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Chapter 13: Spirochetes


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What are the three genera of spirochetes?
Treponema, Borrelia, and Leptospira
Treponema produces no toxins or tissue destructive enzymes – how does it cause disease?
The host’s own immune responses – inflammatory cell infiltrates, proliferative vascular changes, and granuloma formation.
Describe primary syphilis?
Painless chancre that erupts at the site of inoculation up to 6 weeks after the initial contact – highly infectious. This resolves over the next 6 weeks.
Describe secondary syphilis?
Bacteremic stage occurs approx. 6 weeks after the chancre has healed. Systemic – widespread rash, lymphadenopathy, multi organ involvement. Also, conyloma latum – lesion occurs in warm, moist sites.
What is latent syphilis?
If gone untreated, features of secondary syphilis will resolve, but latency will continue for several years, often including relapses.
Describe the three components of tertiary syphilis?
1. Gummatous syphilis – granulomatous lesions which eventually necrose
2. Cardiovascular syphilis – ie. aortic aneurism
3. Neurosyphilis – subacute meningitis (predominance of lymphocytes), meningovascular syphilis, tabes dorsalis, general paresis of the insane. Sometimes neurosyphilis is asymptomatic.
What is the Argyll-Robertson pupil?
Like the prostitute with syphilis, it “accommodates but does not react.” Caused by the midbrain lesion in tabes dorsalis and general paresis.
Rule of sixes in syphilis?
See page 93
What is the treatment of choice for syphilis?
Penicillin – which can even cross the placenta and cure congenital syphilis.
Describe Treponema pallidum subspecies pertenue?
Yaws – a disease of the moist tropics – tertiary lesions can cause disfigurement of the face.
Describe Treponema pallidum subspecies carateum?
Pinta – skin disease limited to rural Latin America.
What is the most commonly reported tick-borne illness in the US and what bug causes it?
Lyme disease caused by Borrelia burgdorferi – Ixodes tick.
Describe similarities between Lyme disease and syphilis?
Both are caused by spirochetes.
Both have a primary stage involving a single painless skin lesion.
Both involve spread throughout the body, with multiple organ involvement.
Both cause chronic problems years later.
What is the skin lesion of Lyme disease called?
Erythema chronicum migrans.
To which 4 organ systems do Borrelia spirochetes disseminate in early stages?
Skin, nervous system, heart, and joints.
What antibx are used to treat Lyme disease?
Penicillin or doxycycline.
What bug causes relapsing fever? How does it cause relapses?
Borrelia recurrentis. Antigenic variation involves the rapid change of surface proteins, so the bug is unrecognizable by antibodies.
Where can leptospira be found (reservoir)?
Urine of dogs, rats, livestock, and wild animals.
Describe the first leptospiremic phase?
Invasion of blood and CSF, with fever, headache, muscle aches. Classical signs – red conjunctiva and photophobia.
What is Weil’s disease? What causes it?
Infectious jaundice caused by a Leptospira species.

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