Spirochetes

Question 1

List the common spirochetes (3)

Answer 1

Borrelia burgdorferi
Leptospira interrogans
Treponema pallidum

Question 2

What disease is caused by Borrelia?

Answer 2

Lyme Disease

Question 3

Where is Lyme Disease typically found?

Answer 3

NE United States (NH, CT especially)

Pts have usually just returned from hiking/camping in forest

Question 4

What is the vector for Lyme Disease?

Answer 4

Ticks - Ixodes scapularis

Question 5

What 3 diseases are caused by the Ixodes tick?

Answer 5

Lyme Disease, Ehrlichiosis, Bibessiosis

Question 6

What is the main reservoir for Lyme Disease?

Answer 6

White-footed mouse. Tick’s larvae feast on white-footed mouse (reservoir). Adult ticks feast on white-tailed deer (obligating host). Humans are an incidental host.

Question 7

What do spirochetes look like on gram stain?

Answer 7

They do not gram stain due to thin cell walls.

Question 8

How do you visualize Borrelia?

Answer 8

Light microscope (only Spirochete that you can do this with)

Use Wright Stain or Giemsa Stain.

Question 9

Lyme Disease symptoms

Answer 9

Stage 1:

Rash called erythema chronica migrans (“bull’s eye rash”)
Not painful. Not pruritic. Usually occurs within 1 month of tick bite.

Rash is accompanied by flu-like symptoms (fever, chills)

Stage 2:

Heart block caused by myocarditis
Bilateral facial nerve palsy (Bell’s palsy)

Stage 3:

Arthritis of large joints (knee)
Migratory polyarthritis (moves btw different large joints)
Memory difficulty, encephalopathy

Question 10

Lyme Disease Tx

Answer 10

Start as early as possible (ideally stage 1)

Stage 1: Doxycycline

Stages 2-3: Cephtriaxone

Question 11

What does Leptospira look like?

Answer 11

Question mark shaped or spiral

Question 12

What part of the USA sees the highest incidence of leptospirosis?

Answer 12

Hawai’i

It is endemic to tropical regions

Question 13

Leptospira transmission

Answer 13

Found in animals like rodents or dogs and excreted in their urine.

Transmitted to humans when we swim in the contaminated water - associated with watersports.

Question 14

Leptospirosis symptoms

Answer 14

Early manifestation includes fever with intense HA.

Also, conjunctival suffusion - even though there is diffuse reddening of the eyes, there’s a lack of inflammatory exudate (red w/o the pus)

Systemic infection is known as leptospirosis. In most severe form, it’s known as Weil’s Disease.

Travels through blood and can multiply in various organs:

Renal dysfunction - fever high creatinine, azotemia in a young person who does watersports

Jaundice from liver damage

Question 15

What disease does Treponema cause?

Answer 15

Syphilis - “The Great Imitator” bc many symptoms looks like other diseases.

Question 16

What does syphilis look like?

Answer 16

Spiral shaped

Question 17

How do you visualize syphilis?

Answer 17

Darkfield microscopy.

Must take direct sample from a lesion. It’s not the most commonly used bc most labs aren’t set up for it. Instead, we do blood tests.

Question 18

How do you diagnose syphilis?

Answer 18

Blood tests.

VDRL (Venereal Disease Research Lab) is screening test for treponema. It is a non-treponemal test (not specific for t.pallidum). It just tests for antibody reactivity in patient serum to a particular antigen called cardiolipin-cholesterol-lecithin antigen.

RPR (rapid plasmin reagent) is another screening test. We use both of these to screen in patients with symptoms or who are at high risk.

High levels of false positives though due to cross-reactivity with other antigens. Mono, RF, SLE, Leprosy, IV drug users.

All these false positives - we need a test to confirm!

FTA-Antibody Test:

This is a tremonemal test (directly looks for t. pallidum). It is specific to confirm positive activity from screening tests.

Summary: Do VDRL or RPR and confirm with FTA-Antibody

Question 19

What other conditions may cause a positive syphilis screening test (VDRL or RPR)

Answer 19

Mono, Rheumatic Fever, SLE, Leprosy, IV drug users

Question 20

Primary Syphilis

Answer 20

Characterized by painless genital chancre appearing a few weeks after inoculation

Causes chancre by locally invading small blood vessels and damaging them. This leads to small areas of ischemic necrosis, producing the chancre. Ischemia also knocks out the nerves so it is painless.

Chancre will heal in 3-6 weeks, but if left untreated it will progress to secondary stage.

Question 21

Secondary syphilis

Answer 21

Systemic disease - no longer localized to genitals

Maculopapular rash on palms and soles weeks to months after infection. The rash appears everywhere since it is systemic but the palms/soles are unique.

May see condyloma latum on mucous membranes - flat-topped papule instead of warty growth in HPV (condyloma acuminatum)

You can visualize the spirochetes within the condyloma latum via darkfield microscopy

Question 22

Tertiary Syphilis

Answer 22

Formation of Gummas - soft growths with firm necrotic center - can occur anywhere (skin, internal organs, bone)

Aortitis of thoracic aorta (ascending) which can lead to an ascending thoracic aneurysm

Aorta shows tree-barking on pathology. Syphilis destroys the vaso-vasorum (vessels that supply thick wall of aorta). This weakens aortic wall and leads to aneurysm

Tabes dorsalis - demyelination of nerves in dorsal column/posterior column of spinal cord leading to loss of vibration sense, proprioception, and discriminative touch.

TD also causes lancetating pain all over and odd gait from loss of proprioception

We can also see some ocular effects. Neuronal damage leads to Argyll Robertson pupils - Prostitute’s Pupil - pupils accommodate, but do NOT react to light.

Question 23

Congenital Syphilis

Answer 23

May see this in developing countries (it is standard to screen pregnant women in US)

Presents with constellation of symptoms:

1) Saber shins - anterior bowing of tibia
2) Saddle nose - stubby nose with indented bridge
3) Hutchinson’s teeth (notched incisors) and Mulberry Molars (Molars with several enamel outgrowths)
4) Deafness

You can also see hepatomegaly, rhinitis, and rash at birth

Question 24

Syphilis Tx

Answer 24

Penicillin in every stage in everyone

If you’re allergic, tetracyclines but you should try to desensitize them and use penicillin anyway (ESP if pregnant - tetracyclines aren’t that great for pregnancy)

Jarish-Herxheimer Rxn - may occur hours after Tx. Dying spirochetes release a bunch of LPS that causes an increase in cytokines and leads to fever, chills, HA.