Streptococcus agalactiae
(Redirected from Group B streptococci)
- Bacteria called group B Streptococcus (group B strep, GBS) commonly live in people’s gastrointestinal and genital tracts.
- The gastrointestinal tract is the part of the body that digests food and includes the stomach and intestines.
- The genital tract is the part of the body involved in reproduction and includes the vagina in women.
- Most of the time the bacteria are not harmful and do not make people feel sick or have any symptoms.
- Sometimes the bacteria invade the body and cause certain infections, which are known as GBS disease.
Cause[edit | edit source]
Streptococcus agalactiae or group B Streptococcus (group B strep, GBS) cause GBS disease.
Incidence[edit | edit source]
Approximately 30,800 cases of invasive GBS disease occur annually in the United States in all age groups.
Types of Infections[edit | edit source]
GBS bacteria can cause many types of infections:
- Bacteremia and sepsis
- Bone and joint infections
- Meningitis
- Pneumonia
- Skin and soft-tissue infections
GBS most commonly causes bacteremia, sepsis, pneumonia, and meningitis in newborns. It is very uncommon for GBS to cause meningitis in adults.
Risk factors[edit | edit source]
GBS disease is most common in newborns. There are factors that can increase a pregnant woman’s risk of having a baby who will develop GBS disease, including:
- Testing positive for GBS bacteria late in pregnancy
- Developing a fever during labor
- Having 18 hours or more pass between when their water breaks and when their baby is born
Other medical conditions that put adults at increased risk include:
- Diabetes
- Heart disease
- Congestive heart failure
- Cancer or history of cancer
- Obesity
Risk for serious GBS disease increases as people get older.
Transmission[edit | edit source]
- GBS bacteria commonly live in people’s gastrointestinal and genital tracts.
- The gastrointestinal tract is the part of the body that digests food and includes the stomach and intestines.
- The genital tract is the part of the body involved in reproduction and includes the vagina in women.
- The bacteria do not spread through food, water, or anything that people might have come into contact with.
- How people get these bacteria or spread them to others is generally unknown.
- Most babies who get GBS disease in the first week of life (early-onset) are exposed to the bacteria this way.
- Babies who develop GBS disease from the first week through three months of life have late-onset disease.
- The bacteria may have come from the mother during birth or from another source.
- Other people that live with someone who has GBS bacteria, including other children, are not at risk of getting sick.
Signs and symptoms[edit | edit source]
In Newborns and Their Mothers The symptoms of GBS disease can seem like other health problems in newborns and babies. Symptoms include:
- Fever
- Difficulty feeding
- Irritability or lethargy
- Difficulty breathing
- Blue-ish color to skin
- Babies who get it in the first week of life have “early-onset GBS disease.”
Symptoms of bacteremia (blood stream infection) and sepsis (the body’s extreme response to an infection) include:
- Fever
- Chills
- Low alertness
Symptoms of pneumonia:
- Fever
- Chills
- Cough
- Rapid breathing or difficulty breathing
- Chest pain
Skin and soft-tissue infections:
- Red
- Swollen or painful
- Warm to the touch
- Full of pus or other drainage
- People with skin infections may also have a fever.
Bone and joint infections:
- Fever
- Chills
- Swelling
- Stiffness or inability to use the affected limb or joint
Lab tests[edit | edit source]
A culture and sensitivity test is usually performed of the blood, urine or CSF. It can take a few days to get these results since the bacteria need time to grow. Sometimes GBS bacteria can cause urinary tract infections when a sample of urine to diagnose urinary tract infections.
=CAMP test[edit | edit source]
- If the laboratory is not able to identify group B streptococci (GBS) by the Lancefield grouping procedure, there are other microbiologic tests that can be used to identify GBS. This picture shows one of these tests.
- It is called the CAMP test where CAMP is an acronym for the authors of this test (Christie, Atkinson, Munch, Peterson).
- The CAMP test takes advantage of the capacity of GBS to produce this CAMP factor; most other hemolytic streptococci do not produce CAMP factor. This picture shows the group B Streptococcus (on the right) and a group A Streptococcus (GAS) (on the left).
- Down the middle we have inoculated the plate with a Staphylococcus aureus strain (vertical streak).
- We then inoculated the GBS (on right) and GAS (on left) perpendicular to the Staphylococcus streak.
- We inoculated the agar plate so as not to touch the two different organisms (Staphylococcus and Streptococcus) but to come close to each other.
- The Staphylococcus is used because it produces a lysin that only partially lyses the red blood cells (called beta-lysin).
- The CAMP factor reacts with the partially lysed area of the blood agar plate to enhance the hemolytic activity.
Treatment[edit | edit source]
- Treatment is with antibiotics such as beta-lactams, which includes penicillin and ampicillin.
- Sometimes people with soft tissue and bone infections may need additional treatment, such as surgery.
- Treatment will depend on the kind of infection caused by GBS bacteria.
- Patients should ask their or their child’s doctor about specific treatment options.
Complications[edit | edit source]
- Active surveillance for invasive GBS disease is ongoing in a multistate population.
- Neurologic sequelae include sight or hearing loss and cerebral palsy.
- Death occurs in about 5% of infants and adults.
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