Invasive Haemophilus influenzae Type F Infection Complicated by Subarachnoid Phlegmon and Cortical Venous Thrombosis

Diagnostic testing Diagnostic testing revealed the source of the boy’s fever was influenza type B. Amoxicillin and oseltamivir were prescribed at that time, and the boy was discharged home. Three days later, the patient presented again for irritability, reduced activity, and respiratory distress associated with right upper lobe superimposed pneumonia. Amoxicillin-clavulonic acid was prescribed at discharge one day later, and oseltamivir was continued for the full 5-day course. During this brief admission, a blood culture was collected, which grew Haemophilus influenza type f (Hif) β-lactamase negative. The next day the patient presented with incessant crying, persistent fever, and jerking movements of the extremities on the right side. The patient was then was readmitted to the hospital. Cerebrospinal fluid (CSF) analysis revealed elevated levels of nucleated cells at 35/mcL with 45% neutrophils, 47% lymphocytes, and 8% monocytes; low level of red blood cells at 4/mcL; decreased CSF glucose level at 47 mg/dL; and normal level of CSF proteins at 41 mg/dL. Organisms were not detected on a Gram stain of the CSF, and results of a meningitis encephalitis panel were negative, including H influenzae polymerase chain reaction assay. A computed tomography (CT) scan of the head showed mild prominence of extra-axial spaces, consistent with benign enlargement of the subarachnoid spaces of infancy. Bacterial growth was not seen on the CSF analysis or on a repeat blood culture. The patient was started on intravenous (IV) ceftriaxone, 100 mg/kg/d, and phenobarbital for seizure management. Three days later, despite a therapeutic phenobarbital level, the patient had a prolonged partial clonic seizure of the left lower extremity that resolved after treatment with lorazepam and extra doses of phenobarbital. A magnetic resonance imaging (MRI) scan of the brain on the day of the seizure showed severe, diffuse leptomeningeal thickening, enhancement of bilateral cerebral hemispheres, and bilateral “subdural fluid collections” (Figure 1). These presumed subdural empyemas were associated with mass effect on the underlying brain but were not associated with transtentorial herniation or hydrocephalus. Immediately, bilateral burr hole craniotomies were performed, and subdural drains were placed. During the surgical procedure to place the drains, solid phlegmon was visualized in the subarachnoid space that could not be removed by suction. On hospital day 4, left upper and lower extremity paresis were noted. An electroencephalogram (EEG) revealed no seizure activity. On hospital day 6, after 3 days of extra-axial drainage, a repeat head MRI scan showed new left frontal cortical venous thrombosis with normal signal in the subadjacent brain parenchyma. Subsequently, enoxaparin was started as anticoagulation therapy. At this time, the patient was also noted to have thrombocytosis with a platelet level of 1214 k/uL and was initiated on aspirin as well. Extra-axial drainage was steady for a 10-day period. A repeat head CT scan on hospital day 10 revealed dilatation of the cerebral ventricles (Figure 2). Therefore, the bilateral subdural drains were removed, and an external ventricular drain was placed and remained in place for 12 days. By hospital day 10, the patient’s left upper extremity had minimal motor Invasive Haemophilus influenzae Type F Infection Complicated by Subarachnoid Phlegmon and Cortical Venous Thrombosis