Streptococcus pneumoniae Cerebellar Abscess in a Child With Specific Polysaccharide Antibody Deficiency: A Case Report.

Brain abscesses are local pockets of infection within the brain parenchyma, characterized by headaches, fevers, and focal neurological deficits. Here, we present a case of an eight-year-old fully vaccinated male patient who presented to the emergency department with a 1-week history of intermittent generalized headache, photophobia, fatigue, and vomiting. The patient was admitted for further work-up, with subsequent imaging revealing a cerebellar mass consistent with an abscess. Cultures from the abscess fluid grew pan-sensitive Streptococcus pneumoniaeSerotype 3, and the patient was started on a 6-week course of antibiotic therapy, completed via an outpatient peripherally inserted central catheter (PICC) line. Considering that this serotype is one of the 13 serotypes included in the pneumococcal conjugate vaccine 13 (PCV13), potential etiologies for the patient's presentation were proposed, including underlying immunodeficiency. An immunodeficiency work-up diagnosed him with specific polysaccharide antibody deficiency (SPAD) with poor immunologic memory after vaccination against Streptococcus pneumoniae, and Haemophilus influenzae failed to induce robust and durable antibody levels. This case underscores the importance of screening children who were previously immunized with PCV and present with invasive pneumococcal disease (IPD) for underlying immunodeficiency.