Department: COMBATING INFECTION
A LEADING CAUSE OF life-threatening perinatal infection in the United States, group B streptococcus (GBS) is a naturally occurring bacterium found in 20% to 35% of healthy adults.1,2 It colonizes the rectum, vagina, cervix, and urethra of 15% to 40% of pregnant women. GBS colonization is usually asymptomatic. However, maternal colonization is the primary risk factor for GBS infection in infants younger than 90 days. GBS becomes a health threat when it's transferred from the mother to the newborn either in utero or during childbirth. Newborns who become severely ill with GBS may have ingested infected amniotic fluid or vaginal fluid during birth.3
The primary risk factor for early-onset GBS infection is maternal GBS genitourinary or gastrointestinal colonization. Additional risk factors include:
- prior delivery of an infant with GBS infection
- delivery at less than 37 weeks' gestation
- premature membrane rupture at any gestational age; membrane rupture 18 or more hours before delivery
- GBS bacteriuria during the current pregnancy
- temperature over 100.4° F (38° C) during labor
- sustained intrapartum fetal tachycardia.4
Signs and symptoms
Women with GBS in the rectovaginal area at the time of birth have a 60% chance of transmitting it to the newborn; 1% to 2% of these infants will develop early-onset GBS (presents at or within 24 hours of birth, but can occur through day 6). Late-onset GBS occurs at ages 4 to 5 weeks.4
Sepsis and pneumonia are the most common complications associated with early-onset disease. Although meningitis occurs less frequently, early-onset infections can lead to permanent neurologic complications.1,2 Infants who develop late-onset GBS may develop signs and symptoms after the first week of life. Common signs and symptoms of late-onset GBS include bacteremia without a focus, fever over 100.4° F (38° C), difficulty feeding, difficulty breathing, irritability, lethargy, tachypnea, grunting, apnea, and cyanosis.1,2,4
Assess the newborn for signs and symptoms of respiratory distress (expiratory grunting and cyanosis are commonly seen, as are nasal flaring and chest retractions). Newborns may exhibit signs of thermoregulatory dysfunction. Cardiovascular signs could include hypo- or hypertension and dysrhythmias. Some infants develop tremors or seizures.
Diagnosis and treatment
Infection in the newborn is confirmed by isolating GBS from the infant's blood or cerebrospinal fluid.4
Treatment of neonates with GBS infection consists of antimicrobial therapy, abscess drainage, and strict attention to supportive care, including supporting ventilation, maintaining fluid and electrolyte balance, controlling seizures, and recognizing and treating anemia and shock. GBS is sensitive to penicillin G, ampicillin, extended-spectrum penicillins, first- and second-generation cephalosporins, and vancomycin, but penicillin G is the most narrow-spectrum and active agent in vitro.4
Preventing GBS transmission
When caring for a pregnant patient, an excellent resource is the CDC's guidelines for preventing GBS in newborns. They include the following actions:
- Screen all pregnant women for vaginal and rectal GBS at 35 to 37 weeks' gestation unless they had GBS bacteriuria during the current pregnancy or previous infants with GBS disease.1,2
- As prescribed, administer antibiotics to patients during labor if they have a positive GBS screen during the current pregnancy, unless it's a planned cesarean delivery; have unknown GBS status; or have any of the risk factors mentioned earlier.
Teach your patient about common signs and symptoms of late-onset GBS (fever, irritability, poor feeding). Advise her to call her healthcare provider immediately if she detects any of these signs and symptoms.
1. Centers for Disease Control and Prevention. Group B strep infection in newborns
2. Centers for Disease Control and Prevention. Prevention of perinatal group B streptococcal disease
3. Murray SS, McKinney ES. Foundations of Maternal Newborn Nursing
. 5th ed. St. Louis, MO: Saunders Elsevier; 2009.
4. Puopolo KM, Baker CJ. Group B streptococcal infection in neonates and young infants. UpToDate