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Endocrine and Reproductive Systems > M- Syphilis and Treponemal Infections > Flashcards

M- Syphilis and Treponemal Infections Flashcards

1
Q

What are the microbiological features of treponema pallidum [syphilis]?

A
  1. highly motile - periplasmic endoflagella wedged between cytoplasmic membrane and outer membrane
  2. slender, long, helical organism
  3. NO LPS despite the 2 membranes and peptidoglycan is linked to the the CM so it cannot gram stain
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2
Q

What is unique about cuturing treponema in the lab?

A

It cannot be cultivated in vitro!

It must be cultivated using rabbits [similar to how leprosy is cultured on the footpads of 9-banded armadillos]

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3
Q

Treponema are associated with what 2 things?

A
  1. syphilis- sexually transmitted

2. non-venereal treponematoses [yaw, pinta, Bejel endemic syphilis] - spread person to person and on fomites

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4
Q

What is responsible for most of the clinical manifestations of treponema infections?

A

The host immune response [acute and chronic inflammation] in response to the lipoproteins on T. pallidum

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5
Q

What is the reservoir for syphilis?
How is it transmitted?
What is the relationship between syphilis and HIV?

A

Syphilis is exclusively a human disease.

Mainly venereal transmission but also:
kissing, transfusion, oral sex, breast milk, transplacental.

If someone has syphilitic ulcers, there is an increased risk to both give and receive HIV.

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6
Q

Describe the pathogenesis of syphilis.

A
  1. penetrates abraded skin, deposits in the dermal tissue and replicates.
    [a small inoculum size can est. infection
  2. Systemic dissemination occurs because the treponema go through the tight junctions of capillaries and enter the bloodstream
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7
Q

What is the incubation period of syphilis?

A

3-8 wks

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8
Q

What stages of syphilis have dark field microscopy positive for spirochetes?

A

Primary, secondary and secondary recurrences

There are no serum spirochetes in latency!!!

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9
Q

A patient presents with a firm, well-demarcated, indurated chancre. It is painless. What is the likely cause? What stage of the disease is it?

A

primary syphilis

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10
Q

Between primary and secondary stages of syphilis, what happens?
How long is this interval?

A

The syphilis heals w/o treatment.

The time between primary and secondary can be anywhere from 6wks to 6months

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11
Q

When in the course of untreated syphilis does secondary stage typically occur?
How does it manifest ?

A

Secondary syphilis usually occurs within 6 months of infection.
There are diverse [protean] presentations but >90% have some form of rash. It will typically involve the palms and soles.

Syphilis in second stage also mimics other disorders giving it the name “the great imitator”

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12
Q

If patients go untreated from secondary syphilis, what are the 3 courses the disease can take?

A

1/3 –>spontaneous resolve
1/3 –> stay in latency
1/3 –> progress to tertiary syphilis

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13
Q

What occurs during tertiary syphilis?

A
  1. benign gummas [destructive, granulomatous lesions of skin, bone, and viscera].
    * spirochetes are rarely if ever found in lesions
  2. cardiovascular [thoracic aortic aneurysm]
  3. neurosyphilis - dementia, erratic behavior, etc
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14
Q

When is a person with syphilis infectious to others?

A

Soon after inoculation to early latency [however, it depends on the disease manifestations and mode of contact]

Late latency and tertiary infections are NOT infectious

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15
Q

What causes congenital syphilis?

A

Transplacental transmission in the first trimester (after 18 weeks gestation) om women who have been infected for less than 2 years [still in early latency]

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16
Q

In terms of days, months, years, when does primary, secondary, early latency, late latency and tertiary syphilis usually occur?

A

Primary - 10 to 90 days [3 to 8 weeks]
Interval between 1 and 2 = 6wks to 6months
Early latency lasts until about 2 years after infection.
Late latency is from 2 years onward

17
Q

What accounts for the majority of symptoms for ALL stages of syphilis?
What virulence factor of T. pallidum has been implicated?

A

The host’s overlapping acute and chronic inflammation accounts for the majority of symptoms.
The organisms lipoproteins have been implicated as the principal pro-inflammatory mediator during disease pathogenesis

18
Q

What is meant when they say T. pallidum is a “stealth pathogen”?

A

Infection by T. pallidum causes a strong Ab response [specific AND nonspecific], however, the Ab play no role in protective immunity because T. pallidum displays the lipoproteins [the major immunogen] on the cytoplasmic inner membrane and not the outer membrane.

Therefore, Ab are made in extremely high titer, but they cannot recognize the bacteria

19
Q

Can patients acquire syphilis more than once?

A

Yes because there is no protective immunity elicited by early infections and there is no vaccine

20
Q

How is the diagnosis of syphilis made?

A
  1. visualization of T. pallidum on dark field microscopy from samples taken from the chancre in primary or lesions in secondary
  2. Serology
    - nontreponemal/nonspecific titers of RPR and VDLR that measure anti-cardiolipin Ab
    - treponemal/specific tests - MHA-TP, FTA-ABS, TP-PA which recognize T. pallidum lipoproteins
  3. biopsy - silver stain will show perivascular B-cell lymphocytes with plasma cells
21
Q

Describe the 2 steps of obtaining serology for syphilis.
Which step is non-specific? Specific?
Which titer decreases over the course of late latency and which remains elevated?
What does each titer give you information about?

A
  1. Non-treponemal [RPR, VDRL]
    - non-specific
    - anti-cardiolipin Ab [cardiolipin made by treponema]
    - serum titers are for screening and to track disease progression [rising titer] or after antimicrobial therapy [falling titer]
    - levels fall over the course of late latency
  2. Treponemal [FTA-ABS, MHA-TP, TP-PA]
    - specific because they react to T. pallidum lipoproteins
    - denote present OR PAST infection
    - titer remains elevated for life
    - cannot distinguish reactive from non-reactive
22
Q

What can give false positive VDRL?

A
  1. Autoimmune disease
  2. pregnancy
  3. cancer

[all will have non-reactive specific tests]

23
Q

How is congenital syphilis diagnosed?
How is it treated?
What are the complications if it is not treated?

A

50% of infants are asymptomatic at birth.
Routine serological tests are NOT helpful because they detect maternal IgG that crossed the placenta

Measure fetal IgM directed against specific antigens [lipoproteins] which can be an important adjunct to diagnosis

Treatment: IV penicillin for 14 days

If untreated:
"little old man with potbelly"
-hepatosplenomegaly
- long bones are saber shaped
- nasal streaming filled with spirochetes
-aged facial features
24
Q

What is the most effective treatment against syphilis?
What is an acceptable alternative for early syphilis [except in kids under 8]?
What do you do if there is an allergy to the drug?

How does treatment change when it is neurosyphilis?

A

IM injection of penicillin is most effective.

Tetracycline can be an acceptable alternative, but penicillin is by and large the best.

If the patient has a penicillin allergy, desensitize them.

Neurosyphilis –> IV at higher doses

25
Q

What is the most severe complication of penicillin treatment of syphilis?

A

The Jarisch-Herxheimer reaction can occur within several hours of treatment for primary or secondary syphilis.
Antibiotics kill the T. pallidum which releases the lipoproteins stimulating cytokine cascade {TNFa}.

It manifests as:
Fever, flushing, tachycardia, vasomotor instability, and can be life threatening.

Treat with anti-TNFa

26
Q 
What is Yaws?
Where is it endemic?
How is it transmitted?
How does it present?
How is it diagnosed?
What is treatment?
A 
T. pallidum subspecies pertenue.
It is significant in Africa and Asia. 
Transmission: skin inoculation 
Presentation: 
-stages like syphilis but never attacks CNS
[skin, bones, cartilage]

Dx: dark field, serology, clinical
Rx: penicillin or tetracycline

27
Q

What is the cause of pinta?
Where is it endemic?
How does it present?
Dx? Rx?

A 
It is caused by T. carateum
Endemic to Central and South America
It presents with skin manifestations only.
Dx: dark field, serology, clinical 
Rx. penicillin, tetracycline

Endocrine and Reproductive Systems (27 decks)

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