Group B Streptococcal Infections
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Questions and Answers

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?

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?

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?

<p>It has decreased by approximately 80% to an estimated 0.25 cases per 1000 live births.</p> Signup and view all the answers

What factors contribute to higher case-fatality ratios in infants with Group B streptococcal infection?

<p>The case-fatality ratio is higher in preterm neonates, estimated at 20% for early-onset disease.</p> Signup and view all the answers

What are the transmission routes for Group B streptococci from mother to infant?

<p>Transmission occurs shortly before or during delivery and can also happen through person-to-person contact after birth.</p> Signup and view all the answers

What percentage of pregnant women are typically colonized by Group B streptococci?

<p>Colonization rates in pregnant women range from 15% to 35%.</p> Signup and view all the answers

What challenges exist concerning the incidence of late-onset Group B streptococcal disease?

<p>The incidence of late-onset disease has nearly equaled that of early-onset disease despite prophylaxis.</p> Signup and view all the answers

Which populations are at an increased risk for sporadic, invasive GAS disease?

<p>People with HIV infection and individuals aged 65 years and older are at increased risk.</p> Signup and view all the answers

Why is targeted chemoprophylaxis recommended for certain high-risk populations?

<p>It is recommended to reduce the risk of death and severe illness associated with invasive GAS disease.</p> Signup and view all the answers

What is the rationale for not recommending chemoprophylaxis in schools or childcare facilities?

<p>The rarity of secondary cases and low risk of invasive GAS infections in children support this decision.</p> Signup and view all the answers

Identify two specific medical conditions considered as risk factors for invasive GAS disease.

<p>HIV infection and diabetes mellitus are two specific risk factors.</p> Signup and view all the answers

In relation to GAS disease, what age group is particularly highlighted for targeted interventions?

<p>Individuals aged 65 years and older are particularly highlighted for interventions.</p> Signup and view all the answers

What are the key virulence factors associated with Group B Streptococcus (GBS) infections?

<p>The key virulence factors associated with GBS infections include the ability to evade host immune responses and the production of polysaccharide capsules.</p> Signup and view all the answers

How does the epidemiology of GBS differ between pregnant women and non-pregnant populations?

<p>GBS is a common colonizer in pregnant women but poses a significant risk for neonatal infections, whereas it is typically less pathogenic in non-pregnant populations.</p> Signup and view all the answers

What role does maternal intrapartum prophylaxis play in preventing GBS infections in newborns?

<p>Maternal intrapartum prophylaxis involves administering antibiotics during labor to reduce the risk of vertical transmission of GBS to the newborn.</p> Signup and view all the answers

Identify the main risk factors for GBS infection among pregnant women.

<p>Main risk factors for GBS infection in pregnant women include a previous baby with GBS disease, prolonged rupture of membranes, and preterm labor.</p> Signup and view all the answers

Explain the transmission routes of Group B Streptococcus in a healthcare setting.

<p>Transmission of GBS in a healthcare setting commonly occurs through direct contact during childbirth or via vertical transmission from mother to infant.</p> Signup and view all the answers

Flashcards

GAS disease risk in certain populations

Increased risk of invasive GAS disease exists in high-risk groups like people with HIV, those aged 65 and older, and others with specific illnesses (e.g., varicella, diabetes mellitus).

Chemoprophylaxis in household contacts

Doctors might recommend preventive medicine (chemoprophylaxis) to household contacts of high-risk individuals (e.g., age 65+) to reduce GAS infection risk.

Chemoprophylaxis for children

Chemoprophylaxis isn't usually recommended in schools or childcare settings due to low risk in children.

High-risk Populations (GAS)

People with compromised immune systems, the elderly (65+), and those with specific conditions (e.g., HIV, varicella, diabetes mellitus) are more susceptible to severe GAS infections.

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Secondary cases of GAS

Secondary cases of invasive GAS infections are rare.

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Household contact risk

People living with someone who has severe invasive GAS disease (like STSS) have a slightly higher risk of getting it themselves.

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Routine GAS testing for contacts?

No, routine testing for GAS in household contacts isn't usually recommended because the risk isn't high enough.

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Chemoprophylaxis for contacts

There's no clear-cut effective treatment to prevent GAS in all household contacts, so routine prevention medicine isn't common practice.

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Severe invasive GAS risk

Household contacts of people with severe invasive GAS disease might have a higher risk of getting it themselves.

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STSS

STSS stands for 'Streptococcal Toxic Shock Syndrome', a serious complication of GAS infection.

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Group B Strep Types

There are 10 types, categorized by capsular polysaccharides. Types Ia, Ib, II, III, and V are the most common in infants, while type IV affects adults.

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Virulence Factors in Group B Strep

Capsular polysaccharides and pilus-like structures are important for causing disease (virulence factors) and are potential targets for vaccines.

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Where is Group B Strep Found?

Group B Strep commonly resides in the human digestive system (gastrointestinal tract) and reproductive system (genitourinary tract).

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Group B Strep Colonization in Pregnant Women

From 15% to 35% of pregnant women carry Group B Strep, which can come and go (intermittent) or be there constantly.

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Early-Onset GBS Disease

This occurs in infants within the first 7 days of life and is often caused by Group B Strep.

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Late-Onset GBS Disease

This happens after 7 days of life, but within 3 months, and is often caused by Group B Strep.

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GBS Disease Transmission

Babies usually get GBS from their mothers during childbirth, but can spread person-to-person after delivery.

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Group B Strep Control Measures

Preventing early-onset GBS involves giving antibiotics to mothers during labor (intrapartum chemoprophylaxis).

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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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Group B Streptococcal Infections PDF

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.

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