Actinomyces israelii Brain Abscess With Advanced HIV Disease.

We present the first reported case of a pediatric central nervous system (CNS) abscess caused by Actinomyces israelii in the context of advanced HIV disease. A three-year-old girl from São Tomé and Príncipe presented with progressive neurological deficits, including gait instability and language delay. Brain MRI revealed a right temporal lobulated lesion with surrounding edema and mass effect. Chronic superior sagittal sinus thrombosis and hydrocephalus were also identified. Neurosurgical intervention included ventriculocisternostomy and microsurgical resection of the lesion, which revealed a multiloculated abscess. Histology confirmed granuloma formation, and polymerase chain reaction (PCR) identified A. israelii. HIV serology was positive, with a CD4 count of 664 cells/μL and a viral load of 1,340,000 copies/mL. The patient received a year-long antibiotic regimen, starting with intravenous penicillin G followed by oral amoxicillin, and antiretroviral therapy was initiated. She showed marked improvement in neurological function and no signs of relapse after one year. This case underscores the importance of considering A. israelii in the differential diagnosis of CNS lesions in immunocompromised pediatric patients. It also highlights the critical role of neurosurgery, molecular diagnostics, and multidisciplinary management in ensuring favorable outcomes.