Distribution of streptococcal groups causing infective endocarditis: a descriptive study

Area of Science:

• Infectious Diseases
• Microbiology
• Cardiology

Background:

• Infective endocarditis (IE) is a serious infection of the heart's inner lining.
• Accurate identification of causative pathogens is crucial for effective treatment and understanding disease epidemiology.
• Streptococci are a significant group of bacteria implicated in IE.

Purpose of the Study:

• To delineate the distribution of streptococcal species responsible for infective endocarditis.
• To provide updated epidemiological data on streptococcal IE pathogens.
• To compare the diagnostic utility of different microbiological methods.

Main Methods:

• Retrospective analysis of 296 patients with definite infective endocarditis (July 2007 - December 2014).
• Microbial identification using blood culture, valve culture, and valve polymerase chain reaction (PCR).
• Categorization of streptococci into viridans, pyogenic, nutritionally variant, and anaerobic groups.

Main Results:

• Streptococci accounted for a substantial proportion of IE cases.
• Viridans group streptococci were the most prevalent (76%), followed by pyogenic (17%).
• Within the viridans group, Streptococcus mitis group was the most common (61%).
• Streptococcus agalactiae was the predominant pyogenic streptococcus (78%).
• Polymerase chain reaction (PCR) demonstrated higher sensitivity than culture for identifying streptococci in excised heart valves.

Conclusions:

• Viridans group streptococci, particularly Streptococcus mitis group, are the leading cause of streptococcal infective endocarditis.
• Pyogenic streptococci, notably Streptococcus agalactiae, also contribute significantly to IE.
• Polymerase chain reaction (PCR) offers improved sensitivity for pathogen detection in cardiac tissue compared to traditional culture methods.