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What are the 3 routes of infection for newborns?
- 1) Congenital, across the placenta
- 2) Prenatal, passage down birth canal
- 3) Post-natal, milkd, blood, saliva, contact
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What are the 3 bacterial infections involved in obstetric and perinatal infections?
- 1) Group B Streptococcus spp. (S. agalactiae)
- 2) E. coli K1
- 3) L. monocytogenes
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S. agalactiae (Group B Streptococcus)
Virulence factors? Pathogenesis? Clinical ID and Diagnosis?
- Virulence factors
- Adherence
- Polysaccharide capsule
- Invasion
- Beta-hemolysin
- Pathogenesis
- Occurs by exposure to organism - rupture/damage to utero membranes, contamination via birth canal
- Increased inoculum
- Mucous membranes are targeted for infection
- Survive in the bloodstream
- Early and late onset syndromes
- Clinical ID and Diagnosis
- Gram+, catalase (-), beta-hemolytic, diplococci or short chains in liquid media
- Normal flora
- Major cause in bacterial meningitis
- EOD first 5 days of birth, along with septicemia, pneumonia or meningitis
- LOD 3-8 weeks after birth
- CSF or blood cultures (+)
- Management S. agalactiae infection via intrapartum prophylaxis
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Compare and contrast the Early-onset disease (EOD) and Late-onset disease (LOD) of S. agalactiae infection in newborns.
- EOD
- Occurs within forst week, usually within first 24 hours
- Results in meningitis, pneumonia and bacteremia
- Risk factors include: mother is positive for S. agalactiae, low birth weight, low maternal anti-capsular IgG antibody
- Obstetric risk factors: intrapartum fever, rupture of membranes before labor, and prolonged labor and rupture of membranes
- LOD
- Occurs within 7 or more days of birth
- Results in meningitis
- Risk factors: not well understood, nosocomial and horizontal transmission may be involved
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What is the best prevention and/or treatment for Early-onset disease of Group B Streptococcal (S. agalactiae) infection?
No reliable antibiotic treatment is available, "blind" treatment of sick baby who has risk factors
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What is the best prevention and/or treatment for Late-onset disease of Group B Streptococcal (S. agalactiae) infection?
Good hygiene practices in nurseries, don't allow mother to hold or handle other babies
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E. coli K1
Virulence factors? Pathogenesis? Clinical ID and Diagnosis?
- Virulence factors
- K1 polysialic capsule - resistant to killing by neutrophils and normal serum, aids in survival in blood and CSF
- Invasins - IbeA anf IbeB, assist crossing of blood-brain-barrier
- Type O antigen on LPS
- Pathogenesis
- Vagial E. coli colonizes the infant via ruptured amniotic membranes or during delivery
- Prematurity, low birth weight and prolonged rupture of membranes may contribute
- Presents as septicemis first 2 days after birth
- Clinical ID and Diagnosis
- Common cause of neonatal meningitis
- Gram- bacillus, major inhabitant of the large intestine
- Symptoms are respiratory distress, fever, poor feeding, abdominal distention
- CSF and blood culture +
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Listeria monocytogenes
Virulence factors? Pathogenesis? Clinical ID and Diagnosis?
- Virulence factors
- Intracellular lifestyle
- Internalins - cell invasion
- Listeriolysin O - escape from host vacuoles
- ActA - allows for cell-to-cell spread via host-derived actin filaments
- Pathogenesis
- Causes congenital,perinatal and post-natal infections
- Primarily food-borne
- Immunocompromised patients at risk
- Immunity is cell-mediated
- Tropism for fetus and placenta
- Can lead to neonatal meningitis
- Clinical ID and Diagnosis
- Gram+ rod, can grow in fridge (4-41 degrees Celsius)
- Ubiquitous
- Fecal carriers are asymptomatic
- Blood, CSF, amniotic fluid and UG tract secretions cultures +
- PCR
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What is the most common parasite involved in obstetric and perinatal infections?
T. gondii
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Toxoplasma gondii
Virulence factors? Pathogenesis? Clinical ID and Diagnosis?
- Virulence factors
- Invasion - actin-based motor
- Modification of host cell vacuole
- Pathogenesis
- Ingestion of uncooked meat, food or water contaminated cat feces, exposure while cleaning litter box
- Blood transfusions
- From mother to fetus
- Once oocysts are ingested, the sporozoites are released and enter macrophages
- Congenital infection can result in spontaneous abortion and still birth
- Live born children may have: microencephaly, hydrocephaly, psychomotor disturbances and convulsions
- Chorioretinitis is common
- Clinical ID and Diagnosis
- Come in 3 forms: oocyst, tachyzoites, tissue cyst bradyzoite
- Acute infection
- Must collect specimen early for detection
- Very high IgG titer
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What are the 4 tissues where T. gondii most commonly form cysts?
- 1) skeletal muscle
- 2) myocardium
- 3) brain
- 4) eyes
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