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Updated: Aug 15, 2026

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Published on: June 4, 2012
[Mitral endocarditis secondary to Streptococcus mitis bacteremic pneumonia]
M A Márquez Lorente1, L Flores Meneses, C Carratalá Blasco
1Servicio de Medicina Interna y Enfermedades Infecciosas, Hospital Universitario del Mar, Universidad Autónoma, Barcelona.
Streptococcus mitis, a type of viridans group streptococci, can cause pneumonia and endocarditis. This study highlights its role as a respiratory pathogen, emphasizing endocarditis risk in bacteremic infections.
Area of Science:
- Infectious Diseases
- Cardiology
- Pulmonology
Background:
- Viridans group streptococci are common causes of dental infections and endocarditis.
- Their role as primary respiratory pathogens is less understood.
- Streptococcus mitis is a species within this group.
Observation:
- Two patients presented with pneumonia caused by Streptococcus mitis.
- Both patients subsequently developed mitral endocarditis.
- Septic pulmonary emboli were ruled out as the cause of pneumonia.
Findings:
- This case series supports Streptococcus mitis as a direct respiratory pathogen.
- Bacteremic pneumonia due to S. mitis can lead to secondary endocarditis.
- The study demonstrates the pathogenicity of S. mitis in the respiratory tract.
Implications:
- Clinicians should consider S. mitis in respiratory infections, especially in patients with cardiac risk factors.
- Early recognition and treatment of S. mitis bacteremia are crucial to prevent endocarditis.
- This reinforces the importance of identifying viridans group streptococci in blood cultures.
Related Concept Videos
Mitral Regurgitation I: Introduction
Mitral Stenosis I: Introduction
Mitral Stenosis II: Clinical features and Diagnostic Tests
Mitral Stenosis III: Medical Management
Mitral Stenosis IV: Nursing Management
Endocarditis I: Introduction

