<s>[INST] context: Tropical pyomyositis, a disease often seen in tropical countries, is characterised by suppuration within skeletal muscles, manifesting as single or multiple abscesses. The most common organism implicated is Staphylococcus aureus. In 20%-50% of cases there is a history of trauma to the affected muscles. Commonly involved muscles are quadriceps, glutei, pectoralis major, serratus anterior, biceps, iliopsoas, gastrocnemius, abdominal and spinal muscles. Early diagnosis is often missed because of lack of specific signs, unfamiliarity with the disease, atypical manifestations, and a wide range of differential diagnosis. Diagnostic techniques like ultrasound and computed tomography/magnetic resonance imaging are very useful in diagnosis. The diagnosis is confirmed either by biopsy or aspiration of pus from the affected muscles. The initial antibiotic of choice is cloxacillin. Incision and drainage are important components of management. Treatment for Gram negative or anaerobic organisms should be instituted, whenever indicated. Physicians should become more familiar with this potentially life threatening but curable infective disease entity. [/INST] question: Which is the most common micro-organism known to cause tropical pyomisitis? | options: A: Streptococcus viridans B: Staphylococcus albus C: Klebsiella pneumoniae D: Staphylococcus aureus | answer: D </s>