Neonatal Teaching: Neonatal Infection Flashcards
Perinatal infection
Etiology:
1. Bacterial
2. Viral
3. Protozoal
4. Fungal
5. Parasitic
Route of transmission:
1. ***Intrauterine (Bloodborne via placenta)
- Syphilis
- CMV
- Toxoplasma
- ***Ascending
- Bacterial
- HSV - ***Direct contact
- HSV
- HBV
- HIV
- HPV
Acute vs Chronic infection:
1. Acute infection
- **Bacterial mostly
- In-utero fetal demise
- **Perinatal infection
- ***Preterm delivery
- Chronic infection
- **Viral mostly
- In-utero fetal demise
- **IUGR
- **Congenital malformations
- **Chronic organ dysfunction
- ***TORCH syndrome
TORCH syndrome
- Toxoplasmosis
- Others
- Rubella
- CMV
- HSV
Common features (細頭肚大有紅點):
1. **Hepatosplenomegaly
2. **Microcephaly
3. **Petechiae
4. **IUGR
Others:
- Varicella
- HIV-1
- Treponema pallidum (Syphilis)
- Coxsackievirus
- Human parvovirus B19
- Mycobacterium tuberculosis
- etc.
Syphilis
Maternal syphilis:
- STD
- Incubation period: 10-90 days
- Primary / Secondary / Tertiary
VDRL (Treponemal non-specific test):
- Primary: 80% +
- Secondary: 100% +
- Becomes **non-reactive if treatment effective
- **False positive in pregnancy
FTA-ABS (Treponemal specific test):
- Primary: 85%
- Secondary: 100%
- Titre ***persists for life
Treatment for maternal syphilis:
- Goal: Reduces chance of **Congenital syphilis
- **Penicillin
Congenital syphilis:
- Placenta: focal proliferative villitis with necrosis
- Most infants with congenital syphilis are asymptomatic at birth
- “Early” congenital syphilis: first 2 years
- “Late” congenital syphilis: near puberty
- Treatment: Penicillin
- Monitor: Serial VDRL
Clinical features of Congenital Syphilis
1. Skin
- Bullous rash over palm and sole, mucous membrane
- Reticuloendothelial system
- Hepatosplenomegaly + LN
- Hepatitis, Jaundice - Haematological
- Anaemia
- Thrombocytopenia
- WCC ↑↓ - Bone
- Metaphyseal and diaphyseal
- Osteochondritis
- Dactylitis - CNS
- Aseptic meningitis
- Chorioretinitis - Others
- Hydrops
- Rhinitis (purulent / haemorrhagic)
- Myocarditis
Toxoplasmosis
- Toxoplasma gondii (protozoa)
- Cats: complete hosts
- Infection through contaminated water / food
- Incidence varies 0-90%
Maternal infection:
- Asymptomatic / Mild symptoms
- Diagnosis: Serological: IgM, ↑ IgG
Fetal infection:
- More severe during first half of gestation
- Diagnosis: Cord blood for IgM
Management:
1. **Spiramycin “prophylaxis” once maternal infection documented
2. **Pyrimethamine + ***Sulfadiazine (for fetal infection) for 1 year
Congenital toxoplasmosis:
1. CNS
- Hydrocephalus
- Intracranial calcifications
- Others
- Eyes
- Chorioretinal scars
- Chorioretinitis
- Leucocoria
- Cataract
- Nystagmus
- Optic atrophy - Ears
- Deafness - Others
- Anaemia
- Cholestasis
- Hydrops
- Nephrotic syndrome
- Interstitial pneumonitis
Prognosis:
- Severe symptoms / Untreated —> Mental retardation / Blindness
- Treated —> Lesser degree of damage
Rubella infection
Maternal infection:
- Airborne + Direct contact
- Shedding of virus 1 week before rash appears
- 10% of child-bearing age women non-immune
- Time of maternal infection ↑ —> Chance of fetal infection ↑
Congenital infection:
1. Hearing
- ***Sensorineural deafness
- CNS
- ***Microcephaly
- Meningoencephalitis
- Mental retardation - CVS
- PDA
- Pulmonary stenosis - Eyes
- Cataracts
- Retinopathy
- Cloudy cornea
- Glaucoma
- Microphthalmia - Others
- IUGR
- DM
- Anaemia
- ***Hepatosplenomegaly
Prevention:
- Rubella vaccination
—> Theoretical risk of ***Teratogenicity of life-attenuated vaccine: CI during pregnancy
Hepatitis B
- 10% carrier rate in HK
- Late morbidity with cirrhosis, chronic hepatitis, HCC
Mode of transmission:
- **Perinatal
- **Blood / body fluid contact
Mother-to-infant transmission occurs during delivery in most cases through:
1. **Transplacental microhaemorrhages
2. **Ingestion of contaminated maternal secretions
- Chance of becoming carrier high
- Chance of ***“intrauterine” infection low (5%)
- Breast milk excretion: but not CI
Risk of transmission to neonate:
- Mother with HBeAg +ve: 80%
- Mother with HBeAg / Anti-HBe -ve: 30%
- Mother with Anti-HBe: 10%
Prevention:
Mother HBsAg negative:
1. HB vaccine at birth, 1 and 6 months old —> 95% seroconvert
Mother HBsAg positive:
1. HB vaccine + ***HBIG at birth
2. HB vaccine at 1 and 6 months old —> 95% protection
HSV infection
- HSV1, 2
- Primary infection
- Reactivation:
1. Gingivostomatitis
2. Pharyngitis
3. Genital tract infection
Perinatal HSV infection:
Transmission:
- Mostly acquire during passage through **infected birth canal
- Transplacental transmission **rare
Chance of Vertical transmission:
- Primary infection: 50%
- Reactivation: 5%
Clinical features:
- Mostly symptomatic within first week
—> **Vesicular skin and mucous membrane eruptions (first 10 days)
—> **Disseminated disease (9-11 days)
—> ***CNS: meningoencephalitis (15-17 days)
- Intrauterine infection rare
—> Microcephaly, Chorioretinitis, Microphthalmia
Diagnosis:
- Isolation of virus from vesicles / other body fluids
Treatment:
- ***Aciclovir
Prevention:
- ***C-section for women with S/S suggesting genital HSV infection at onset of labour
- Obtain viral cultures from newborn at 24-48 hours of life
CMV infection
- ~80-90% of women at child bearing age are ***seropositive
- Risk of susceptible women acquire primary CMV infection 1-2% during pregnancy
- Primary infection during pregnancy —> 40% fetal infection (Mild - Severe)
- Reactivation / Co-infection with exogenous strain during pregnancy —> Mild fetal infection
Maternal CMV infection:
- Mostly ***asymptomatic
- Diagnosis:
1. CMV-IgM (may persist in blood for up to 8 months)
2. ↑ IgG
3. PCR / CMV Ag
Congenital CMV infection:
- 0.4-1% of livebirths
- 10% **symptomatic at birth —> severe sequelae
- Diagnosis:
1. CMV isolated within first 2 weeks
- Treatment: **?Ganciclovir
Clinical features:
1. CNS
- **Microcephaly
- **Hypotonia
- Seizures
- Intracranial calcification
- Porencephalic cysts
- Eyes
- ***Chorioretinitis
- Optic atrophy - Hearing
- ***Sensorineural deafness - Reticuloendothelial systems
- ***Hepatosplenomegaly
- Cholestasis - Others
- ***Thrombocytopenia
Perinatal CMV infection:
- Benign
- Acquire CMV during / after delivery
HIV infection
Fetal transmission:
1. **In-utero
2. **Intrapartum (50%)
3. Postpartum: ***Breastfeeding (14%)
- 25% Fetal infection rate
Fetal and Neonatal infection:
- **Asymptomatic at birth
- Median age at presentation: **17 months
—> 25% develop AIDS by 1 yo
—> 50% by 4 yo
—> 33% AIDS free by 13 yo
Diagnosis:
- DNA-PCR
- Maternal transfer of IgG makes diagnosis difficult (median age of clearance 13 months)
Prevention of perinatal transmission (reduce chance by 50%):
1. Anti-retroviral agent (**Zidovudine)
- Start antenatally
- Intrapartum
- Postnatal for 6 weeks to newborn
2. **Avoid contamination during labour (prolonged labour, rupture of membrane, invasive monitoring, instrumental delivery)
3. **Septrin prophylaxis since 6 weeks until Dx excluded
4. Avoid **live vaccine / ***breastfeeding
Acute bacterial infection in Neonates
Route:
1. Ascending infection
- Colonised organism from maternal genital tract / urinary tract / GIT
2. Blood borne (via placenta) secondary to maternal sepsis
3. Postnatal infection
- Nosocomial infection
- Community acquired infection
Early Onset: Organisms from mother
Late onset:
1. Organisms from postnatal exposure (including breast milk)
2. Organisms (with long incubation period) from mother
- GBS, Listeria, Enterococcus etc.
Causative organisms:
1. Gram +ve
- GBS
- Other Streptococcus
- Enterococcus
- Staphylococcus
2. Gram -ve
- E. Coli
- Klebsiella
- Haemophilus influenzae
- Pseudomonas
3. Anaerobes
4. Fungus
- Candida
Risk factors:
1. Prolonged rupture of membrane (>18h)
2. Premature labour
3. Chorioamnionitis
4. Maternal fever >38oC
5. GBS colonisation
Clinical features:
Non-specific:
1. Temperature instability
2. Altered conscious state: Irritability / lethargy
3. Tachycardia / Bradycardia
4. Poor perfusion
5. Respiratory distress / Apnea
6. Abdominal distension
7. Hepatosplenomegaly
8. Feeding intolerance / Poor feeding
P/E:
1. Conscious state
2. Perfusion
3. Colour: Pallor / Cyanosis
4. Chest
- Tachypnea (RR ***>60/min)
- Crepitations
5. CVS
- Tachycardia / Bradycardia
6. Abdomen
- Distension (ileus)
- Hepatosplenomegaly
7. CNS
- Bulging anterior fontanelle
Investigations:
1. CBC
- **Hb (normal **14.5-24.5)
- **↑/↓ WBC (normal **5-30)
- Ratio of immature to total neutrophil (Band form: left shift of neutrophil lineage)
- **Thrombocytopenia (normal **>150)
2. CRP (2x negative rule out infection), ESR, IL6
3. Culture
- Blood
- Urine
- CSF
—> CSF / Blood glucose ratio (normal **>0.6)
—> Protein (normal **<0.5)
—> RBC (a few can be present due to traumatic tap)
- Gastric aspirate, Ear, Eyes etc.
4. X-ray
Treatment:
1. **Penicillin (or Ampicillin) for Gram +ve
2. **Aminoglycoside (or Cephalosporin) for Gram -ve
3. Combination for Empirical treatment
Group B Streptococcus (GBS)
Streptococcus agalactiae:
- Colonised in maternal genital tract 15-20%
- **Asymptomatic in mother
—> May cause **in-utero infection —> **Abortion / **IUD
—> **Premature labour
—> **Perinatal infection
- Colonisation difficult to eradicate
- Sensitive to ***Penicillin
Perinatal GBS infection:
- 1% of colonised pregnancy
- Vertical transmission 50-70%
- Neonatal colonisation rate 8-25%
- Early onset (usually **<=3 days) —> **Pneumonia, **Septicaemia
- Late onset (up to **90 days) —> ***Meningitis
Prevention of Perinatal GBS infection:
- Intrapartum maternal **Penicillin / **Ampicillin prophylaxis (to known carrier mothers) at onset of labour reduce maternal and neonatal GBS infection (50% ***early onset infection)
- Risk factor approach: treat whenever risk factors are present (no carrier detection)
Neonatal O2 saturation
- Normal: SpO2 >95% breathing in room air
Cyanosis:
- DeoxyHb >5g/dL
- Central cyanosis vs Peripheral cyanosis
Causes of Cyanosis:
1. Pulmonary
2. Cardiac
3. Persistent pulmonary hypertension
4. Others (e.g. Methaemoglobinaemia)
Lumbar puncture in neonates (Phoebe Lam)
Indication:
- When clinical suspicion is high (e.g. bulging fontanelle, seizure, s/s of meningitis)
Insert LP needle between vertebral bodies:
- L4-5 / L3-4 (not lower otherwise no fluid will come out)
- Spinal cord ends at L1
Possible complications:
1. Local trauma to spinal cord
2. Bleeding / Haematoma
- correct coagulopathy
- if DIC in sepsis, then do LP with FFP and platelet transfusion?
3. Introduce infection
4. Cardiopulmonary decompensation during positioning
- ∵ need to flex baby’s head and buttock to straighten spinal cord —> monitor for bradycardia / desaturation —> release / defer LP till baby more stable
5. Coning
- when there is ↑ ICP (unlikely in neonates because pressure can be released through open fontanelles (but may happen in obstructed hydrocephalus e.g. spinal cord pathologies like myelomeningocele, known brain malformation)
CSF interpretation:
1. CSF / Blood glucose ratio (normal **>0.6)
2. Protein (normal **<0.5)
3. RBC (a few can be present due to traumatic tap)
Normal CSF value (from HNNS09)
Protein: 0.15-0.45 g/L
Glucose: 2.8-3.9 mmol/L
Cell counts: 0-3 / mm^3
Organism: None
Appearance: Clear
