Necrotising pyomyositis complicating intramuscular antipsychotic administration

A 26-year-old woman with paranoid schizophrenia was admitted to the medical intensive care unit with septic shock requiring intubation and mechanical ventilation. The source of septic shock was not identified despite obtaining CT of the chest/abdomen/pelvis, bronchoalveolar lavage and microbiological results for tracheal secretions, blood, urine and cervix. An indium-111 tagged white cell count scan was subsequently performed, revealing increased right anterior deltoid uptake. Owing to serial increases (up to 1310 U/L) in serum creatine kinase and a history of local intramuscular paliperidone injections for management of schizophrenia, surgical exploration was performed and identified necrotising skeletal muscle inflammation and extensive fat necrosis with an organising abscess, consistent with pyomyositis. A gram stain of purulent fluid revealed gram-positive cocci, but no organisms grew in culture. The patient recovered after 10 days of daptomycin and 7 weeks of wound care. Paliperidone injections were discontinued and oral risperidone was initiated.