Aggregatibacter aphrophilus Brain Abscess and Ventriculitis in a Young Healthy Woman: A Case Report and Literature Review.

Aggregatibacter aphrophilus is a rare cause of endocarditis and brain abscesses. Common potential risk factors include dental manipulation or disease, upper respiratory infections, proximity to animals, and heart disease. We present a case of a young woman without apparent predisposing factors who developed a deep-seated A. aphrophilus brain abscess complicated by ventriculitis and post-infectious low-pressure communicating hydrocephalus. Diagnosis was established by cerebrospinal fluid (CSF) 16S rDNA sequencing and a serum Karius® cell-free DNA test, suggesting hematogenous spread. Management required a seven-week course of ceftriaxone, adjunctive steroids for refractory inflammation, and neurosurgical interventions, including external ventricular drainage and ventriculoperitoneal shunt placement. This report underscores the diagnostic and therapeutic challenges of this condition and highlights the role of molecular diagnostics in culture-negative infections.