Acute encephalitis caused by Streptococcus pneumoniae: case report and review of the literature

Abstract

Introduction: Streptococcus pneumoniae (pneumococcus), is a Gram-positive, spherical bacteria, member of the genus Streptococcus. It resides asymptomatically in healthy carriers typically colonizing the respiratory tract, sinuses, and nasal cavity. However, in susceptible individuals with weaker immune systems, pneumococcus may become pathogenic and spread to other locations causing cardiorespiratory and bone diseases as well as meningitis. Encephalitis and brain abscesses caused by Streptococcus pneumoniae are rare entities and they account for less than 1% of all bacterial brain abscesses. Purpose: We aim to present a case report of an acute encephalitis in a 16 years old female patient caused by Streptococcus pneumoniae, with review of the literature. Case Report: A 16 years old, right-handed female, was hospitalized at the clinic due to impaired consciousness (coma) and decerebrate posturing. The symptoms started the previous days with vomiting, drowsiness, subfebrile temperature and were originally perceived as food poisoning. Laboratory blood analysis were normal at the beginning and despite supportive therapy, deterioration of the clinical condition occurred, followed by confusion, muscle weakness and collapse. These symptoms were initially addressed as a functional neurological symptom disorder and the patient was referred to a psychiatrist. However, the patient’s condition got worse, with febrile symptoms, while the control laboratory blood examination showed signs of infectious syndrome. The patient was seen by infectologist and COVID-19 test was performed, with negative result. The analysis of CSF found bacterial infiltration, while the PCR test isolated Streptococcus pneumoniae. MRI of the brain (native and with contrast) showed bilateral multiple microabscesses, predominantly in the frontal and parietal regions. After the diagnosis was confirmed, the patient was treated promptly with antiedematous, antibiotic, neuroprotective and other symptomatic therapy for a period of 2 months. Her condition gradually improved completely, with amelioration of the state of consciousness and muscle weakness as well. Control laboratory blood analysis and CSF examination showed improvement as well, while the MRI of the brain displayed reduction of the previously described lesions and edema. Conclusion: The atypical clinical picture may sometimes mislead the treating physician. Cases with encephalitis caused by Streptococcus pneumoniae have been rarely described in the literature, however, early recognition and adequate treatment are crucial for the positive outcome.