From the Guidelines
The most likely source of Group B Streptococcus (GBS) bacteremia in a patient is the gastrointestinal tract, with the genitourinary tract being the most common site of secondary spread. This is based on the findings of a study by the Centers for Disease Control and Prevention, which reported that the gastrointestinal tract is the most likely human reservoir of GBS 1. The study also noted that colonization rates can differ among ethnic groups, geographic locales, and by age, but rates are similar for pregnant and nonpregnant women 1. Some key points to consider when evaluating a patient with GBS bacteremia include:
- The gastrointestinal tract is the primary reservoir of GBS, with the genitourinary tract being a common site of secondary spread 1
- Colonization rates of GBS can vary, but approximately 10%-30% of pregnant women are colonized with GBS in the vaginal or rectal area 1
- Early-onset invasive disease occurs in approximately 1%-2% of infants born to colonized parturients 1 It is essential to identify the source of GBS bacteremia through physical examination, blood cultures, urine cultures, imaging studies, and echocardiography if endocarditis is suspected. Prompt treatment is crucial to prevent serious complications, including septic shock, endocarditis, and meningitis.
From the Research
Likely Sources of GBS Bacteremia
The likely sources of Group B streptococcus (GBS) bacteremia in non-pregnant adults include:
- Skin and soft tissue infections, which were the most common sources of GBS bacteremia in a study of 90 episodes of GBS bacteremia in adults 2
- Urinary tract infections, which were also a common source of GBS bacteremia in the same study 2
- Primary bacteremia, which was classified as the source of GBS bacteremia in 50% of the episodes in the study 2
- Other possible sources of GBS bacteremia include:
Underlying Conditions
GBS bacteremia is often associated with underlying conditions, including:
- Liver disease, which was more common in males in the study 2
- Malignancy, which was more common in females in the study 2
- Diabetes mellitus, which was present in 27.5% of patients in another study 3
- Non-hematologic cancer, which was the most frequently associated condition in a study of 32 adult patients with GBS bacteremia 4
Age and Mortality
The risk of GBS bacteremia and mortality increases with age, with the majority of patients being over 50 years old in several studies 2, 3, 4. The overall mortality rate was 18.9% in one study 2 and 33.3% in another study 3.