Infectious Disease Flashcards
The classic triad of congenital HSV
- cutaneous
- skin vesicles or scarring (hypopigmented) present at birth
- neurologic
- microcephaly
- abnormal brain computed tomography findings identified within the first week after birth
- ophthalmologic
- chorioretinitis identified within the first week after birth
- microphthalmia
HSV is a double stranded DNA virus just like CMV, EBV, varicella, HHV6
What is most common intrauterine infection
CMV
- Most asymptomatic
- Symptoms 10%
- Jaundice, petechiae, hepatosplenomegaly
- microcephaly
- sensorineural hearing loss (progressive if not treated)
- Chorioretinitis
- Gold standard dx: Urine CMV culture
- Treat if symptomatic with ganciclovir x 6 wks or valacyclovir x 6 mos
- SE: neutropenia
What are the most common congenital infections
What is the source of infection of rubella
Humans
- Transmission: direct or droplet contact from nasopharyngeal secretions.
- Replicates in the respiratory mucosa and cervical lymph nodes before reaching the target organs via systemic circulation.
- Infectious period: 8 days before to 8 days after the rash onset.
How can a baby with congenital rubella spread the virus
- continue to spread the virus in nasopharyngeal secretions and urine for a year or more.
- recovered from lens aspirates in children with congenital cataracts for several years.
Incidence of fetus acquiring congenital rubella based on gestational age
85%: during the first 12 weeks of gestation,
50%: during the first 13 to 16 weeks of gestation
25%: latter half of the second trimester
- has a U-shape distribution
Findings of congenital rubella
- Congenital heart defects: PDA, PPAS, VSD, ASD
- Auditory: sensorineural hearing impairment (most common)
- Ophthalmologic: cataracts, pigmentary retinopathy, microphthalmos, chorioretinitis
- Neurologic: microcephaly, cerebral calcifications, meningoencephalitis, behavioral disorders, mental retardation
- Hematologic: thrombocytopenia, hemolytic anemia, petechiae/purpura, dermal erythropoiesis causing “blueberry muffin” rash
- Neonatal manifestation: low birth weight, interstitial pneumonitis, radiolucent bone disease leading to “celery stalking” of long bone metaphyses, hepatosplenomegaly)
- Delayed onset of insulin-dependent diabetes and thyroid disease.
Fetal Diagnosis of rubella
Detection of viral genome in amniotic fluid, fetal blood or chorionic villus biopsies (PCR).
Postnatal diagnosis of congenital rubella syndrome
- RV-IgG antibodies in neonatal serum using ELISA.
- sensitivity and specificity of nearly 100% in infants less than three months of age.
- Confirmation: detection of rubella virus in nasopharyngeal swabs, urine and oral fluid using PCR
Strongest predictors of EOS with greatest clinical utility
- gestational age
- Intraamniotic infection (Maternal temp 102.2F, or 100.4-102 with additional clinical factor)
- Neonatal clinical illness
Most common pathogenesis of EOS
ascending colonization of the uterine compartment with maternal GI/GU organism (ie ureplasma)
Predominant pathogen for EOS in (1) term, (2) preterm
(1) GBS
(2) E coli
Factors associated with near zero-risk EOS
Elective CS not in labor (no attempts in induction)
ROM at delivery
No signs of fetal distress
True or False- Maternal IAP exposure affects on reliability of blood CS or time to positivity
False
True or false- Ampicillin and gentamicin is not enough coverage for EOS
False
- Despite increasing resistance, Amp and gent provide optimal coverage for >90% of EOS
- Broad spectrum antibx later inc risk for NEC, fungal infxn, dysbiosis
It is sepsis accompanied by low BP
Septic shock
Major risk factor for LOS (late onset sepsis)
Preterm birth
Critical Illness
- central cath
- mech vent
- prolong TPN
- surgical intervention
Pathogen of LOS
- High income countries: Gm Pos
- 50% CoNS
- Mid-low income: Gm neg
- 3-10% Fungal (candida)
LOS pathogen associated with higher illness severity, higher mortality, short and long term morbidities
Gm Neg
- E coli
- Klebsiella
- Pseudomonas
- Enterobacter
Role of CRP or procalcitonin in sepsis management
- serial measurements result in a higher sensitivity and negative predictive value
- assist in discontinue antibiotics
Best practice for blood culture collection and volume requirement
- Disinfect with chlorhexidine (the longer- >30sec and allow to dry)
- Culture from peripheral site
- Blood volume: at least 1 ml (63% detection)
- 0.5 ml 39%
- 3 ml 95%
only 9% Bld Cs would be positive
betadine can be systemically absorbed- hypothyroidism
Preventive measures for LOS
- hand hygiene
- aseptic protocol
- antimicrobial stewardship
- care protocol: enteral feeds, breastmilk
Sepsis attributable mortality risk based on pathogen
higher mortality: fungal and Gm neg
31% fungal
20% Gm Neg: Pseudomonas
15% Gm Pos
Major sequela of LOS
Neurodevelopmental impairment
- from direct bacterial cytotoxicity, adverse systemic inflammation, altered brain perfusion
- White matter injury (oligodendrocyte injury)
- Noted as intellectual impairment on culture pos LOS
Postnatal growth failure- persists until NICU d/c
True or false prolonged empiric antibiotics is associated with LOS
True
empiric antibiotics >4 days at birth associated with 1.25-2.5 fold higher odd for LOS and mortality
Most common causative org of UTI
E coli (80%)
-Klebsiella and enterobacter
Condition associated with E coli sepsis
Galactosemia
Predisposing Factors for UTI in infants
Neonatal:
- Male (<3 months)
- Uncircumcised
- Prematurity
- Renal and urinary tract malformation
- high temperature (>102.2F)
Maternal characteristics
- History of UTI
- PROM
- Exposure to antibiotics
Etiology of UTI associated with VUR
Klebsiella
Hyperbilirubinemia and UTI
Elevated direct bilirubin- screen for UTI