From the Guidelines
Brain abscesses are primarily caused by bacterial infections, with the most frequent causative pathogens being oral cavity bacteria such as Streptococcus anginosus group, Fusobacterium spp., and Aggregatibacter spp., often associated with dental and chronic ear infections. The causes of brain abscess can be categorized into several key areas, including:
- Direct spread from nearby infections like dental infections, chronic ear infections, or other head and neck infections, which are often caused by oral cavity bacteria 1
- Hematogenous spread, where infections elsewhere in the body travel through the bloodstream to the brain, and can be caused by a variety of pathogens, including Staphylococcus aureus and Gram-negative bacilli 1
- Traumatic brain injuries, neurosurgical procedures, or foreign bodies, which can introduce pathogens directly into brain tissue 1 The most common bacterial causes of brain abscess include:
- Streptococcus species
- Staphylococcus aureus
- Anaerobes like Fusobacterium spp.
- Gram-negative organisms like Aggregatibacter spp. In immunocompromised patients, opportunistic pathogens like Nocardia spp. and fungi are more prevalent 1. Predisposing factors for brain abscess include:
- Immunocompromise
- Dental infections
- Chronic ear infections
- Traumatic brain injuries
- Neurosurgical procedures
- Foreign bodies in the brain tissue
- Socio-economic factors and overall health status of populations 1
From the Research
Causes of Brain Abscess
The causes of brain abscess can be attributed to various factors, including:
- Bacterial infections, with species such as Staphylococcus and Streptococcus being the most frequent cause 2
- Fungal and parasitic infections, although less common 3
- Contiguous spread from adjacent infections, such as otitis, sinusitis, or dental infections 4, 5
- Haematogenous dissemination, where bacteria enter the brain through the bloodstream 5
- Neurosurgical procedures or cranial trauma, which can introduce bacteria into the brain 5
- Immunocompromised conditions, which can increase the risk of developing a brain abscess 4
Common Pathogens
Some common pathogens associated with brain abscess include:
- Staphylococcus species, including Staphylococcus epidermidis 6
- Streptococcus species, including oral streptococci and the milleri group 5
- Anaerobes, such as those found in the oral cavity or gastrointestinal tract 5
- Enterobacteriaceae, a family of gram-negative bacteria 5
- Aggregatibacter aphrophilus and Eikenella corrodens, members of the HACEK group 6
Risk Factors
Certain risk factors can increase the likelihood of developing a brain abscess, including: