Deck 21: Serologic and Molecular Detection of Bacterial Infections

Question 1

Which of the following is a cause of a biological false-negative in the screening tests for syphilis?

A) rotated too long
B) rheumatoid arthritis
C) latent syphilis
D) slow rotator speed

Answer 1

latent syphilis

Question 2

A patient presents with a painless genital ulcer.The patient is then diagnosed as having syphilis.In what stage of syphilis is the patient?

A) primary
B) secondary
C) latent
D) tertiary

Answer 2

primary

Question 3

A new technologist is busy one night and has to perform an RPR on a serum sample.He does not calibrate the needle delivering the antigen and the needle is delivering a larger volume of antigen than it is supposed to.What kind of error can this cause on the test result?

A) laboratory-induced false-negative due to postzone
B) laboratory-induced false-positive due to prozone
C) biological false-positive
D) biological false-negative

Answer 3

laboratory-induced false-negative due to postzone

Question 4

RPR stands for

A) reagin plasma reactive
B) reactive phosphate reagent
C) rapid plasma reagin
D) random positive reagin

Question 5

Lyme disease is caused by:

A) Treponema pallidum
B) Borrelia recurrentis
C) Leptospira autumnalis
D) Borrelia burgdorferi

Question 6

A patient is suspected of having latent syphilis.Which set of test results for RPR,MHA-TP,and CSF-VDRL best confirms this diagnosis?

A) RPR = R-8 dils; MHA-TP = reactive; VDRL = R-4 dils
B) RPR = nonreactive; MHA-TP = reactive; VDRL = nonreactive
C) RPR = nonreactive; MHA-TP = nonreactive; VDRL = nonreactive
D) RPR = R-2 dils; MHA-TP = nonreactive; VDRL = nonreactive

Question 7

A 30-year-old man presents to the physician with a painless ulcer on his penis.An RPR performed on the man is reactive 1:128,and the MHA-TP test is positive.This man has:

A) Neisseria gonorrhoeae
B) Chlamydia trachomatis
C) Treponema pallidum
D) Mycoplasma hominis

Question 8

The RPR and VDRL are similar in which of the following ways? RPR and VDRL are both:

A) read macroscopically
B) flocculation reactions
C) specific assays for syphilis
D) antigen detection assays

Question 9

Which of the following is a cause of a laboratory-induced false-negative in the screening tests for syphilis?

A) alcohol ingestion prior to blood draw
B) systemic lupus erythematosus
C) excess serum
D) hot laboratory

Question 10

At which stage of syphilis is the RPR the most sensitive?

A) primary
B) secondary
C) tertiary
D) latent

Question 11

Which of the following is a cause of a biological false-positive in the screening assays for syphilis?

A) prozone
B) reagents too cold
C) sera dried on card
D) autoimmune disease

Question 12

A patient presents with personality changes,altered mental state,and delusions of grandeur.The patient is then diagnosed as having syphilis.In what stage of syphilis is the patient?

A) primary
B) secondary
C) latent
D) tertiary

Question 13

Patient serum is mixed with sheep red blood cells that have been sensitized with Treponema pallidum antigens as well as with unsensitized red blood cells in a separate well.Agglutination was observed in the well with sensitized red blood cells and not in the well with unsensitized red blood cells.What is the interpretation of these results?

A) positive for anti-Treponema pallidum antibodies
B) positive for heterophile antibodies
C) negative for anti-Treponema pallidum antibodies
D) negative for anticardiolipin antibodies

Question 14

A 32-year-old heterosexual male presents to the physician with a 3-day history of multiple skin lesions located all over his body and on his mucous membranes.He hasn't felt well and has a low-grade fever.The patient cuts down trees in Massachusetts for a living.He is single,has had multiple sex partners,and does not use condoms.Here are the results of his laboratory tests: rapid plasma reagin = reactive 1:128; Treponema pallidum-particle agglutination assay = reactive; Borrelia burgdorferi IgM = < 1:8; Rickettsia rickettsii IgM < 1:8.This patient has:

A) primary syphilis
B) secondary syphilis
C) lyme disease
D) Rocky Mountain spotted fever

Question 15

The RPR and VDRL tests differ from each other in which of the following ways?

A) method for reading or visualizing the reaction
B) specificity of antibody detected
C) specificity of antigen detected
D) principle for detecting antigen-antibody complexes

Question 16

A laboratory test that is used to confirm syphilis and detects specific treponemal antibodies is:

A) VDRL
B) MHA-TP
C) RPR
D) monotest

Question 17

A patient is diagnosed with syphilis.Which of the following laboratory tests can be used to monitor the effectiveness of therapy in this patient?

A) RPR
B) MHA-TP
C) C-reactive protein
D) monotest

Question 18

A 25-year-old patient presents with a fine rash on his chest,palms and feet,fever and malaise.The RPR is reactive with a titer of 1:64,the VDRL is non-reactive,and the MHA-TP is positive.What is the diagnosis?

A) primary syphilis
B) secondary syphilis
C) tertiary syphilis
D) latent syphilis

Question 19

At which stage of syphilis is the RPR specific for syphilis?

A) primary
B) secondary
C) tertiary
D) latent
E) none of these

Question 20

A patient has a reactive RPR at a titer of 1:128 and a reactive MHA-TP.What does this indicate for the patient?

A) true-positive diagnosis of syphilis
B) false-positive diagnosis of syphilis
C) true-negative ruling out syphilis
D) false-negative ruling out syphilis

Question 21

Which of the following may characterize the disease process in syphilis?

A) generalized rash
B) period of latency
C) localized chancre
D) all of the above
E) all except one of the above

Question 22

In an indirect fluorescent immunoassay such as the FTA confirmatory test for syphilis,all of the following are true EXCEPT:

A) A labeled antigen is used.
B) Washing is an important step.
C) Patient antibody is detected.
D) Antihuman globulin has a fluorescent tag.

Question 23

Which of the following is a confirmatory test for syphilis?

A) rapid plasma reagin
B) fluorescent antibody (FTA)
C) VDRL
D) all of the above

Question 24

Lab results on a patient indicated a positive RPR and a negative FTA.The patient had no obvious sore,rash,or other symptoms.What is the most likely cause of these results?

A) primary syphilis
B) secondary syphilis
C) tertiary syphilis
D) another disease,such as mono

Question 25

Which best describes the antibody known as reagin?

A) It occurs only in the disease syphilis.
B) It is tested for using charcoal and cardiolipin.
C) It is found in all patients with primary syphilis.
D) It is antibody directed against IgG.

Question 26

Which best describes the antibody called reagin found in syphilis?

A) It reacts with cardiolipin.
B) It is specific for treponemal antigen.
C) It appears in all patients within 7 days after exposure to syphilis.
D) It is detected by the FTA-ABS test.