Group B strep disease in newborns

Other Names: Late-onset group B strep disease in newborns Group B strep; GBS; Neonatal sepsis; Neonatal sepsis - strep

Group B streptococcal (GBS) septicemia is a severe bacterial infection that affects newborn infants.

Cause

Septicemia is an infection in the bloodstream that may travel to different body organs. GBS septicemia is caused by the bacterium Streptococcus agalactiae, which is commonly called group B strep, or GBS. GBS is commonly found in adults and older children, and usually does not cause infection. But it can make newborn babies very sick. There are two ways in which GBS can be passed to a newborn baby:

• The baby can become infected while passing through the birth canal. In this case, babies become ill between birth and 6 days of life (most often in the first 24 hours). This is called early-onset GBS disease.
• The infant may also become infected after delivery by coming into contact with people who carry the GBS germ. In this case, symptoms appear later, when the baby is 7 days to 3 months or more old. This is called late-onset GBS disease.

GBS septicemia now occurs less often, because there are methods to screen and treat pregnant women at risk.

Riskfactors

The following increase an infant's risk for GBS septicemia:

• Being born more than 3 weeks before the due date (prematurity), especially if the mother goes into labor early (preterm labor)
• Mother who has already given birth to a baby with GBS sepsis
• Mother who has a fever of 100.4°F (38°C) or higher during labor
• Mother who has group B streptococcus in her gastrointestinal, reproductive, or urinary tract
• Rupture of membranes (water breaks) more than 18 hours before the baby is delivered
• Use of intrauterine fetal monitoring (scalp lead) during labor.

Symptoms

The baby may have any of the following signs and symptoms:

• Anxious or stressed appearance
• Blue appearance (cyanosis)
• Breathing difficulties, such as flaring of the nostrils, grunting noises, rapid breathing, and short periods without breathing
• Irregular or abnormal (fast or very slow) heart rate
• Lethargy
• Pale appearance (pallor) with cold skin
• Poor feeding
• Unstable body temperature (low or high)

Diagnosis

To diagnose GBS septicemia, GBS bacteria must be found in a sample of blood (blood culture) taken from a sick newborn. GBS grows readily on blood agar plates as microbial colonies surrounded by a narrow zone of β-haemolysis. GBS is characterized by the presence in the cell wall of the group B antigen of the Lancefield classification (Lancefield grouping) that can be detected directly in intact bacteria using latex agglutination tests. The CAMP test is also another important test for the identification of GBS. The CAMP factor acts synergistically with the staphylococcal β-haemolysin inducing enhanced haemolysis of sheep or bovine erythrocytes.

GBS is also able to hydrolyse hippurate, and this test can also be used to identify GBS. Haemolytic GBS strains produce an orange-brick-red nonisoprenoid polyene pigment (ornythinrhamnododecaene) (granadaene) when cultivated on granada medium that allows its straightforward identification.

Identification of GBS could also be carried out easily using modern methods as matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Other tests that may be done include:

• Blood clotting tests - prothrombin time (PT) and partial thromboplastin time (PTT)
• Blood gases (to see if the baby needs help with breathing)
• Complete blood count
• CSF culture (to check for meningitis)
• Urine culture
• X-ray of the chest

Treatment

The baby is given antibiotics through a vein (IV). Other treatment measures may involve:

• Breathing help (respiratory support)
• Fluids given through a vein
• Medicines to reverse shock
• Medicines or procedures to correct blood clotting problems
• Oxygen therapy
• A therapy called extracorporeal membrane oxygenation (ECMO) may be used in very severe cases. ECMO involves using a pump to circulate blood through an artificial lung back into the bloodstream of the baby.

Prevention

To help reduce the risk for GBS, pregnant women should get tested for the bacteria at 35 to 37 weeks into their pregnancy. If the bacteria are detected, women are given antibiotics through a vein during labor. If the mother goes into premature labor before 37 weeks and GBS test results are unavailable, she should be treated with antibiotics.

Newborns who are at high risk are tested for GBS infection. They may receive antibiotics through a vein during the first 30 to 48 hours of life until test results are available. They should not be sent home from the hospital before 48 hours of age.

In all cases, proper hand washing by nursery caregivers, visitors, and parents can help prevent the spread of the bacteria after the infant is born.

Early diagnosis can help decrease the risk for some complications.

Prognosis

This disease can be life threatening without prompt treatment.

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