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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

5

congenital and perinatal viral infections

CMV, HSV, parvovirus, HIV

6

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

8

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

14

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?

18

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

19

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

22

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

30

Hep B

mother infectious if HepBsAg positive

transmission at time of birth

give HBIG and vaccine to newborn ASAP

Risk of transmission is 5-20% (w/out Rx)
Risk increases to 70-90% if mother HBeAg positive

asymptomatic baby doesn't mean anything

Hepatitis B acquired in childhood has higher chances of developing chronic hepatitis and ultimately Hepatocellular carcinoma and cirrhosis