MCQ on Spirochetes- Treponema spp, Borrelia spp, Leptospira spp (Gram negative, helical shape)

1) Which of the following are not the common morphological characteristics of spirochetes?
a) They are gram-negative helical bacteria
b) They are motile and have periplasmic flagella (endo flagella)
c) They reproduce by transverse binary fusion
d) They are obligate aerobes

2) Which of the following subspecies of Treponema pallidum causes endemic syphilis?
a) Treponema carateum
b) Treponema endemicum
c) Treponema pertenue
d) None of the above

3) The RPR (Rapid Plasma Reagin) is a nontreponemal test method used as a screening test for syphilis, which of the following statements is correct about the test?
a) It is an expensive method
b) It often shows a positive result with primary syphilis
c) It often shows a false positive result for syphilis
d) It is a specific test for Treponema pallidum

4) A 30 year old man infected with syphilis developed a skin lesion on his prepuce, the lesion was oval in shape and painless. What is the specific name for this type of lesion?
a) Nodules
b) Papule
c) Eczema
d) Hard chancre

5) Epidemic Relapsing fever in humans is caused by the infected body louse which acts as a vector and is transmitted to humans, which of the following is the most likely spirochetes?
a) Borrelia recurrentis
b) Leptospira interrogans
c) Borrelia burgdorferi
d) Borrelia hermsii

6) The following pathogen is motile, found worldwide, and infect kidneys and liver which can lead to infectious jaundice, the bacterial serovars are transmitted to humans through contact with animals and their excreta. Name the most likely pathogen
a) Borrelia burgdorferi
b) Bordetella pertusis
c) Leptospira interrogans
d) Enterococcus faecalis

7) Which of the following statements is most correct about the dark field microscopy for the diagnosis of spirochetes?
a) It is used to observe and detect thin spirochetes suspended in a liquid
b) The specimen is stained and detected under the compound microscope
c) The color of the spirochetes appears grey when observed under the dark background
d) It is used to detect the spirochetes from the oral cavity, cerebrospinal fluid

8) Which of the following organisms is NOT commonly found as a part of normal flora in the oral cavity?
a) Streptococcus mutans
b) Borrelia buccalis
c) Spirillum minor
d) Candida albicans

9) What stain is mostly used for the detection of Borrelia spp which causes relapsing fever?
a) Gram stain
b) Ziehl-Neelsen stain
c) Giemsa stain
d) Methylene blue

10) The bacteria causing Leptospirosis are difficult to isolate from urine, blood, or CSF specimens by culture method, therefore a confirmation test should be done. Which of the following statement is most correct in the diagnosis of the disease?
a) RPR tests for the detection of serogroup antigens from the acute or convalescent phase
b) Antibodies are tested against the serogroup antigens from the acute or convalescent phase
c) Darkfield microscopy method is done to detect the pathogen from serum samples
d) All of the above

11) The diagnosis of Lyme disease is done by two serological tests after the screening test, one with a positive confirmatory ELISA test, what is the other test?
a) Western blotting assay
b) PCR
c) Immunofluorescent assay
d) Southern blotting assay

12) Which of the following spirochetes causes skin disease primarily to individuals who have dark skin color and is transmitted by direct contact or vectors such as flies?
a) Borrelia hermsii
b) Spirillum minor
c) Treponema pallidum subspecies pertenue
d) Treponema carateum

13) Which of the following pathogens are the causative organisms of sexually transmitted diseases?
a) Treponema pallidum subspecies endemicum
b) Treponema pallidum subspecies pallidum
c) Borrelia recurrentis
d) Borrelia hermsii

14) Which of the following statements is not correct about congenital syphilis?
a) The spirochetes are transferred from mother to fetus across the placenta
b) The early manifestations occur in children during the birth
c) Five to ten percentages of children develop cutaneous lesions
d) The infection can lead to stillbirth

15) What is the most likely pathogen related to rat-bite fever?
a) Leptospira interrogans
b) Borrelia hermsii
c) Treponema pallidum subspecies endemicum
d) Spirillum minor

Multiple Choice Answers 
1-d) They are obligate aerobes
2-b) Treponema endemicum
3-c) It often shows a false-positive result for syphilis
4-d) Hard chancre
5-a) Borrelia recurrentis
6-a) Borrelia burgdorferi
7-a) It is used to observe and detect thin spirochetes suspended in liquid
8-c) Spirillum minor
9-c) Giemsa stain
10)- b) Antibodies are tested against the serogroup antigens from acute or convalescent phase
11-a) Western blotting assay
12-d) Treponema carateum
13-b) Treponema pallidum subspecies pallidum
14-c) Five to ten percentages of children develop cutaneous lesions
15-d) Spirillum minor

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