Systemic Spirochetes

Question 1

Spirochete

Giemsa & Silver Stains

Microaerophilic

Answer 1

Borrelia

Question 2

Vector for Borrelia burgdoferi

Answer 2

1 Vector-Borne Disease in the U.S.

Ixodes tick (deer ticks)

Reservoir = deer and mice

Question 3

Is lyme disease found throughout the U.S.?

Answer 3

No, it is most often found in the NE and Midwest (esp., Great Lake Region)

Question 4

Stages of Lyme Disease

Answer 4

Inoculation (2-7 days): tick needs at least 24 hrs to transmit sufficient inoculum, allowing spread into the dermis

Stage 1: erythema chronicum migrans (localized infection, days to weeks after bite)

Stage 2: disseminated infection weeks to months after bite

CNS: BILATERAL Bell’s Palsy, aseptic meningitis, peripheral neuropathy

CV**: carditis, **AV nodal block

• Skin: secondary annular lesions*
• Joints: migratory myalgias, transient arthritis*

Stage 3: persistent infection months to years after bite

Chronic arthritis; encephalopathy; acrodermatitis chronicum atrophicans (widespread skin atrophy)

Question 5

Pathobiology of Lyme Disease

Answer 5

Stage 1: at inoculation site, bacteria multiply and migrate outward; generate a spreading annular red lesion surrounding clear bite mark; flu-like symptoms

Stage 2: disseminated spirochetes proliferate; inflammatory response damages CNS, heart, skin, and joints

Stage 3: persistent infection; inflammatory damage in joints, brain, and local areas of skin atrophy

Question 6

Lab tests for Lyme Disease

Answer 6

Two-Tiered Test

ELISA/IFA

+

Western Blot

Question 7

When is the best time to treat Lyme Disease and with what?

Answer 7

During Stage 1

Doxycline or Amoxicillin for children under 8

(Later stages treat with ceftriaxone IV)

Question 8

Patient presents with symptoms of Lyme Disease (Stage 1) and is given doxycycline. They come back after not getting better. What is going on?

Answer 8

Possible co-infection with Babesia

Both Borrelia and Babesia are carried by the Ixodes tick

Look for maltese cross

Treat with clindamycin or quinine

Question 9

STARI

Answer 9

Southen Tick-Associated Rush Illness

Similar disease to Lyme, but caused by lone star tick (Amblyomma americanum)

Question 10

What causes Relapsing Fever?

Answer 10

Borrelia recurrentis (epidemic)

Borrelia hermsii (endemic)

“recurring all around the world” vs “hermitting in one place”

Question 11

Pathobiology of Relapsing Fever caused by B. recurrentis

Answer 11

Human is the ONLY HOST

Human to human transmission by body louse; enter bloodstream and multiply; trigger host inflammatory response and fever; most bacteria killed

antigenic variation of outer membrane proteins by rearrangement and expression of silent genes; new antigenic type multiplies; stimulates new immune response; relapse of fever

5 days febrile / 8 days afebrile (repeats up to 10 times)

Question 12

Which is the only Borrelia species to be spread by lice

Answer 12

Borrelia recurrentis

Borrelia hermsii, and other Borrelia are spread by ticks

Question 13

Which tick is Borrelia hermsii spread by?

Answer 13

Soft-Shelled tick (Ornithodoros)

Unlike B. recurrentis (no animal reservoir), B. hermsii has a rodent reservoir

Question 14

Dx of Relapsing Fever

Answer 14

Blood sample and Culture during fevers

Spirochete, motile under dark-field microscopy

Question 15

Tx for Relapsing Fever

Answer 15

Penicillin or Tetracycline

NOTE: treatment may lead to Jarisch-Herxheimer rxn (lysis of treponeme = release of endotoxin-like factors = fever, chills, and myalgias)

Question 16

Where does antigenic variation occur?

Answer 16

In the outer membrane, specifically with VMP (Variable Major Protein)

Question 17

What spirochete should you be worried about after wading through water that is contaminated with animal urine?

Answer 17

Leptospira interrogans

Question 18

Acute Febrile Illness

Conjuctival Suffusion (reddening)

Jaundice + Renal Failure

Answer 18

Leptospira interrogans

Jaundice + Renal Failure = Weil disease

Monitor for meningitis and treat with Doxycycline (chemoprophylaxis)

Question 19

Jaundice + CNS involvement

Answer 19

Borrelia recurrentis

or

Leptospira interrogans (look for “question-marked shape” on gram stain)

Interroga**tion: want answers to **questions

Question 20

Spirochete that cannot be grown in vitro

Answer 20

T. pallidum

Key words:

Chancre (Primary)

Maculopapular Rash (Secondary)

Tabes Dorsalis (Tertiary)

Aortitis and Gummas (Tertiary)

Question 21

Animal urine

Answer 21

Leptospira interrogans

OR

Hantavirus

Question 22

Rash on Palms and Soles

Answer 22

“You drive Kawasaki CARS (in this instance car = motorcycle) with your hands and feet”

Kawasaki Disease

Cox A

RMSF

Secondary Syphilis

Question 23

Monoarthritis in the knee

Answer 23

Stage 3 lyme disease