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What are the primary capsular polysaccharide types of Group B streptococci that account for most cases in infants?
What are the primary capsular polysaccharide types of Group B streptococci that account for most cases in infants?
Types Ia, Ib, II, III, and V account for approximately 95% of cases in infants.
What is the relevance of type III capsular polysaccharide in Group B streptococci infections in infants?
What is the relevance of type III capsular polysaccharide in Group B streptococci infections in infants?
Type III is the predominant cause of early- and late-onset meningitis in infants.
What was the incidence rate of early-onset Group B streptococcal disease before the introduction of maternal intrapartum antimicrobial prophylaxis?
What was the incidence rate of early-onset Group B streptococcal disease before the introduction of maternal intrapartum antimicrobial prophylaxis?
The incidence was 1 to 4 cases per 1000 live births.
How has the incidence of early-onset Group B streptococcal disease changed since the implementation of maternal prophylaxis?
How has the incidence of early-onset Group B streptococcal disease changed since the implementation of maternal prophylaxis?
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What factors contribute to higher case-fatality ratios in infants with Group B streptococcal infection?
What factors contribute to higher case-fatality ratios in infants with Group B streptococcal infection?
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What are the transmission routes for Group B streptococci from mother to infant?
What are the transmission routes for Group B streptococci from mother to infant?
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What percentage of pregnant women are typically colonized by Group B streptococci?
What percentage of pregnant women are typically colonized by Group B streptococci?
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What challenges exist concerning the incidence of late-onset Group B streptococcal disease?
What challenges exist concerning the incidence of late-onset Group B streptococcal disease?
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Which populations are at an increased risk for sporadic, invasive GAS disease?
Which populations are at an increased risk for sporadic, invasive GAS disease?
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Why is targeted chemoprophylaxis recommended for certain high-risk populations?
Why is targeted chemoprophylaxis recommended for certain high-risk populations?
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What is the rationale for not recommending chemoprophylaxis in schools or childcare facilities?
What is the rationale for not recommending chemoprophylaxis in schools or childcare facilities?
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Identify two specific medical conditions considered as risk factors for invasive GAS disease.
Identify two specific medical conditions considered as risk factors for invasive GAS disease.
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In relation to GAS disease, what age group is particularly highlighted for targeted interventions?
In relation to GAS disease, what age group is particularly highlighted for targeted interventions?
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What are the key virulence factors associated with Group B Streptococcus (GBS) infections?
What are the key virulence factors associated with Group B Streptococcus (GBS) infections?
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How does the epidemiology of GBS differ between pregnant women and non-pregnant populations?
How does the epidemiology of GBS differ between pregnant women and non-pregnant populations?
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What role does maternal intrapartum prophylaxis play in preventing GBS infections in newborns?
What role does maternal intrapartum prophylaxis play in preventing GBS infections in newborns?
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Identify the main risk factors for GBS infection among pregnant women.
Identify the main risk factors for GBS infection among pregnant women.
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Explain the transmission routes of Group B Streptococcus in a healthcare setting.
Explain the transmission routes of Group B Streptococcus in a healthcare setting.
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Study Notes
Group B Streptococcal Infections
- Group B streptococci (GBS) are a major cause of perinatal infections, including bacteremia, endometritis, intra-amniotic infection, and urinary tract infections in women during pregnancy and postpartum, and systemic/focal infections in neonates and infants.
Clinical Manifestations
- Early-onset disease: typically within 24 hours of life, characterized by systemic infection, respiratory distress, apnea, shock, pneumonia, and sometimes meningitis.
- Late-onset disease: typically at 3-4 weeks of age, often manifests as occult bacteremia or meningitis, also osteomyelitis, septic arthritis, necrotizing fasciitis, pneumonia, adenitis, and cellulitis.
Etiology
- Gram-positive, aerobic diplococci, producing beta hemolysis on 5% sheep blood agar.
- Classified into 10 types (Ia, Ib, and II-IX); types Ia, Ib, II, III, and V account for ~95% of infant cases in the US.
- Capsular polysaccharides and pilus-like structures are important virulence factors.
Epidemiology
- Common inhabitants of the human gastrointestinal and genitourinary tracts.
- Colonization rate in pregnant women ranges from 15-35%.
- Early-onset incidence was 1-4 cases per 1000 live births, reduced to ~0.25 cases per 1000 live births post-intrapartum antimicrobial prophylaxis.
- Increased risk for preterm infants, infants with ruptured membranes (>18 hours), mothers with high genital GBS inoculum, intrapartum fever, previous infant with invasive GBS disease, and low/undetectable maternal antibody levels.
- Black infants have higher incidence of both early- and late-onset disease than white infants.
Diagnosis
- Gram stain of body fluids shows gram-positive cocci in pairs or short chains.
- Culture of blood, CSF, or affected sites is necessary for confirmation.
- Multiplex polymerase chain reaction assay can directly detect GBS in CSF.
- Culture screening at 35-37 weeks gestation in pregnant women is recommended to identify GBS colonization.
Treatment
- For early-onset GBS infection in newborns, ampicillin plus an aminoglycoside is the initial treatment of choice.
- Late-onset meningitis: ampicillin/aminoglycoside, cefotaxime, or vancomycin/ceftriaxone for infants >2 months.
- For infants with meningitis, the recommended dose of penicillin G or ampicillin is adjusted for age (<7 days vs >7 days).
- Intrapartum chemoprophylaxis is recommended for certain high-risk pregnant women to prevent neonatal GBS disease.
Control Measures
- Pregnant women should undergo GBS culture screening.
- Intrapartum antibiotic prophylaxis is recommended in certain high-risk scenarios.
- Chemoprophylaxis is not recommended in schools or child care settings due to low risk of secondary cases and minimal risk of invasive GBS infections in children.
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Description
Explore the clinical manifestations and etiology of Group B Streptococcal infections, particularly in perinatal contexts. This quiz covers early and late-onset diseases, their symptoms, and the types of bacteria involved. Test your understanding of this critical area of infectious disease in obstetrics and pediatrics.
