Flashcards in Micro 2 Deck (33)
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1
TORCH
led to use of poor test... "TORCH titer"
2
serology IS the way to Dx:
syphilis, toxo
3
serology CANNOT Dx:
HSV, CMV
4
pyogenic bacterial infections
Group B strep, E. coli
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congenital and perinatal viral infections
CMV, HSV, parvovirus, HIV
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Frequency of congenital infections asymptomatic at birth
CMV >90%
Rubella 60-70%
Toxo 75%
syphilis 50% or more depending on definition
HIV >99% (may not manifest for 6mo-1yr b/c manifests as opportunistic infection)
HSV rarely asymptomatic!! <5%
7
Common findings in congenital non-pyogenic infections
hepatosplenomegaly
jaundice
anemia
pneumonia
adenopathy
petechiae
meningioencephalitis
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Distinctive features of congenital non-pyogenic infections:
intracranial calcifications
toxo, CMV
9
Distinctive features of congenital non-pyogenic infections:
cataracts
rubella, HSV
10
Distinctive features of congenital non-pyogenic infections:
chorioretinitis
toxo, CMV
11
Distinctive features of congenital non-pyogenic infections:
bone lesions
syphilis, rubella
12
Distinctive features of congenital non-pyogenic infections:
congenital heart dz
rubella
13
Distinctive features of congenital non-pyogenic infections:
microencephaly
CMV
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Distinctive features of congenital non-pyogenic infections:
hydrocephalus
toxo
15
Distinctive features of congenital non-pyogenic infections:
vesicles
HSV, VZV, syphilis
16
Syphilis
Treponema pallidum
difficult to culture... dark field microscopy!
Transmitted transplacentally: can be isolated (14 wks early in 74% women) from amniotic fluid; lack of pathological fetal changes before 5th month; hematogenous spread--> widespread problems in fetus
Risk to infant varies depending on mother's stage of untreated syphilis:
*primary and secondary: 50% stillbirth, 50% infected
*Latent: 20-60% normal
*Late: 70% normal
Placenta:
pale, thick, and larger than normal
Focal villositis with endovascular and perivascular proliferation (hypercellular)
Treponema may be identified by silver stain
17
Congenital syphilis presentation
asymptomatic usually at birth
w/in 2 yrs:
--multiorgan involvement
--non-immune hydrops
--hepatosplenomegaly
--bone involvement (periostitis)
--Cartilage involvement (snuffles)
--pneumonia
--derm changes (copper rash)
--desquamation? respiratory distress?
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Dx syphilis
Abs to cardiolipin (VDRL and RPR)
--can give false positives, so follow up w/...
detect Abs to T. pallidum
--i.e. MHA-TP microhemagglutination test
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Report of the Committee on Infectious Diseases (AAP) guidelines (for syphilis)
Mother’s serological status has to be determined prior to discharge
20
prenatal management for syphilis
RPR screening during pregnancy at least once
twice at least in high risk populations
21
prenatal Rx for syphilis
single dose of benzathine PCN
repeat wkly x2 for HIV concurrent
follow titers during pregnancy and document 4 fold drop in titers
re-treat any time 4-fold increase
Rx partner
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infant Rx for syphilis
procaine PCN
aqueous PCN
benzathine PCN IM if guaranteed F/U (inadequate CNS Rx w/ just one dose)
23
HIV
maternal screening is key! (congenital HIV is preventable)
Dx w/ culture and PCR;
If mother HIV+ and infant asymptomatic: Rx w/ AZT until PCR neg. two different times 6 wks apart
24
Rubella
Severe cases with mental retardation, microcephaly, cataracts, deafness, intradermal erythropoiesis (“blueberry muffin” appearance—not specific for rubella b/c can occur anytime anemia???)
stillbirth risk very high if first few wks of pregnancy
mother serology=key!
Dx viral culture and PCR
25
Congenital toxo
more commonly transmitted later in pregnancy, but more of a problem if transmitted early
Severe cases often with hydrocephalus, chorioretinitis, jaundice, splenomegaly, intracranial calcifications (diffuse)
calcifications on CT are diffuse (b/c comes from blood stream?)
Early Dx is essential for Rx
80-90% develop neuro sequelae, esp. eyes
Dx w/ serology! (very sensitive, postitive titers require confirmation)
Rx long and complicated (pyrimethamine and sulfadiazine)
26
CMV
probably most common perinatal infection
in utero, natally, or post-natally aquired
congenital: smallest percentage of births, but bad and long term sequelae
natal: 2-6%
post-natal: 14-21%... natal and postnatal usually not severe (URI) unless immunosuppressed
27
congenital CMV invections
most >90% asymptomatic
primary maternal infection (gets CMV for first time while pregnant) causes more of the problems, but secondary can cause some!
MC symptoms when symptomatic:
jaundice, petechiae, hepatosplenomegaly, IUGR, preterm, microcephaly, etc.
dilated ventricles, periventricular calcifications, w/ small head on CT
Dx: Isolation of CMV from urine or other body fluid (CSF, blood, saliva) in the first 21 days of life is considered proof of congenital infection
serology bad, PCR good
28
Sequelae of congenital CMV
neuro=most common and most severe
>90% of symptomatic have visual, audiologic, etc.
5-17% of ASYMPTOMATIC congenital CMV still develop neuro sequelae!!! i.e. hearing loss
cranial CT is good predictor of sequelae
29
HSV
primary infection>>>recurrent infection
Skin-mouth-eye (SEM) dz 6-10 days old
disseminated dz w/ or w/out CNS 5-7 days
encephalitis alone presents days later
25% long-term CNS sequelae
Dx: DFA testing of specimen from skin; culture=gold standard, but unhelpful for CNS involvement; PCR
Rx: 14 days if SEM, 21 days if CNS
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