# Epidemiology of Brain Abscess: A Retrospective Cohort From a Neurosurgical Tertiary Referral Center in England

## TL;DR

This study examines the causes, treatment, and outcomes of brain abscesses in a large patient group, highlighting the role of specific bacteria and the potential of molecular diagnostics.

## Contribution

The study provides updated epidemiological data on brain abscesses and highlights the utility of 16S rRNA gene PCR in diagnosis.

## Key findings

- Staphylococcus aureus was the most common cause of postsurgical brain abscesses.
- Streptococcus anginosus caused 42.8% of community-acquired brain abscesses.
- 16S rRNA gene PCR provided new diagnoses in 42.4% of tested cases.

## Abstract

Brain abscess is a serious infection with substantial morbidity and mortality. Current data on the etiology, management, and outcomes are limited. This study describes the epidemiology of brain abscess in a large patient cohort.

This is a retrospective, observational study of brain abscess at a tertiary referral center. Patients were selected using hospital coding. Demographic, clinical, neurosurgical, and microbiological data were analyzed.

We identified 174 patients with brain abscess admitted between 2012 and 2023 (32 pediatric, 142 adults, 66.7% male). Subdural empyema and parenchymal abscess were the most common abscess types in the pediatric and adult cohorts, respectively. A microbiological diagnosis was made in 74.1% of cases. Staphylococcus aureus was the most common cause of postsurgical brain abscess, causing 27.8% of these cases. Streptococcus anginosus caused 42.8% of community-acquired brain abscesses. Microbiological samples were sent for 16S rRNA gene polymerase chain reaction (PCR) testing in 33 cases (19.0%). A new microbiological diagnosis was made in 14 of these 33 cases (42.4%). In-hospital mortality was 13.4%. Increasing age and poor admission Glasgow Coma Score were significantly associated with mortality. A trend toward decreasing mortality was seen with S. anginosus.

Our data reinforce the importance of early diagnosis and multidisciplinary management, particularly in older patients. Molecular diagnostics, including 16S rRNA gene PCR, may play an increasing role in guiding treatment in the future.