TORCH, Spirochetes, Mono Flashcards
What does TORCH stand for?
T = toxoplasmosis
O = others perinatal infections (gonorrhea, syphilis, HIV)
R = Rubella
C = CMV
H = Herpes
What is TORCH used for?
Prenatal screening test
Toxoplasmosis - infectious agent. Modes of transmission
Toxoplasma gondii
-cannot be cultured
From cats or uncooked meats
Toxoplasmosis gold standard. Another test includes…
Sabin-Feldman Dye test
EIA
Toxoplasmosis - clinical findings
Mono-like symptoms
Hydrocephalus birth defects
Difference between EBV and CMV
EBV produces heterophile antibodies
CMV does not
CMV is a member of…
Herpes virus
-almost everyone has it
CMV - clinical findings
Neurological symptoms = mental-retardation, stillbirth
Mono-like symptoms
Cold sores, blisters
-mostly asymptomatic
Rubella - at what titer is a person considered immune? A recent infection has these findings…
1:8
4 fold increase in titer with symptoms
Rubella - clinical findings
Defects - CHF
Hepatitis
Diabetes
Rubella tests
EIA
Latex agglutination
Hemagglutination inhibition (HAI) - rubella can agglutinate chick RBCs. Mix patient serum with RBCs. Antibodies present = no agglutination
Passive hemagglutination (PHA) - human RBCs coated with Rubella antigen and serum diluted. Positive result is RBC agglutination (antigen-antibody complex)
What type of virus is the herpes virus? Which herpes virus is genital herpes?
DNA virus
HSV-II
Herpes tests
EIA
Viral culture - reference lab
Herpes - clinical findings
Fatal to infant if transmitted
Can spirochetes be gram-stained?
No
Syphilis bacterium
Treponema pallidum
- fragile, need open lesion to pass
- mother can transmit to newborn
- quickly disseminate throughout body in 30 mins
Syphilis - clinical findings
Primary (chancre)
Secondary (lymphadenopathy, skin rash, sore throat)
Latent (asymptomatic)
Tertiary (granulomatous inflammation, cardiovascular disease, neurosyphilis)
Congenital syphilis - clinical findings
Generalized lymphadenopathy, hepatosplenomegaly, jaundice, anemia, bone abnormalities, neurosyphilis
Facial deformity: Hutchinson’s teeth
Suspected Treponema infection should be screened for… Confirm with…
Non-treponemal antibodies first
- MUST be confirmed
- test is non-specific to treponema
Confirm with treponemal antibodies assay - cumbersome, expensive, lengthy
What are Reagin antibodies? What do Reagin antibodies target?
Antibodies that develop targeting cholesterol-containing compounds in the cell membrane when they rupture from a syphilis infection
- seen as “foreign”
- Reagin is non-specific, seen in old people, autoimmune, cancer, TB, chickenpox, hepatitis
- diminish over time
Cardiolipin
Direct lab diagnosis of syphilis (2)
Fluorescent microscopy
Darkfield microscopy - corkscrew morphology, flexing mobility
-cannot be gram-stained
Serological tests for syphilis are divided into two categories. Which is screening and which is confirmatory?
Non-treponemal = screening
Treponemal = confirmatory
What are the 2 non-treponemal tests? Are they sensitive or specific for treponema?
VDRL and RPR
-look for flocculations = cardiolipin clumping
Both sensitive but not specific for treponema
VDRL vs RPR - which one is easier to do? Benefit of VDRL?
RPR - sensitive, faster, no microscope needed
Can be used on CSF samples
VDRL - weakness. What are the results?
Temperature sensitive - antigen MUST be prepared between 23-29C
Reactive - medium/large clumps
Weakly reactive - small clumps
Nonreactive - no clumps
-uses microscope for observation
RPR - cardiolipin antigen is attached to… What are the results?
Charcoal
Reactive - medium/large clumps
Weakly reactive - small clumps
Nonreactive - no clumps. A “tail” is seen when swirled
-can be observed by eye
Treponema confirmatory tests (4)
Fluorescent treponemal absorption (FTA-ABS) - antibodies to treponema. Remove cross-reacting antibodies in serum with sorbent first. Fix treponema to slide, add serum and conjugate Ig, observe fluorescence
-gold standard
T. pallidum passive/particle agglutination (TP-PA) - agglutination on plate
Microhemagglutination assay (MHA-TP) - discontinued
Immunoassays/ELISA - by request
Treponemal vs non-treponemal - how do test results look over time
Treponemal titers appear during primary syphilis and remain elevated for life
Non-treponemal titers decline over time - peak at secondary-early latent stages
Why do non-treponemal (RPR and VDRL) tests decline over time?
Patient recovers after treatment, antibodies decline in later stages of syphilis
-elevated for first 6 months of infection
When testing fetuses for congenital syphilis, why should we look for IgM instead of IgG?
IgG comes from mother through placenta, false positive
-syphilis can cross placenta as well
Neurosyphilis patients should be tested using these tests (2)
ELISA
VDRL using CSF
3 types of diseases caused by spirochetes
Syphilis
Lyme disease
Relapsing fever
Lyme disease - caused by…
Borrelia burgdorferi
Lyme disease - clinical manifestations
Stage 1 Localized rash Stage 2 Early dissemination Stage 3 Late dissemination with arthritis
Lyme disease diagnosis
ELISA
Western blot - ELISA followup
IgM and IgG antibody levels
- IgM = recent
- IgG = awhile ago
Lyme disease - western blot MUST show this band… It must also be positive for…
41 kDa + 2 other bands specific for spirochete
This disease mimics Lyme disease… caused by…
Relapsing fever
Borrelia miyamotoi
Mono - caused by this virus… Virus is part of this family…
EBV = oncogenic
Herpes
How is mono detected?
ELISA
Heterophile antibody
Mono causes a rise in…
Lymphocytes - 50% lymphocytosis = more Igs
Spike in gammaglobulins
Mono produces heterophile antibodies that are this Ig class…
IgM
How are heterophile antibodies tested for (2)
Paul Burnell heterophile antibody test
Davidsohn differential test
Mono test result for differential test
Negative - bovine RBC + sheep RBC + serum = no agglutination
Positive - guinea pig kidney + sheep RBC + serum = agglutination
First EBV antibody to appear during an infection
Anti-VCA (IgM)
-virus capsid antigen
