Overview
Definition:
Early-onset Group B Streptococcus (GBS) disease is a serious bacterial infection in neonates, typically presenting within the first 7 days of life, most commonly within 24-72 hours
It is a leading cause of neonatal sepsis, meningitis, and pneumonia, often acquired during labor and delivery.
Epidemiology:
GBS colonizes the lower genital tract of approximately 10-30% of pregnant women
While most neonates born to colonized mothers do not develop disease, early-onset infection occurs in about 0.5-1.5 per 1,000 live births
Prematurity, prolonged rupture of membranes, intrapartum fever, and chorioamnionitis are significant risk factors.
Clinical Significance:
GBS EOD is a medical emergency with high morbidity and mortality rates
Prompt recognition and treatment are crucial to improve outcomes and prevent long-term sequelae such as developmental delay, hearing impairment, and neurological deficits
Understanding prevention strategies through intrapartum antibiotic prophylaxis (IAP) is a cornerstone of obstetric and neonatal care.
Prevention
Intrapartum Prophylaxis Indications:
IAP is recommended for pregnant women who: have tested positive for GBS bacteriuria during the current pregnancy
have a history of a previous infant with invasive GBS disease
or have unknown GBS status at the onset of labor with any of the following risk factors: gestational age < 37 weeks, rupture of membranes ≥ 18 hours, intrapartum fever ≥ 38.0°C (100.4°F).
Gbs Screening:
Universal GBS screening of all pregnant women is recommended between 35 0/7 and 37 6/7 weeks of gestation using a rectovaginal swab
Cultures are the preferred method
rapid tests may be used in specific circumstances but should not replace culture if results are negative and risk factors are present.
Antibiotic Choices For Iap:
Penicillin G is the preferred agent, given intravenously at a dose of 5 million units for the initial dose, followed by 2.5-3 million units every 4 hours until delivery
For penicillin-allergic women without anaphylaxis risk, cefazolin (2 g IV for initial dose, then 1 g IV every 8 hours) is an alternative
For those with anaphylaxis risk, clindamycin (900 mg IV every 8 hours) or vancomycin (1 g IV every 12 hours) may be used, though resistance to clindamycin should be considered.
Duration Of Iap:
Adequate IAP requires administration of at least one dose of antibiotics at least 4 hours before delivery
Shorter intervals may be acceptable if the patient presents late in labor and IAP can be initiated.
Clinical Presentation
Symptoms:
Neonates may present with nonspecific signs of illness
Common symptoms include lethargy and poor feeding
Other signs can include respiratory distress (tachypnea, grunting, retractions), hypothermia or fever, irritability, vomiting, seizures, and hypotonia.
Signs:
Physical examination findings can include generalized edema (anasarca), jaundice, pallor, abdominal distension, and signs of shock (hypotension, poor perfusion)
Neurological signs may include a bulging fontanelle or nuchal rigidity if meningitis is present.
Disease Manifestations:
GBS EOD can manifest primarily as sepsis, pneumonia, or meningitis
These can occur in isolation or combination
Neonatal GBS meningitis is particularly concerning due to the high risk of long-term neurological sequelae.
Diagnostic Approach
History Taking:
Obtain a detailed maternal obstetric history including GBS screening status, any history of GBS colonization, intrapartum fever, duration of ruptured membranes, and any interventions
Neonatal history should focus on onset of symptoms, feeding patterns, and changes in activity.
Physical Examination:
A thorough physical examination is essential, focusing on vital signs, assessment for respiratory distress, signs of sepsis (e.g., perfusion, temperature instability), neurological status (e.g., alertness, tone, fontanelle), and presence of edema or jaundice.
Investigations:
Blood culture is mandatory for suspected sepsis
Cerebrospinal fluid (CSF) analysis with Gram stain and culture is crucial for suspected meningitis
Complete blood count (CBC) with differential, C-reactive protein (CRP), and chest X-ray (if respiratory symptoms are present) are also important
Urine culture may be considered but is less useful for EOD
Detection of GBS antigen in urine or vaginal fluid during pregnancy is not a substitute for culture.
Differential Diagnosis:
Differential diagnoses for neonatal sepsis include infections caused by other bacteria (e.g., E
coli, Staphylococcus aureus), viruses, and non-infectious causes of distress such as birth asphyxia, congenital anomalies, or metabolic disorders.
Management
Initial Management:
Prompt initiation of empirical broad-spectrum antibiotic therapy is critical for suspected GBS EOD
This should be started immediately after blood and CSF (if indicated) cultures are obtained, without waiting for results
Support of airway, breathing, and circulation (ABCs) is paramount.
Medical Management:
Empirical treatment for suspected GBS sepsis/meningitis in neonates typically involves a combination of penicillin G (or ampicillin) and an aminoglycoside (e.g., gentamicin) to provide coverage for Gram-positive and Gram-negative organisms
If GBS is confirmed, therapy is usually continued with penicillin G for 7-10 days for sepsis and 10-14 days for meningitis, depending on clinical response and CSF findings
Doses should be adjusted for renal function and prematurity
Dosing for penicillin G in EOD is typically 50,000 units/kg/dose IV every 6-12 hours for term neonates and every 12-24 hours for preterm neonates, depending on postnatal age.
Supportive Care:
Supportive care includes fluid management, nutritional support (enteral or parenteral), management of fever or hypothermia, oxygen therapy or mechanical ventilation if respiratory failure occurs, and anticonvulsant therapy if seizures are present
Close monitoring in a neonatal intensive care unit (NICU) is essential.
Complications
Early Complications:
Early complications include progression to severe sepsis, shock, disseminated intravascular coagulation (DIC), respiratory failure requiring mechanical ventilation, and neurological deterioration leading to seizures or coma.
Late Complications:
Long-term sequelae, particularly following GBS meningitis, can include developmental delay, cerebral palsy, hearing loss, visual impairment, and epilepsy
Recurrent infections are rare but possible.
Prevention Strategies:
Effective intrapartum antibiotic prophylaxis is the primary strategy to prevent GBS EOD
Timely recognition and prompt, appropriate treatment of suspected neonatal infection are crucial to minimize complication severity.
Prognosis
Factors Affecting Prognosis:
Prognosis is significantly influenced by gestational age at birth (preterm infants have worse outcomes), the specific manifestation of disease (meningitis carries a poorer prognosis than sepsis alone), the speed of diagnosis and initiation of treatment, and the presence of complications like shock or DIC.
Outcomes:
Mortality rates for GBS EOD have decreased with improved IAP strategies and neonatal care but remain significant, particularly in preterm infants
Survivors may experience significant neurodevelopmental impairments.
Follow Up:
Neonates who have survived GBS EOD, especially meningitis, require comprehensive neurodevelopmental follow-up
This includes regular assessments of cognitive function, motor skills, hearing, and vision, often extending into early childhood.
Key Points
Exam Focus:
Understand the indications for and limitations of intrapartum antibiotic prophylaxis for GBS
Know the typical clinical presentation, diagnostic workup, and initial management of suspected early-onset GBS disease
Be familiar with the recommended antibiotic regimens and durations for GBS sepsis and meningitis.
Clinical Pearls:
Always consider GBS in any neonate presenting with signs of sepsis, pneumonia, or meningitis, especially if there are risk factors such as prematurity or prolonged rupture of membranes
Don't delay antibiotic treatment while awaiting culture results in suspected cases
Remember that negative GBS screening does not entirely eliminate risk.
Common Mistakes:
Failure to administer adequate intrapartum prophylaxis in high-risk pregnancies
Delaying antibiotic administration in a symptomatic neonate
Inadequate antibiotic duration or dosage for confirmed GBS disease, particularly meningitis
Not pursuing appropriate neurodevelopmental follow-up for survivors of GBS meningitis.