Title : Encephalopathy: An unusual presentation of MRSA osteomyelitis and sepsis
Sepsis associated encephalopathy (SAE) is diffuse brain dysfunction that occurs secondary to an infection but not directly in the CNS1-2. We present a case of SAE caused by MRSA osteomyelitis and septic shock.
15 year old female who is a volley ball player presented with a 2-day history of personality change. She had fatigability which progressed to decreased alertness and monosyllabic speech. History is remarkable for visit to the emergency department and Orthopedic Surgeon within the week prior to presentation for left knee pain. Knee radiograph was normal. She was prescribed Percocet as needed followed by Medrol Dosepak and Flexeril.
Current admission, she was febrile to 39.40C and tachycardic at 148 beats/min. Physical examination was significant for obtunded female, GCS 11 and mild edema of left knee. Blood investigations showed: WBC 13000/uL, neutrophils 88%, hemoglobin 8.3 g/dl, platelet 81000/uL, sodium 132 mEq/L, creatinine 0.90 mg/dL, AST 79 U/L, ALT 42 U/L, CPK 1326 mcg/L, C-reactive protein 19 mg/dL, sedimentation rate 87 mm/h and procalcitonin 43ng/mL. Chest radiograph revealed multifocal peripheral areas of patchy nodular infiltrates (Fig. 1) and venous Doppler ultrasound of left lower extremity showed non occlusive thrombus in the left common femoral vein. Cerebrospinal fluid and additional imaging: CT Brain, MRI Brain/Neck, Video EEG and Echocardiogram with bubble study were normal. Blood culture was taken. Patient was started on Lovenox, ceftriaxone and vancomycin.
At 15 hours, blood culture resulted positive for gram positive cocci. Antibiotics were switched to ceftaroline and clindamycin on suspicion of MRSA. Due to concern for necrotizing fasciitis, MRI of lower extremity done and revealed left distal femur osteomyelitis with subperiosteal
abscess to posterior aspect of distal femur measuring 17.2x3.4x1.5cm (Fig. 2). Specimen from open incision and drainage grew MRSA. Patient managed for septic shock with postulated sepsis associated encephalopathy.
She showed clinical improvement but may be exhibiting early signs of cognitive impairment. Inpatient care continues at the time of abstract submission.
SAE is a diagnosis of exclusion and requires a thorough evaluation for other etiology of delirium. The pathogenesis is not yet fully understood and data in the literature is limited. Our patient presented with encephalopathy therefore, our work up centered on identifying primary CNS infection, endocarditis, paradoxical embolism, seizure, ingestion as well as Macrophage Activation Syndrome (MAS) given the marked hyper inflammatory state. The prompt to evaluate for other sources of infection came after diagnosed bacteremia in the setting of elevated muscle enzyme. Sepsis is a significant cause of morbidity and mortality, it requires prompt identification in order to tailor antimicrobial treatment. Encephalopathy was the first sign of sepsis in this patient. SAE is an entity that requires further studies to determine risk factors, prognosis and guide rehabilitation.
The case is also unique because patient presented with triad of acute osteomyelitis, deep vein thrombosis and septic pulmonary embolism which is rare in the pediatric population.
SAE though uncommon is the first sign of sepsis in susceptible patients and warrants further studies to determine short and long term sequelae.