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Bacteremic community-acquired pneumonia due to viridans group streptococci
1Department of Medicine, Dalhousie University, Halifax, Nova Scotia.
Abstract:
We studied 1118 patients with community-acquired pneumonia who were admitted to our hospital over an 8-y period. Seventy-six of the 1118 patients were bacteremic and 7 (9.2%) of these had blood cultures positive for various viridans streptococci. Four had polymicrobial bacteremia (S. mitis, S. sanguis 1, S. sanguis II; S. mitis, S. sanguis II; S. MG; S. sanguis II, Neisseria sp; S. intermedius, S. aureus). For 3 of the 7, viridans streptococci were the only agents implicated in the etiology of the pneumonia. These patients were classified as definite viridans streptococcal pneumonia; the remaining 2 were probably and 2 were possibly due to these micro-organisms. The 5 males and 2 females had a mean age of 61.8 y. The mortality rate was 28%. All were febrile and had elevated white blood cell counts. The 5 who had arterial blood gas measurements performed were hypoxemic pO2 34-68 torr. The chest radiographs were not distinctive--a segmental alveolar opacity was the most common abnormality. We conclude that viridans streptococci rarely cause bacteremic community-acquired pneumonia. There are no distinctive clinical or radiographic features of this type of pneumonia.
Insights
Viridans streptococci rarely cause bacteremic community-acquired pneumonia. This rare infection in pneumonia patients has no distinct clinical or radiographic features, leading to a high mortality rate.
Area of Science:
- Infectious Diseases
- Microbiology
- Pulmonology
Background:
- Community-acquired pneumonia (CAP) is a significant cause of morbidity and mortality.
- Bacteremia complicates CAP in a subset of patients, necessitating identification of causative pathogens.
- Viridans streptococci are common commensals but rarely implicated as primary pathogens in severe pneumonia.
Observation:
- A retrospective study analyzed 1118 patients with CAP over 8 years.
- Blood cultures revealed viridans streptococci in 7 (9.2%) of 76 bacteremic patients.
- These 7 patients included definite, probable, and possible cases of viridans streptococcal pneumonia.
Findings:
- The 7 patients with viridans streptococcal bacteremia were older (mean age 61.8 years) with a high mortality rate (28%).
- Clinical presentation included fever and elevated white blood cell counts.
- Hypoxemia was common (pO2 34-68 torr), and chest radiographs showed non-specific segmental alveolar opacities.
Implications:
- Viridans streptococci are an uncommon cause of bacteremic CAP.
- No specific clinical or radiographic features can reliably identify this etiology.
- The high mortality underscores the importance of considering less common pathogens in severe pneumonia.