Perinatal Infx

Question 1

Varicella-Zoster virus

Answer 1

Perinatal Infx
- DS, linear DNA genome
- Replicate in the nucleus
- Icosahedral, Enveloped, spherical to pleomorphic, Large
- latency in *sensory ganglia
- *Lytic replication
- *assembles Nucleocapsid inside the nucleus
Diseases
*Congenital varicella syndrome (infection in weeks 8 to 20)
a. Manifestations
i. Intrauterine growth restriction
ii. Cicatricial skin lesions
iii. Ocular defects
iv. Limb abnormalities
1. Hypoplasia of bone and muscle
v. CNS abnormalities
1. Cortical atrophy, seizures, and intellectual disability
b. Overall, the prognosis of infants born with CVS is poor.
*Infant zoster (due to maternal varicella after 25 weeks gestation)
*Neonatal varicella (due to maternal infection immediately before/after delivery)
a. Manifestations
i. Mild rash
ii. Disseminated varicella
1. Pneumonia, Hepatitis, Encephalitis, Liver failure, Thrombocytopenia
Postnatal varicella (respiratory droplets or direct contact)
Pathogenesis
1. Primary infection during pregnancy
TX
- acyclovir
Prevention
1. Before pregnancy
a. Live, attenuated vaccine (VariVAX)
2. During pregnancy or after birth
a. Varicella immunoglubulins (VariZIG)
3. Nosocomial/community infections
a. Isolation

Question 2

Herpes simplex virus

Answer 2

Perinatal Infx
- Double-stranded, linear DNA genome 
 - Replicate in the nucleus 
- Large Icosahedral, Enveloped, spherical to pleomorphic
- latency in *sensory ganglion cells 
- has *DNA polymerase
Diseases
1. Lesions after 1 week of life 
2. Three types of disease:
   a. *Skin, eye & mouth (SEM) lesions
   b. *CNS disease +/- SEM
   c. *Disseminated disease = sepsis
Pathogenesis
1. Usually a primary maternal HSV-2 infection acquired near time of delivery 
Tx
- Acyclovir
Prevention
1. No vaccine for HSV-1 or HSV-2
2. Safe sex practices
3. Cesarean section 
4. No direct contact with newborn if HSV lesions present

Question 3

Hepatitis B virus

Answer 3

Perinatal Infx
- *Partially DS, circular DNA genome
- Replicates in the nucleus
- Icosahedral, Enveloped, Small
- Uses *Reverse Transcriptase inside the nucleocapsid
Viral Proteins
i) S=surface protein (HBsAg) for binding, assembly & release
ii) C=precore/core region; core=HBcAg, forms nucleocapsid; precore = HBeAg, secreted into blood & likely an immune tolerogen; not packaged in virion
iii) P=polymerase Enzyme. converts the viral RNA to partial DS-DNA, inside the nucleocapsid
iv) X=HBx protein; transcriptional transactivator; may contribute to oncogenesis; not packaged in virion
Viral Particles
• “Dane particle” = Infectious viral particle, 42nm in diameter
• Filamentous = Subviral 20nm-wide filaments with variable length
• Spherical = Subviral spheres, 20nm diameter
Diseases
1. Neonatal period
a. *No clinical illness
2. 2-6 months old
a. *Mild, elevated liver enzymes
b. *Hepatitis
Pathogenesis
1. HBeAg may cross the placenta & induce immune tolerance in the fetus to a subsequent HBV infection
Transmission
1. Transmission during delivery
2. Exposure of infant’s mucous membranes to maternal secretions in the birth canal
3. Rarely transmitted in utero or by breastfeeding
5. Household contact in infancy or early childhood
Tx
1. Any antiviral treatment
Prevention
1. Recombinant vaccine (HBsAg)
2. Screening pregnant women in 1st trimester for HBsAg, anti-HBc, anti-HBs
3. Hepatitis B immune globulin (HBIG) plus HBV vaccine for infants born to HBsAg+ mothers

Question 4

Streptococcus agalactiae

Group B Streptococcus

Answer 4

Perinatal Infx
i) Gr+ cocci in chains or diplococcal
- facultative anaerobes
ii) Only species with *Group B Lancefield antigen 
• Catalase-negative
• β-hemolytic 
• Bacitracin-resistance
• Hippurate-positive 
• *CAMP-positive 
Virulence
• *Adhesive pili 
• **Polysaccharide capsule
Disease
1. Early-onset
   a. * 90 days old
   b. *bacteremia w/out a focus or meningitis
4. mortality rate is

Question 5

Neisseria gonorrhoeae

Answer 5

Perinatal Infx
- Gr- diplococci
- obligate human pathogen
- fragile
- oxidase +
- catalase +
Virulence
- *Opa  
- *pili
- *LOS
- *IgA1 protease
- *outer-membrane blebbing
Disease
1. *Ophthalmia neonatorum 
2. *Localized infection of other muscosal surfaces (pharynx, vagina, urethra, and anus)
3. *Disseminated disease (sepsis, arthritis, or meningitis)
Transmission
1. *Passage through birth canal
2. *Rupture of the membranes
Prevention
1. Erythromycin ophthalmic ointment prophylaxis 
2. Screening & treating pregnant women for gonorrhea

Question 6

Chlamydia trachomatis

Answer 6

Perinatal Infx
- small Gr-
- *obligate intracellular parasite
- ‘lack peptidoglycan’
- *elementary body - metabolically inactive, infix, *extracellular form
- *reticulate body - actively *replicating, noninfx
Disease
1. *Inclusion conjunctivitis
a. Presents between 5 to 14 days after delivery
2. Neonatal chlamydial pneumonia
a. Presents between 4 and 12 weeks after delivery
Transmission
- usually due to exposure during vaginal birth
Tx
a. *Oral erythromycin
Prevention
a. *Screening pregnant women & treating those with a chlamydial infection with antibiotics
b. *Neonatal ocular prophylaxis NOT effective to prevent chlamydial conjunctivitis