vigorous exercise of the involved group of muscles is forthcoming.
In early stages of tropical pyomyositis, muscles show oedematous separation of fibres, followed by patchy myocytolysis progressing to complete disintegration. The fibres are surrounded by lymphocytes and plasma cells. Muscle fibres may heal without abscess formation or degenerate, progressing to suppuration with bacteria and polymorphonuclear leucocytes.
Maximum incidence is seen at 10–40 years of age with a male to female ratio of 1.5:1. Muscles frequently involved are quadriceps, glutei, pectoralis major, serratus anterior, biceps, iliopsoas, gastrocnemius, abdominal and spinal muscles. Usually, a single group of muscle is affected, but in 12%–40% of cases multiple groups are involved either sequentially or simultaneously.
In an asymptomatic patient with muscle mass and no other features of infection (fever, chills, erythema) but who has leucocytosis and raised erythrocyte sedimentation rate, pyomyositis should be suspected.
Surgical debridement and drainage, accompanied by parenteral antistaphylococcal β-lactamase resistant penicillin (cloxacillin 1–2 g every six hours), is the initial recommended treatment. For methicillin resistant staphylococcus, vancomycin in a dose of 15 mg/kg to a maximum of 1 g, given every 12 hours is a suitable alternative.
Secondary spread of metastatic infection from involved muscles usually requires four to six weeks of parenteral high dose antimicrobial therapy. Otherwise, treatment should be continued till wound is clean, the leucocyte count becomes normal, and the patient is afebrile for 7–10 days. Continuation or recurrence of fever after surgical drainage while the patient is receiving appropriate antimicrobials suggests the presence of other foci, development of drug resistance or, less commonly, drug fever.
It is often hematogenous in origin and typically associated with abscess formation.
Males appear to be more commonly affected than females. Most patients with tropical pyomyositis are otherwise healthy without underlying comorbidities, while most patients in temperate regions are immunocompromised or have other serious underlying conditions.
Predisposing factors for pyomyositis include immunodeficiency, trauma, injection drug use, concurrent infection, and malnutrition.
Normal muscle, if damaged, is susceptible to haematogenous invasion by bacteria with subsequent abscess formation. In 20%–50% of cases, a history of blunt trauma or vigorous exercise of the involved group of muscles is forthcoming.
In early stages of tropical pyomyositis, muscles show oedematous separation of fibres, followed by patchy myocytolysis progressing to complete disintegration. The fibres are surrounded by lymphocytes and plasma cells. Muscle fibres may heal without abscess formation or degenerate, progressing to suppuration with bacteria and polymorphonuclear leucocytes.
Maximum incidence is seen at 10–40 years of age with a male to female ratio of 1.5:1. Muscles frequently involved are quadriceps, glutei, pectoralis major, serratus anterior, biceps, iliopsoas, gastrocnemius, abdominal and spinal muscles. Usually, a single group of muscle is affected, but in 12%–40% of cases multiple groups are involved either sequentially or simultaneously.
In an asymptomatic patient with muscle mass and no other features of infection (fever, chills, erythema) but who has leucocytosis and raised erythrocyte sedimentation rate, pyomyositis should be suspected.
Surgical debridement and drainage, accompanied by parenteral antistaphylococcal β-lactamase resistant penicillin (cloxacillin 1–2 g every six hours), is the initial recommended treatment. For methicillin resistant staphylococcus, vancomycin in a dose of 15 mg/kg to a maximum of 1 g, given every 12 hours is a suitable alternative.
Secondary spread of metastatic infection from involved muscles usually requires four to six weeks of parenteral high dose antimicrobial therapy. Otherwise, treatment should be continued till wound is clean, the leucocyte count becomes normal, and the patient is afebrile for 7–10 days. Continuation or recurrence of fever after surgical drainage while the patient is receiving appropriate antimicrobials suggests the presence of other foci, development of drug resistance or, less commonly, drug fever.
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