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Prospective study of Streptococcus milleri bacteremia
E Casariego1, A Rodriguez, J C Corredoira
1Department of Internal Medicine, Hospital Xeral, Lugo, Spain.
Abstract:
In a prospective study of bacteremia caused by organisms of the Streptococcus milleri group a total of 32 adult patients were observed over a seven-year period. These patients accounted for 1.6% of all patients diagnosed as having significant bacteremia and 17% of all cases of streptococcal (nonpneumococcal) bacteremia diagnosed during the study period. Only five patients had polymicrobic bacteremia. In 31 cases, a presumed origin of infection was identified, generally oral or gastrointestinal disease. There were only six cases of nosocomial acquisition. The most common presenting symptom was prolonged fever. The following forms of presentation were documented: bacteremia with local suppurative infection (56%), bacteremia without local suppurative infection (25%), and endocarditis (19%). An associated focus of infection was found in the abdominal cavity in 20 cases (62%). The mortality rate was 12.5%. All isolates were susceptible to penicillin. Caution is necessary in interpreting a blood culture positive for Streptococcus milleri group organisms, since, unlike other viridans streptococci, they are rarely contaminants. For this reason patients with suppurative processes and/or digestive tract disease must be carefully investigated.
Insights
Streptococcus milleri group bacteremia, often linked to oral or GI issues, presents with fever and can cause serious infections. Penicillin is effective, but prompt investigation is crucial as these bacteria are rarely contaminants.
Area of Science:
- Infectious Diseases
- Microbiology
- Clinical Medicine
Background:
- Streptococcus milleri group (SMG) are part of the viridans streptococci, commonly found in the oral and gastrointestinal tracts.
- Bacteremia caused by SMG is less common than other streptococcal bacteremias but can lead to significant clinical manifestations.
Purpose of the Study:
- To characterize the clinical features, sources, and outcomes of bacteremia caused by Streptococcus milleri group organisms.
- To assess the significance of SMG bacteremia and differentiate it from contaminants.
Main Methods:
- Prospective observational study over seven years.
- Inclusion of 32 adult patients with significant bacteremia.
- Analysis of clinical presentation, origin of infection, and antimicrobial susceptibility.
Main Results:
- SMG bacteremia accounted for 1.6% of significant bacteremias and 17% of nonpneumococcal streptococcal bacteremias.
- Common origins included oral and gastrointestinal diseases; prolonged fever was the most frequent symptom.
- Suppurative infections (56%) and abdominal foci (62%) were common; mortality rate was 12.5%.
- All isolates were susceptible to penicillin.
Conclusions:
- Streptococcus milleri group bacteremia is typically associated with underlying suppurative or digestive tract disease.
- Unlike other viridans streptococci, SMG in blood cultures are rarely contaminants and warrant thorough investigation.
- Prompt identification and management are essential due to potential for severe outcomes.