Chapter 21: Spirochete Diseases

Question 1

Syphilis

Answer 1

○ A sexually transmitted disease caused by the spirochete bacterium Treponema pallidum
○ Direct contact with open lesion needed
○ Transmission to fetus during pregnancy

Question 2

What are the stages of syphilis?

Answer 2

○ Primary: Development of chancre
○ Secondary: lymphadenopathy, malaise, fever, pharyngitis, rash
○ Latent: Asymptomatic
○ Tertiary: Gummatous, cardiovascular, neurosyphilis

Question 3

How is syphilis treated?

Answer 3

Effectively treated with antibiotics (e.g., penicillin) when detected in the early stages

Question 4

What is congenital Syphilis?

Answer 4

○ Transmission of treponemes to the fetus occurs when pregnant woman has early-stage or latent syphilis
○ Causes death in 10% of cases

Question 5

Nontreponemal Tests

Answer 5

○ Detect antibody against cardiolipin (reagin)
○ a lipid released from membranes of cells damaged as a result of the infection

Question 6

What are examples of nontreponemal tests?

Answer 6

○ Venereal Disease Research Laboratory (VDRL) test
○ Rapid plasma reagin (RPR) test

Question 7

Venereal Disease Research Laboratory (VDRL) test

Answer 7

○ Patient serum mixed on slide with cardiolipin lecithin-cholesterol antigen suspension
○ Rotated for 4 minutes at 180 rpm
○ Viewed under light microscope for flocculation

Question 8

VDRL test results

Answer 8

○ Reactive = medium to large clumps
○ Weakly reactive = small clumps
○ Nonreactive = no clumps or slight roughness

Question 9

RPR Test

Answer 9

○ Patient serum mixed on card with charcoal particles coated with cardiolipin antigen
○ Rotate 8 minutes, 100 rpm
Observe for macroscopic flocculation

Question 10

What is the purpose of treponemal tests?

Answer 10

Detect antibody to T pallidum

Question 11

What are some examples of treponemal tests?

Answer 11

○ Fluorescent treponemal absorption (FTA-ABS)
○ T pallidum particle agglutination (TP-PA)
○ Automated immunoassays: like ELISA

Question 12

FTA-ABS Test

Answer 12

An indirect immunofluorescence test for antibody to T pallidum

Question 13

TP-PA Test

Answer 13

○ Patient serum and controls diluted and incubated with unsensitized gel particles or gel particles sensitized with T pallidum antigen
○ Resutls: += agglutination, -= no agglutination

Question 14

Special Diagnostic Areas for T. pallidum

Answer 14

○ Molecular testing for T pallidum DNA
○ Patient monitoring: Titers decline with successful treatment
○ Congenital syphilis: Perform nontreponemal tests on mother and infant at birth and IgM-specific treponemal assays to confirm
○ Neurosyphilis: Perform VDRL or ELISA on cerebrospinal fluid

Question 15

Lyme Disease

Answer 15

○ Caused by the spirochete bacterium Borrelia burgdorferi
○ Transmitted by Ixodes ticks
○ Main reservoir: the white-footed mouse

Question 16

What are the stages of Lyme disease?

Answer 16

○ Stage 1: Localized rash (bullseye shaped rash)
○ Stage 2: Early dissemination
○ Stage 3: Late dissemination with arthritis

Question 17

How is Lyme disease diagnosed?

Answer 17

○ Screen with immuno fluorescence immunoassay (IFA) or ELISA for antibodies:: Antibodies may not appear until 3 to 6 weeks after tick bite
○ Confirm with Western blot

Question 18

Relapsing Fever

Answer 18

○ Caused by Borrelia miyamotoi
○ Transmitted by Ixodes ticks
○ Causes flu-like illness, skin rash

Question 19

How is relapsing fever diagnosed?

Answer 19

○ ELISA for antibodies to B miyamotoi proteins
○ PCR may be used in the future