Medical Laboratory Science Exam questions and answers fully solved
serum antibody response usually characterizes the primary (early) stage of syphilis?
A. Antibodies against syphilis are undetectable
B. Detected 1-3 weeks after appearance of the primary chancre
C. Detected in 50% of cases before the primary chancre disappears
D. Detected within 2 weeks after infection - AnswersB During the primary stage of syphilis,
about 90% of patients develop antibodies between 1 and 3 weeks after the appearance of the
primary chancre.
What substance is detected by the rapid plasma reagin (RPR) and Venereal Disease Research
Laboratory (VDRL) tests for syphilis?
A. Cardiolipin
B. Anticardiolipin antibody
C. Anti-T. pallidum antibody
D. Treponema pallidum - AnswersB. Anticardiolipin antibody
B Reagin is the name for a nontreponemal antibody that appears in the serum of syphilis-
infected persons and is detected by the RPR and VDRL assays. Reagin reacts with cardiolipin, a
lipid-rich extract of beef heart and other animal tissues.
What type of antigen is used in the RPR card test?
A. Live treponemal organisms
B. Killed suspension of treponemal organisms
C. Cardiolipin
D. Tanned sheep cells - AnswersC Cardiolipin is extracted from animal tissues, such as beef
hearts, and attached to carbon particles. In the presence of reagin, the particles will agglutinate.
Which of the following is the most sensitive test to detect congenital syphilis?
,A. VDRL
B. RPR
C. Microhemagglutinin test for T. pallidum (MHA-TP)
D. Polymerase chain reaction (PCR) - AnswersD The PCR will amplify a very small amount of DNA
from T. pallidum and allow for detection of the organism in the infant. Antibody tests such as
VDRL and RPR may detect maternal antibody only, not indicating if the infant has been infected.
A biological false-positive reaction is least likely
with which test for syphilis?
A. VDRL
B. Fluorescent T. pallidum antibody absorption test (FTA-ABS)
C. RPR
D. All are equally likely to detect a false-positive result - Answers. B The FTA-ABS test is more
specific for T. pallidum than nontreponemal tests such as the VDRL and RPR and would be least
likely to detect a biological false-positive result. The FTA-ABS test uses heat-inactivated serum
that has been absorbed with the Reiter strain of T. pallidum to remove nonspecific antibodies.
Nontreponemal tests have a biological false-positive rate of 1%-10%, depending upon the
patient population tested. False-positive findings are caused commonly by infectious
mononucleosis (IM), SLE, viral hepatitis, and human immunodeficiency virus (HIV) infection.
A 12-year old girl has symptoms of fatigue and a localized lymphadenopathy. Laboratory tests
reveal a peripheral blood lymphocytosis, a positive RPR, and a positive spot test for IM. What
test should be performed next?
A. HIV test by ELISA
B. VDRL
C. Epstein-Barr virus (EBV) specific antigen test
D. Treponema pallidum particle agglutination (TP-PA) test - AnswersD The patient's symptoms
are nonspecific and could be attributed to many potential causes. However, the patient's age,
lymphocytosis, and serological results point to infectious mononucleosis (IM). The rapid spot
test for antibodies seen in IM is highly specific. The EBV-specific antigen test is more sensitive
but is unnecessary when the spot test is positive. HIV infection is uncommon at this age and is
often associated with generalized lymphadenopathy and a normal or reduced total lymphocyte
count. IM antibodies are commonly implicated as a cause of biological false-positive
, nontreponemal tests for syphilis. Therefore, a treponemal test for syphilis should be performed
to document this phenomenon in this case
Which test is most likely to be positive in the tertiary stage of syphilis?
A. FTA-ABS
B. RPR
C. VDRL
D. Reagin screen test (RST) - AnswersA The FTA-ABS or one of the treponemal tests is more likely
to be positive than a nontreponemal test in the tertiary stage of syphilis. In some cases,
systemic lesions have subsided by the tertiary stage and the nontreponemal tests become
seronegative. Although the FTA-ABS is the most sensitive test for tertiary syphilis, it will be
positive in both treated and untreated cases
What is the most likely interpretation of the following syphilis serological results?
RPR: reactive; VDRL: reactive; MHA-TP: nonreactive
A. Neurosyphilis
B. Secondary syphilis
C. Syphilis that has been successfully treated
D. Biological false positive - Answers. D A positive reaction with nontreponemal antigen and a
negative reaction with a treponemal antigen is most likely caused by a biological false-positive
nontreponemal test.
Which specimen is the sample of choice to evaluate latent or tertiary syphilis?
A. Serum sample
B. Chancre fluid
C. CSF
D. Joint fluid - AnswersC Latent syphilis usually begins after the second year of untreated
infection. In some cases, the serological tests become negative. However, if neurosyphilis is
present, cerebrospinal fluid serology will be positive and the CSF will display increased protein
and pleocytosis characteristic of central nervous system infection.
Interpret the following quantitative RPR test
results.
serum antibody response usually characterizes the primary (early) stage of syphilis?
A. Antibodies against syphilis are undetectable
B. Detected 1-3 weeks after appearance of the primary chancre
C. Detected in 50% of cases before the primary chancre disappears
D. Detected within 2 weeks after infection - AnswersB During the primary stage of syphilis,
about 90% of patients develop antibodies between 1 and 3 weeks after the appearance of the
primary chancre.
What substance is detected by the rapid plasma reagin (RPR) and Venereal Disease Research
Laboratory (VDRL) tests for syphilis?
A. Cardiolipin
B. Anticardiolipin antibody
C. Anti-T. pallidum antibody
D. Treponema pallidum - AnswersB. Anticardiolipin antibody
B Reagin is the name for a nontreponemal antibody that appears in the serum of syphilis-
infected persons and is detected by the RPR and VDRL assays. Reagin reacts with cardiolipin, a
lipid-rich extract of beef heart and other animal tissues.
What type of antigen is used in the RPR card test?
A. Live treponemal organisms
B. Killed suspension of treponemal organisms
C. Cardiolipin
D. Tanned sheep cells - AnswersC Cardiolipin is extracted from animal tissues, such as beef
hearts, and attached to carbon particles. In the presence of reagin, the particles will agglutinate.
Which of the following is the most sensitive test to detect congenital syphilis?
,A. VDRL
B. RPR
C. Microhemagglutinin test for T. pallidum (MHA-TP)
D. Polymerase chain reaction (PCR) - AnswersD The PCR will amplify a very small amount of DNA
from T. pallidum and allow for detection of the organism in the infant. Antibody tests such as
VDRL and RPR may detect maternal antibody only, not indicating if the infant has been infected.
A biological false-positive reaction is least likely
with which test for syphilis?
A. VDRL
B. Fluorescent T. pallidum antibody absorption test (FTA-ABS)
C. RPR
D. All are equally likely to detect a false-positive result - Answers. B The FTA-ABS test is more
specific for T. pallidum than nontreponemal tests such as the VDRL and RPR and would be least
likely to detect a biological false-positive result. The FTA-ABS test uses heat-inactivated serum
that has been absorbed with the Reiter strain of T. pallidum to remove nonspecific antibodies.
Nontreponemal tests have a biological false-positive rate of 1%-10%, depending upon the
patient population tested. False-positive findings are caused commonly by infectious
mononucleosis (IM), SLE, viral hepatitis, and human immunodeficiency virus (HIV) infection.
A 12-year old girl has symptoms of fatigue and a localized lymphadenopathy. Laboratory tests
reveal a peripheral blood lymphocytosis, a positive RPR, and a positive spot test for IM. What
test should be performed next?
A. HIV test by ELISA
B. VDRL
C. Epstein-Barr virus (EBV) specific antigen test
D. Treponema pallidum particle agglutination (TP-PA) test - AnswersD The patient's symptoms
are nonspecific and could be attributed to many potential causes. However, the patient's age,
lymphocytosis, and serological results point to infectious mononucleosis (IM). The rapid spot
test for antibodies seen in IM is highly specific. The EBV-specific antigen test is more sensitive
but is unnecessary when the spot test is positive. HIV infection is uncommon at this age and is
often associated with generalized lymphadenopathy and a normal or reduced total lymphocyte
count. IM antibodies are commonly implicated as a cause of biological false-positive
, nontreponemal tests for syphilis. Therefore, a treponemal test for syphilis should be performed
to document this phenomenon in this case
Which test is most likely to be positive in the tertiary stage of syphilis?
A. FTA-ABS
B. RPR
C. VDRL
D. Reagin screen test (RST) - AnswersA The FTA-ABS or one of the treponemal tests is more likely
to be positive than a nontreponemal test in the tertiary stage of syphilis. In some cases,
systemic lesions have subsided by the tertiary stage and the nontreponemal tests become
seronegative. Although the FTA-ABS is the most sensitive test for tertiary syphilis, it will be
positive in both treated and untreated cases
What is the most likely interpretation of the following syphilis serological results?
RPR: reactive; VDRL: reactive; MHA-TP: nonreactive
A. Neurosyphilis
B. Secondary syphilis
C. Syphilis that has been successfully treated
D. Biological false positive - Answers. D A positive reaction with nontreponemal antigen and a
negative reaction with a treponemal antigen is most likely caused by a biological false-positive
nontreponemal test.
Which specimen is the sample of choice to evaluate latent or tertiary syphilis?
A. Serum sample
B. Chancre fluid
C. CSF
D. Joint fluid - AnswersC Latent syphilis usually begins after the second year of untreated
infection. In some cases, the serological tests become negative. However, if neurosyphilis is
present, cerebrospinal fluid serology will be positive and the CSF will display increased protein
and pleocytosis characteristic of central nervous system infection.
Interpret the following quantitative RPR test
results.
