27-28th Page Flashcards
What do treponemal tests detect?
Detect antibodies directed against the T. pallidum organism or against specific treponemal antigens.
Are treponemal tests easy to perform?
No, treponemal tests are more difficult to perform and time-consuming.
What type of antibodies are predominantly found in early or untreated early latent syphilis?
predominantly IgM antibodies.
What follows the early immune response to T. pallidum infection?
ppearance of IgG antibodies, which soon become predominant.
When is the greatest elevation in IgG concentration seen?
in secondary syphilis.
What is the Treponema Pallidum Immobilization Test (TPI)?
The TPI uses patient serum with live, actively motile T. pallidum extracted from testicular chancre of rabbit and complement.
positive TPI
Positive: >50% of treponemes are immobilized.
negative TPI
Negative: If fewer than 20% are immobilized.
doubtful TPI
Doubtful: Ranges 20 - 50% are immobilized.
What is the principle of the Fluorescent Treponemal Antibody Absorption Test (FTA-ABS)?
FId
indirect immunofluorescence
What is nonpathogenic treponemes in FTA-ABS
Reiter
What happens to the patient serum in the FTA-ABS test?
The patient serum is heat-inactivated and treated with a sorbent to remove cross-reactivity with treponemes other than T. pallidum.
How is the intensity of fluorescence reported in the FTA-ABS test?
green color is reported on a scale of 0 to 4.
reactive FTA-ABS
Reactive: 2+ to 4+.
negative FTA-ABS
Negative: No fluorescence.
FTA-ABS test is minimally reactive
If minimally reactive (1+), the test must be repeated with a second specimen drawn in 1 to 2 weeks.
what strain of T.pallidum is fixed to slides that is used for the test?
Nichol
TPHA test (TPHA (T. pallidum hemagglutination assay)
uses tanned sheep RBCs coated with antigen from the Nichols strain.
TAPA test? TAPA (T. pallidum particle agglutination assay)
uses gel particles sensitized with T. pallidum sonicate.
MHA-TP (micro hemagglutination assay for T. pallidum)
using formalinized, tanned sheep RBCs sensitized with antigen from the Nichols strain.
performed using microtiter plates
HATTS (Hemagglutination Treponemal test for Syphilis)
using glutaraldehyde stabilized turkey RBC.
What is the MONOSPOT TEST?
A rapid differential slide test that uses horse RBCs as an indicator.
More sensitive compared to the Davidson differential test.
positive result in the MONOSPOT TEST?
Dark clumps against a blue-green background, distributed uniformly throughout the test circle.
negative result in the MONOSPOT TEST?
No agglutination but may have fine granularity against a brown-tan background.
What is MONOTEST?
A test using ox hemolysin with ox RBCs and classical methods like 2% sheep RBCs.
What is the role of papain in the MONOTEST?
Papain destroys IM receptors and treated Sheep RBCs
Anti-VCA?
Produced by infected B cells and found in the cytoplasm,
Can persist for life.
detectable early in infection, but low conc. and disappears within 2 to 4 months.
Anti-VCA IgM
Where is Anti-EA found?
In the nucleus and cytoplasm of B cells, strongly indicating active infection.
What is Anti-EBNA?
Found in the nucleus of all EBV-infected cells
absent or barely detectable during acute IM.
Anti-EBNA IgG appears during the convalescent period.
EBV-Associated IM in the acute phase (0-3 months)?
Specific:
VCA IgM: Pos,
VCA IgG: Po
EA (D or R): Pos/Neg
EBNA: Neg.
Non-specific:
Heterophile IgM: Pos
EBV-Associated IM in the recent phase (3-12 months)?
Specific:
VCA IgM: Pos
VCA IgG: Pos
EA (D or R): Pos/Neg
EBNA: Pos.
Non-specific:
Heterophile IgM: Neg
EBV-Associated IM in the past phase (>12 months)?
Specific:
VCA IgM: Neg
VCA IgG: Pos
EA (D or R): Neg
EBNA: Pos.
Non-specific:
Heterophile IgM: Neg
What is infectious mononucleosis?
An acute infectious disease of the Reticuloendothelial system caused by EBV.
What are the target cells for infectious mononucleosis?
C3d receptor (CD21).
Kissing dse or Glandular fever
Infectious Mononucleosis
What is the mode of transmission for infectious mononucleosis?
Intimate contact with salivary secretion from an infected individual.
What are the manifestations of infectious mononucleosis?
High WBC count (leukocytosis);
Differential count (>50% lymphocytes);
Increased WBC with >10% atypical lymphocytes (Downey cells);
Presence of heterophile antibodies.
What is significant about heterophile antibodies in serologic tests of IM?
A titer of 1:56 or greater is clinically significant in patients with suspected infectious mononucleosis.
What is a titer?
The highest dilution of serum that still shows a positive result.
What is the Paul-Bunnel test?
A screening test/ presumptive hemagglutination test that measures total heterophile antibodies using sheep RBCs.
What does the presence of agglutination in the Paul-Bunnel test indicate?
A positive reaction of heterophile antibodies.
What types of heterophile antibodies can be detected if there is agglutination?
- Antibodies to Forsmann antigen
- Antibodies in serum sickness
- Antibodies in infectious mononucleosis.
What is the Davidsohn differential test?
A test that involves adsorption with guinea pig cells, beef and Ox RBCs to differentiate types of heterophile antibodies.
What are the steps in the Davidsohn differential test?
- Adsorption
- Addition of indicator cells (Sheep RBCs)
- Interpretation for agglutination with sheep RBC
What is Hepatitis?
Inflammation of the liver.
What is Falminant Hepatitis?
Term applied when the number of hepatocytes destroyed is so few that they cannot maintain basic liver function.
What is Hepatitis A (HAV)?
Non-enveloped, icosahedral, ssRNA virus from the family PicoRNAviridae.
What is the mode of transmission (MOT) for Hepatitis A?
Fecal-oral.
What are the diagnostic markers for Hepatitis A?
HAV Ag and Anti-HAV antibodies.
What specimen is used to detect HAV Ag?
Stool.
What specimen is used to detect Anti-HAV?
Serum.
What is Hepatitis B (HBV)?
A virus from the family Hepadnaviridae (dsDNA) that exists in three forms: spherical particle, filamentous form, and Dane particle.
What is the mode of transmission (MOT) for Hepatitis B?
Parenteral, sexual, perinatal.
What are the HBV markers?
HBSAg
HBeAg
HBcAg
What is the earliest detectable HBV marker?
HBsAg.
What is the lifelong marker antibodies for HBV?
Anti-HBc.
What does the presence of Anti-HBc IgM indicate?
Acute phase marker.
What does the presence of Anti-HBc IgG indicate?
Chronic phase marker
Dane particle?
It represents the virion and is seen in blood, semen, urine, colostrum, and other body fluids.
What is the mortality rate associated with chronic Hepatitis B?
Less than 1.2%.
How many % in chronic hepatitis (HBV)
5-1%
Anti-EA found in nucleus and cytoplasm of B cells
EA-D
Found as a mass only in cytoplasm
EA-R
Does not appear until a px has entered the convalescent period
Anti-EBNA IgG
What RBC is used in Paul-Bunnel Test
Sheep RBC
Ab produced by one species and can infect other species
Heterophile Ab
In Paul-Bunnel Test, serum is serially diluted
TRUE
Endpoint titer in Paul-Bunnel
1:56
IM, Serum sickness, Forssman-induced
Sheep
Horse
Are all +
The only source of Ab with negative Beef RBC
Forssman-induced
The only source of Ab with negative guinea pig kidney
IM
Where are HAV located
primarily in cytoplasm of liver where it multiplies easily
Infectious Hepatitis/ Short Incubation hepatitis
HAV
More common in countries with low standard’s of living
Poorman’s hepatitis
Marker of Acute Hepatitis A
IgM anti-HAV
peaks during 1st month of illness
produced as a result of natural infection or immunization
IgG anti-HAV
predominant form seen in blood in dsDNA (HBV)
Spherical
Slightly less common in dsDNA (HBV)
Filamentous
represents the virion (least common)
Dane particle
Serum hepatitis/ Long-incubation hepatitis
HBV
Antigens of high infectivity, high vertical transmission
HBeAg
Antigens not found in blood (only infected hepatocytes)
HBcAg
Liver FNAB
HBcAg
The only antibody detected in window phase
Anti-HBc
Low infectivity marker (Low MOT)
Convalescence
Anti-HBe
Ab last to appear
Anti-HBS
Immune state marker
Anti-HBS
