Streptococcus zooepidemicus (group C) pneumonia in a human

Area of Science:

• Medicine
• Infectious Diseases
• Pulmonology

Background:

• Pneumonia is a common respiratory infection, with Streptococcus pneumoniae being a leading cause.
• Streptococcal pneumonia can be caused by various Lancefield groups, including A and C.
• Group C streptococcal infections are less common but can cause severe disease.

Observation:

• A previously healthy young adult presented with symptoms suggestive of pneumonia.
• The patient had recent close contact with a sick horse, a potential source of zoonotic infection.
• Clinical presentation included gradual illness onset, rapid pleural fluid accumulation, and empyema.

Findings:

• The patient was diagnosed with Lancefield group C streptococcal pneumonia.
• Pneumonia caused by Group C Streptococcus is clinically indistinguishable from classic Group A Streptococcus pneumonia.
• Beta-hemolytic streptococci were identified in sputum, transtracheal aspirates, pleural fluid, and blood samples.

Implications:

• Accurate identification of the specific Lancefield group of beta-hemolytic streptococci is crucial for appropriate patient management.
• The precipitin method of Lancefield or its rapid modifications should be used for grouping beta-hemolytic streptococci in pneumonia cases.
• This case underscores the potential for zoonotic transmission of Group C Streptococcus and the importance of considering non-pneumococcal causes of severe pneumonia.