Human native endocarditis caused by Streptococcus canis-a case report

Area of Science:

• Cardiology
• Infectious Diseases
• Microbiology

Background:

• Native infective endocarditis (NIE) is a serious heart valve infection.
• Streptococcus canis, a bacterium commonly found in dogs, is a rare cause of human infection, particularly endocarditis.

Observation:

• A 73-year-old woman with close dog contact presented with symptoms suggestive of endocarditis.
• Echocardiography revealed significant mitral annulus calcifications, massive posterior leaflet regurgitation, and adjacent vegetation.
• Blood cultures identified Streptococcus, Lancefield group G.

Findings:

• Molecular detection using broad-range PCR, 16S rRNA, and tuf gene sequencing confirmed Streptococcus canis in the heart valve.
• Despite negative tissue cultures, molecular identification was crucial for diagnosis.
• The patient underwent coronary artery bypass and mitral valve replacement.

Implications:

• This case highlights the potential for zoonotic transmission of Streptococcus canis to cause severe native infective endocarditis.
• It underscores the importance of molecular diagnostic techniques when conventional cultures are negative.
• Prompt surgical intervention and targeted antimicrobial therapy are critical for favorable outcomes in such rare cases.