Zoonotic aortic graft infection by Streptococcusequi.

Zoonotic infection of aortic graft by Streptococcus equi is a rare but serious complication in a patient with a history of aortic arch replacement. The infection led to life-threatening complications requiring emergency surgery and appropriate antibiotic treatment.

Background and Patient History

• The patient: a 69-year-old woman with hypertension.
• Previous surgery: total arch replacement with an open stent graft performed 7 years ago.
• Occupational exposure: worked as a horse trainer, indicating close contact with horses.

Clinical Presentation and Diagnostic Findings

• Initial symptoms: fever over 38°C and cough, prompting hospital referral.
• Imaging results:
  • Chest radiography showed a prominent aortic arch, suggesting abnormality.
  • Contrast-enhanced computed tomography (CT) revealed:
    • Enlargement of the aortic arch.
    • Peri-graft fluid collection containing air, indicative of infection around the graft.
• Diagnosis: suspicion of graft infection based on imaging findings.

Microbiological Findings

• Blood cultures identified Streptococcus equi subspecies zooepidemicus, a zoonotic pathogen often associated with horses.
• Intraoperative cultures from the graft also grew the same organism, confirming the infection source.

Clinical Course and Treatment

• On hospital day 6, the patient developed severe hemoptysis (coughing up blood), a critical symptom due to an aortobronchial fistula.
• The fistula was caused by stent graft infection compromising the aortic arch and adjacent bronchus.
• An emergency re-replacement of the aortic arch was performed to manage the fistula and remove infected graft material.
• Post-surgery, the patient received antibiotic therapy with ampicillin targeting Streptococcus equi.
• The postoperative course was uneventful, indicating successful infection control and recovery.

Significance and Implications

• Aortic graft infections, especially with zoonotic organisms like Streptococcus equi, are extremely rare.
• Close contact with animals, such as horses, can be a risk factor for zoonotic infections in postoperative patients.
• Prompt diagnosis combining clinical symptoms, imaging, and cultures is critical for effective intervention.
• Emergency surgical intervention combined with targeted antibiotics can successfully treat such complex infections.
• This case highlights the need for awareness among clinicians regarding zoonotic pathogens causing vascular graft infections in patients with relevant exposures.