Most Common Source of Group C Streptococcal Bacteremia
The upper respiratory tract is the most common source of Group C streptococcal bacteremia, accounting for approximately 20.5% of cases, followed closely by the gastrointestinal tract (18.2%) and skin/soft tissue infections (17.1%). 1
Primary Sources of Infection
Group C streptococcal bacteremia originates from three main anatomical sites with relatively similar frequencies:
- Upper respiratory tract (20.5%): This represents the single most common identifiable source, though pharyngitis itself is typically a localized infection that rarely progresses to bacteremia 1
- Gastrointestinal tract (18.2%): The GI tract serves as a significant portal of entry, particularly in patients with underlying bowel pathology or mucosal compromise 1
- Skin and soft tissue (17.1%): Cutaneous sources including cellulitis, wounds, and skin lesions are common entry points 1, 2
Clinical Context and Risk Factors
The majority of patients with Group C streptococcal bacteremia (72.7%) have significant underlying diseases that predispose them to invasive infection 1:
- Cardiovascular disease (20.5%): The most common comorbidity, which also correlates with the high rate of endocarditis as a clinical manifestation 1
- Malignancy (20.5%): Particularly important in neutropenic patients where bacteremia may occur without an identifiable source 3
- Chronic cardiopulmonary disease, diabetes, and alcoholism: Additional major risk factors 3
Common Clinical Manifestations
Once bacteremia occurs, the most frequent presentations are:
- Endocarditis (27.3%): The most common clinical syndrome associated with Group C bacteremia 1
- Primary bacteremia (22.7%): No identifiable source despite thorough evaluation 1
- Meningitis (10.2%): A serious but less common manifestation 1
Important Clinical Distinctions
Group C streptococcus as a cause of pharyngitis does NOT typically lead to bacteremia. While Group C streptococcus is recognized as a relatively common cause of acute pharyngitis in college students and adults, including food-borne outbreaks from contaminated unpasteurized milk, these pharyngeal infections are generally localized 4. The pharyngitis caused by Group C streptococcus does not lead to complications like acute rheumatic fever, and bacteremia from pharyngitis alone is uncommon 4.
Nosocomial Considerations
- 26% of Group C streptococcal infections are nosocomially acquired 3
- Polymicrobial infections are frequent, most commonly with gram-negative enteric bacilli 3
- Animal exposure history is reported in 23.9% of cases, suggesting zoonotic transmission in some instances 1
Mortality and Prognosis
The overall mortality rate is substantial at 25%, with particularly poor outcomes in: