Group B Strep Disease: Symptoms, Types, Causes and Treatment

Group B Streptococcus (GBS) is a common bacterium that can cause a range of infections in newborns, pregnant women, and adults with underlying health conditions. While many people carry GBS without symptoms, the disease can be life-threatening, especially for newborns and immunocompromised adults. This article provides a comprehensive overview of GBS disease—focusing on its symptoms, types, causes, and treatment—using the latest research and clinical insights.

Symptoms of Group B Strep Disease

Group B Strep disease presents with a variety of symptoms, depending on the age and health of the affected individual. Recognizing these symptoms early is crucial, especially in newborns, where rapid progression can lead to severe complications.

Patient	Main Symptoms	Severity	Source(s)
Newborns	Apnea, shock, pneumonia, sepsis, meningitis	Severe, rapid onset	1 2 6
Pregnant Women	Urinary tract infection, amnionitis, endometritis	Mild to severe	2 4 14
Adults	Bacteremia, soft tissue infection, pneumonia, meningitis, urosepsis	Severe, especially with comorbidities	7 10

Table 1: Key Symptoms

Symptoms in Newborns

Newborns are the most vulnerable group. GBS infection in infants can be divided into early-onset disease (EOD) and late-onset disease (LOD):

• Early-Onset Disease (EOD): Occurs within the first week of life, usually within 24–72 hours. Symptoms include:

  • Apnea (pauses in breathing)
  • Shock
  • Lethargy or irritability
  • Poor feeding
  • Pneumonia and sepsis
  • Meningitis may occur but is more common in LOD 1 2 6

• Late-Onset Disease (LOD): Appears between 1 week and 3 months after birth. Symptoms are often related to:

  • Meningitis (present in over half of LOD cases)
  • Fever
  • Poor feeding
  • Lethargy
  • Seizures 2 6 9

Symptoms in Pregnant Women

GBS commonly colonizes the vaginal or rectal areas without symptoms. When symptomatic, GBS can cause:

• Urinary tract infections (UTIs)
• Amnionitis (infection of the amniotic fluid)
• Endometritis (infection of the uterine lining) Symptoms may include fever, abdominal pain, and urinary frequency or burning. In rare cases, the infection can cause sepsis 2 4 14.

Symptoms in Nonpregnant Adults

While less common, GBS infection in adults can be serious, especially in those with chronic illnesses. Symptoms include:

• Bacteremia (bloodstream infection)
• Skin and soft tissue infections (cellulitis, abscesses)
• Pneumonia
• Urosepsis (UTI leading to sepsis)
• Meningitis
• Peritonitis These infections can be severe and are associated with a high mortality rate in older or immunocompromised adults 7 10.

Types of Group B Strep Disease

GBS disease manifests in several clinical forms, often categorized by onset and affected population. Each type has distinct features and implications for prevention and treatment.

Type	Key Features	Most Affected Group	Source(s)
Early-Onset Disease (EOD)	<7 days old, sepsis/pneumonia, rapid onset	Newborns	2 3 6 11
Late-Onset Disease (LOD)	7–89 days old, meningitis/sepsis	Newborns	2 3 6 9
Adult Invasive Disease	Bacteremia, SSTI, pneumonia, urinary tract	Adults	7 10
Maternal Disease	UTI, chorioamnionitis, endometritis	Pregnant women	2 14

Table 2: Types of Group B Strep Disease

Early-Onset Disease (EOD)

• Timing: First week of life, usually within 24–72 hours
• Manifestations: Sepsis, pneumonia, sometimes meningitis
• Transmission: Vertical—mother to baby during labor/delivery
• Serotypes: All serotypes, especially Ia, II, III, and V 2 3 6 11

Late-Onset Disease (LOD)

• Timing: 7 days to 3 months post-birth (can be up to 6 months)
• Manifestations: Meningitis is most common, along with sepsis and pneumonia
• Transmission: Can be vertical, but also horizontal (hospital/community acquired, breast milk)
• Serotypes: Mostly type III, with hypervirulent CC17 strains predominating 2 3 6 9

Adult Invasive Disease

• Population: Nonpregnant adults, especially those >60 years or with chronic diseases
• Manifestations: Bacteremia, skin and soft tissue infections, urosepsis, pneumonia, meningitis
• Prognosis: High mortality in elderly/immunocompromised 7 10

Maternal GBS Disease

• When: During pregnancy, at delivery, or postpartum
• Manifestations: UTIs (sometimes asymptomatic), chorioamnionitis, endometritis, sepsis
• Risks: Can lead to preterm birth or transmission to neonate 2 14

Causes of Group B Strep Disease

Understanding what causes GBS disease helps in both prevention and treatment. The disease arises when the typically harmless colonization of GBS becomes invasive, often triggered by specific risk factors.

Cause	Description	Affected Populations	Source(s)
Colonization	Asymptomatic vaginal/rectal carriage	Pregnant women, adults	2 8 14
Vertical Transmission	Mother to baby during labor/delivery	Newborns	2 6 11
Horizontal Transmission	Hospital/community, breast milk	Newborns, adults	6 9
Host Factors	Prematurity, immunodeficiency, chronic illness	Newborns, adults	6 7 9

Table 3: Causes and Risk Factors for GBS Disease

Colonization and Transmission

• GBS colonizes the gastrointestinal and genitourinary tracts of 10-30% of pregnant women, usually without symptoms 2 8 14.
• Vertical transmission occurs during labor or rupture of membranes, when GBS passes from mother to baby. Prolonged rupture (>12 hrs), maternal fever, and GBS bacteriuria increase risk 1 2 6 11.
• Horizontal transmission can occur postpartum from caregivers or hospital environment, or via breast milk 6 9.

Host Risk Factors

Certain factors increase the likelihood that GBS colonization will progress to invasive disease:

• For newborns:

  • Prematurity or low birthweight
  • Prolonged rupture of membranes
  • Maternal GBS colonization or infection
  • Maternal fever during labor
  • Young maternal age
  • Black ethnicity 6 9

• For adults:

  • Diabetes mellitus
  • Cancer
  • Immunosuppression (e.g., HIV)
  • Advanced age (>65)
  • Chronic diseases 7

Bacterial Factors

• Serotypes and Virulence: GBS has several serotypes; type III (especially CC17) is linked to LOD and meningitis in neonates. Certain strains have evolved increased virulence and antibiotic resistance 3 5 6 8.
• Molecular Mechanisms: GBS expresses factors that allow it to evade immune detection and invade tissues, leading to severe disease 8.

Treatment of Group B Strep Disease

Timely and appropriate treatment is crucial for GBS infections. Management strategies vary according to patient population, disease type, and risk of antibiotic resistance.

Approach	Details	Patient Group	Source(s)
Intrapartum Antibiotic Prophylaxis (IAP)	IV penicillin/ampicillin during labor	Pregnant women (to prevent EOD)	11 12 13 15
Empiric Antibiotic Therapy	IV penicillin, ampicillin, or cephalosporins	Newborns/adults with confirmed infection	4 7
Management of Bacteriuria	Treat ≥100,000 CFU/mL in pregnancy; IAP at delivery	Pregnant women	14
Alternative Antibiotics	For penicillin allergy: clindamycin, erythromycin	Allergic patients	4

Table 4: GBS Disease Treatment Strategies

Intrapartum Antibiotic Prophylaxis (IAP)

• Goal: Prevent early-onset GBS disease in newborns by reducing vertical transmission from mother to baby.
• Who Gets IAP: Women with GBS colonization, GBS bacteriuria during pregnancy, previous baby with GBS disease, or risk factors (e.g., preterm labor, fever, prolonged rupture of membranes) 11 12 13 14 15.
• Drugs Used: IV penicillin G or ampicillin; alternatives for allergic women include clindamycin or erythromycin (if sensitive) 4 14.
• Effectiveness: IAP dramatically reduces EOD, but not LOD, and there are ongoing debates about the optimal strategy due to potential for antibiotic resistance and rare adverse reactions 12 13 15.

Treatment of Established GBS Disease

• Neonates: Empiric IV antibiotics (penicillin or ampicillin, often with gentamicin) until GBS is ruled out or confirmed.
• Adults: IV penicillin G or ampicillin for confirmed cases; cephalosporins may be used. For penicillin-allergic patients, clindamycin or erythromycin (if susceptible) 4 7.

Management of GBS Bacteriuria in Pregnancy

• Significance: Any GBS bacteriuria (even at low colony counts) identifies a high-risk pregnancy.
• Management: Treat significant bacteriuria (>100,000 CFU/mL) during pregnancy and provide IAP at delivery, regardless of colony count 14.
• No need to re-screen women with documented GBS bacteriuria—they are presumed colonized 14.

Resistance and Future Directions

• GBS remains sensitive to penicillin and ampicillin, but resistance to tetracycline is high; resistance to clindamycin and erythromycin is low but rising 4 5.
• Ongoing research into GBS vaccines and preventive strategies, especially for LOD and adult disease 5 7 8.

Conclusion

Group B Streptococcus remains a significant cause of neonatal and adult infections, with severe outcomes if not recognized and treated promptly. While preventive strategies like intrapartum antibiotic prophylaxis have greatly reduced early-onset disease in newborns, challenges persist in preventing late-onset and adult infections.

Key Takeaways:

• Symptoms vary by age: Newborns present with sepsis, pneumonia, or meningitis; adults may show bacteremia or soft tissue infections.
• Types: Early- and late-onset disease in neonates, invasive disease in adults, and maternal infections.
• Causes: Colonization leading to infection, often triggered by vertical or horizontal transmission and risk factors like prematurity, immunodeficiency, or chronic illness.
• Treatment: Intrapartum antibiotics for at-risk mothers, empiric IV antibiotics for infected individuals, and targeted management for GBS bacteriuria in pregnancy.
• Prevention: Screening and risk-based strategies are crucial for reducing neonatal disease.

Ongoing vigilance, continued research into vaccines, and judicious antibiotic use remain essential for managing GBS disease across all populations.