Obstetric and Perinatal Infections (Dr. Neely)

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davis.tiff
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168297
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Obstetric and Perinatal Infections (Dr. Neely)
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2012-08-31 14:21:53
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MICROBIOLOGY INFECTIOUS DISEASES
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MICRO/ID EXAM III
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  1. 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
  2. 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
  3. 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
  4. 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
  5. 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
  6. 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
  7. 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 +
  8. 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
  9. What is the most common parasite involved in obstetric and perinatal infections?
    T. gondii
  10. 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
  11. 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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