Systemic Spirochetes Flashcards
Spirochete
Giemsa & Silver Stains
Microaerophilic
Borrelia
Vector for Borrelia burgdoferi
1 Vector-Borne Disease in the U.S.
Ixodes tick (deer ticks)
Reservoir = deer and mice
Is lyme disease found throughout the U.S.?
No, it is most often found in the NE and Midwest (esp., Great Lake Region)
Stages of Lyme Disease
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)
Pathobiology of Lyme Disease
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
Lab tests for Lyme Disease
Two-Tiered Test
ELISA/IFA
+
Western Blot
When is the best time to treat Lyme Disease and with what?
During Stage 1
Doxycline or Amoxicillin for children under 8
(Later stages treat with ceftriaxone IV)
Patient presents with symptoms of Lyme Disease (Stage 1) and is given doxycycline. They come back after not getting better. What is going on?
Possible co-infection with Babesia
Both Borrelia and Babesia are carried by the Ixodes tick
Look for maltese cross
Treat with clindamycin or quinine
STARI
Southen Tick-Associated Rush Illness
Similar disease to Lyme, but caused by lone star tick (Amblyomma americanum)
What causes Relapsing Fever?
Borrelia recurrentis (epidemic)
Borrelia hermsii (endemic)
“recurring all around the world” vs “hermitting in one place”
Pathobiology of Relapsing Fever caused by B. recurrentis
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)
Which is the only Borrelia species to be spread by lice
Borrelia recurrentis
Borrelia hermsii, and other Borrelia are spread by ticks
Which tick is Borrelia hermsii spread by?
Soft-Shelled tick (Ornithodoros)
Unlike B. recurrentis (no animal reservoir), B. hermsii has a rodent reservoir
Dx of Relapsing Fever
Blood sample and Culture during fevers
Spirochete, motile under dark-field microscopy
Tx for Relapsing Fever
Penicillin or Tetracycline
NOTE: treatment may lead to Jarisch-Herxheimer rxn (lysis of treponeme = release of endotoxin-like factors = fever, chills, and myalgias)
Where does antigenic variation occur?
In the outer membrane, specifically with VMP (Variable Major Protein)
What spirochete should you be worried about after wading through water that is contaminated with animal urine?
Leptospira interrogans
Acute Febrile Illness
Conjuctival Suffusion (reddening)
Jaundice + Renal Failure
Leptospira interrogans
Jaundice + Renal Failure = Weil disease
Monitor for meningitis and treat with Doxycycline (chemoprophylaxis)
Jaundice + CNS involvement
Borrelia recurrentis
or
Leptospira interrogans (look for “question-marked shape” on gram stain)
Interroga**tion: want answers to **questions
Spirochete that cannot be grown in vitro
T. pallidum
Key words:
Chancre (Primary)
Maculopapular Rash (Secondary)
Tabes Dorsalis (Tertiary)
Aortitis and Gummas (Tertiary)
Animal urine
Leptospira interrogans
OR
Hantavirus
Rash on Palms and Soles
“You drive Kawasaki CARS (in this instance car = motorcycle) with your hands and feet”
Kawasaki Disease
Cox A
RMSF
Secondary Syphilis
Monoarthritis in the knee
Stage 3 lyme disease
