A case of influenza pneumonia following pneumococcal infection in an adult patient with concurrent encephalopathy with a lesion in the splenium of the corpus callosum

: A 35-year-old male patient had a fever, cough, and other symptoms since the end of December 2010. The patient then developed a high fever and decreased SpO2, suggesting possible pneumonia. The patient was admitted to our hospital on the 6th day of illness. Chest computed tomography revealed multiple infiltrative shadows and ground-glass opacities distributed in a patchy pattern in the bilateral lungs. An atypical pneumonia was suspected, and we initiated antibiotic treatment with minocycline. However, the patient developed consciousness disturbance in the afternoon of the 7th day of illness. The high fever persisted, suggesting the patient's poor response to minocycline treatment, which was then replaced with ciprofloxacin and imipenem/cilastatin on the 8th day of illness. Streptococcus pneumoniae was detected in the blood culture bottles submitted at the time of admission. A head magnetic resonance imaging performed on that day showed a high intensity area in the splenium of the corpus callosum, leading to a diagnosis of encephalopathy. Methylprednisolone pulse therapy and gamma globulin treatment were initiated. The patient then recovered consciousness gradually with improvement of inflammatory responses and imaging findings. Subsequently, an influenza virus (H1N1) antibody level was found to have increased from less than 10 times to 640 times. Thus, it was determined that the patient's pneumonia and encephalopathy were attributable to the influenza A (H1N1) pdm09 virus during the flu season and Streptcoccal infection. Combination therapy, such as steroid pulse treatment, appropriate antibiotics and gamma globulin preparation was effective for both the flu-induced mixed pneumonia and encephalopathy in this patient.