Group B Streptococcus infection - Symptoms, Causes, Treatment & Prevention

Overview

Group B Streptococcus (GBS), also known as Streptococcus agalactiae, is a gram‑positive bacterium that normally lives in the gastrointestinal and genitourinary tracts of healthy adults. While most carriers never develop disease, GBS can cause serious infections when it spreads to sterile sites such as the bloodstream, meninges, or urinary tract.

GBS is best known for its impact on newborns, but it also affects pregnant women, the elderly, and adults with chronic medical conditions. In the United States, an estimated 25 % of pregnant women are colonized with GBS, and about 1 – 2 per 1,000 live births develop early‑onset disease (CDC, 2023). In adults, invasive GBS infections account for roughly 5 % of all bacteremia cases** and have a mortality rate of 10–20 % if not treated promptly.

Symptoms

Symptoms vary widely depending on the site of infection and the age group affected.

Neonates (0‑90 days)

• Early‑onset disease (≤7 days) – respiratory distress, grunting, apnea, fever or hypothermia, lethargy, poor feeding.
• Late‑onset disease (8‑90 days) – fever, irritability, vomiting, meningitis signs (bulging fontanelle, seizures), joint swelling.

Prenatal (Pregnant women)

• Asymptomatic colonization (most common)
• Urinary tract infection: dysuria, urgency, suprapubic pain.
• Chorioamnionitis: fever, uterine tenderness, foul‑smelling amniotic fluid.

Adults

• Skin & soft‑tissue infection: redness, warmth, swelling, pain, sometimes abscess formation.
• Invasive disease (bacteremia, meningitis, pneumonia): fever, chills, rapid heart rate, shortness of breath, headache, confusion, neck stiffness.
• Urinary tract infection: burning on urination, frequency, flank pain.
• Endocarditis: new heart murmur, fatigue, night sweats, unexplained weight loss.

Causes and Risk Factors

GBS infection results from the bacterium breaching normal barriers (skin, mucosa, or placental membranes) and entering sterile body sites.

Primary Causes

• Colonization of the vagina or rectum in pregnant women.
• Breaks in skin integrity (wounds, surgical sites, catheters).
• Transmission during childbirth – the baby passes through a colonized birth canal.

Risk Factors

• Pregnancy: especially >35 weeks gestation.
• Previous infant with GBS disease.
• Prolonged rupture of membranes (>18 h).
• Maternal fever during labor.
• Pre‑existing medical conditions: diabetes, obesity, liver disease, HIV/AIDS, malignancy.
• Advanced age (>65 y) and immunosuppression.
• Recent invasive procedures or indwelling devices (e.g., urinary catheters).

Diagnosis

Accurate diagnosis hinges on obtaining appropriate specimens before antibiotics are started.

Testing in Pregnant Women

• Universal prenatal screening: Vaginal‑rectal swab at 35–37 weeks gestation. Cultures grow GBS on selective media; results are reported as positive/negative.
• Rapid PCR assays provide results within hours and have >95 % sensitivity (CDC, 2022).

Neonatal Testing

• Blood cultures (gold standard) for suspected sepsis.
• CSF analysis + culture if meningitis is suspected.
• Chest X‑ray for pneumonia.

Adult Testing

• Blood cultures for fever or sepsis.
• Wound or abscess aspiration for Gram stain and culture.
• Urine culture if urinary symptoms present.
• Echocardiography when endocarditis is suspected.

Treatment Options

Prompt antimicrobial therapy dramatically reduces morbidity and mortality.

First‑Line Antibiotics

• Prenatal colonization (no active infection): Intrapartum penicillin G 5 million units IV every 4 h until delivery. For penicillin‑allergic patients, cefazolin or clindamycin (if susceptibility confirmed) is used.
• Neonatal early‑onset disease: Ampicillin + an aminoglycoside (gentamicin) for 10–14 days.
• Late‑onset disease: Usually a 10‑day course of a third‑generation cephalosporin (e.g., cefotaxime) plus vancomycin if resistance suspected.
• Adult invasive infection: Penicillin G or ampicillin for 2 weeks; for meningitis, extend to 4 weeks. Vancomycin is added if the isolate is resistant to β‑lactams.

Adjunctive Measures

• Supportive care (IV fluids, oxygen, antipyretics).
• Surgical drainage of abscesses or debridement of necrotic tissue.
• Removal of infected catheters or prosthetic material.

Lifestyle & Supportive Strategies

• Maintain good skin hygiene; keep wounds clean and covered.
• Stay up‑to‑date with vaccinations (influenza, pneumococcal) to reduce secondary infections.

Living with Group B Streptococcus Infection

For individuals who have had an invasive GBS infection, long‑term management focuses on preventing recurrence and monitoring for late complications.

Daily Management Tips

• Medication adherence: Complete the full antibiotic course even if you feel better.
• Wound care: Clean any cuts with mild soap, apply sterile dressings, and watch for redness or drainage.
• Hydration & nutrition: Adequate fluid intake supports kidney function and immune response.
• Follow‑up appointments: Repeat blood cultures are often ordered 48 h after therapy begins to confirm clearance.
• Monitoring for late sequelae: Persistent fatigue, joint pain, or new fevers should be reported.

Special Considerations for Pregnant Women

• Attend all prenatal visits; the GBS screening is usually performed between 35–37 weeks.
• If you were colonized in a previous pregnancy, your obstetrician may repeat screening earlier.
• Discuss any history of penicillin allergy well before labor to arrange appropriate intrapartum prophylaxis.

Prevention

• Universal prenatal screening: Reduces early‑onset neonatal disease by ~80 % (CDC, 2023).
• Intrapartum antibiotic prophylaxis for colonized mothers.
• Good hand hygiene for caregivers and healthcare workers.
• Prompt treatment of maternal urinary or skin infections during pregnancy.
• Avoid unnecessary prolonged rupture of membranes; consider early induction if risk factors present.
• For adults with chronic disease, regular medical check‑ups and early treatment of skin breakdowns.

Complications

If untreated or delayed, GBS can lead to severe, life‑threatening conditions.

• Neonates: Sepsis, meningitis, pneumonia, permanent neurological impairment, or death.
• Pregnant women: Chorioamnionitis, preterm labor, uterine rupture.
• Adults: Endocarditis, osteomyelitis, septic arthritis, urinary sepsis, meningitis.
• Long‑term organ damage (e.g., kidney failure after overwhelming sepsis) in high‑risk patients.

When to Seek Emergency Care

References

• Centers for Disease Control and Prevention. Group B Streptococcus (GBS) Disease. Updated 2023.
• Mayo Clinic. Group B Strep (GBS) Infection. Accessed April 2026.
• National Institutes of Health. Invasive Group B Streptococcal Disease in Adults. Clinical Infectious Diseases, 2022.
• World Health Organization. Fact Sheet: Group B Streptococcus. 2022.
• Cleveland Clinic. Group B Strep (GBS) in Pregnancy. Reviewed 2024.