Unexpected source of Proteus mirabilis bacteraemia

Area of Science:

• Cardiology
• Infectious Diseases
• Vascular Surgery

Background:

• Mycotic aneurysms of the thoracic aorta are rare but critical conditions.
• Gram-negative bacteraemia typically originates from intra-abdominal or pelvic sources.

Observation:

• An elderly woman presented with bacteraemia attributed to an infected aneurysm in the thoracic aortic arch.
• The causative agent was identified as Proteus mirabilis, an unusual pathogen for this location.

Findings:

• The intrathoracic origin of Proteus bacteraemia led to diagnostic delays.
• Infected aneurysms, though rare, are a potential source of gram-negative bacteraemia.

Implications:

• This case underscores the importance of considering mycotic aneurysms in unexplained bacteraemia, especially in patients with vascular risk factors.
• Early diagnosis and treatment are crucial for improving outcomes in these high-morbidity cases.