Micro: Borrelia & Leptospira

Question 1

What is the basic structure of spirochetes?

Answer 1

dual membrane w endoflagella in periplasmic space

no gram stain

Question 2

What are the 3 basic spirochetes and their diseases?

Answer 2

treponema - syphilis, yaws, pinta
borrelia - lyme dz and relapsing fevers
leptospira - leptospirosis

Question 3

What are the general characteristics of spirochete diseases?

Answer 3

cause widely disseminated, often chronic dz (predilection for CNS)
complex dzs often occur in stages
host immune response responsible for clinical manifestations

Question 4

What is the epidemiology of lyme dz?

Answer 4

transmitted by Ixodes (hard) ticks

zoonosis that can infect domestic animals

Question 5

What are the manifestations of lyme dz?

Answer 5

stage 1: erythema migrans and constitutional symptoms
stage 2: CNS (numbness, stiff neck, facial muscle paralysis) heart (heart block)
stage 3: joint swelling and pain

Question 6

How is lyme dz diagnosed?

Answer 6

B. burgdorferi rarely recovered from clinical specimens
pts w erythema migrans often seronegative
other forms require serologic confirmation (ELISA plus immunoblot)
PCR on joint fluid as adjunct

Question 7

How is lyme dz treated?

Answer 7

orally - doxy, amoxil

IV ceftriaxone for severe refractory

Question 8

What is post lyme dz syndrome?

Answer 8

pts remain symptomatic after appropriate therapy

persistent inf, autoimmune rxn, psychological factors?

Question 9

What is the prophylaxis for lyme dz?

Answer 9

antibiotic prophylaxis of tick bites not cost-effective
no vaccine available
minimize risk

Question 10

How is borrelia burgdorferi maintained in nature?

Answer 10

2 year enzootic life cycle involving ticks and small rodents

Question 11

What is the epidemiology of relapsing fevers?

Answer 11

all arthropod-borne (ticks or lice)
EPIDEMIC caused by B. recurrentis on human body louse, severe and can be lethal, inf from crushing louse into wound itching not bite itself
ENDEMIC from soft ticks, animal reservoirs, milder dz

Question 12

What is a key feature in the pathogenesis of relapsing fever?

Answer 12

antigenic variation

Question 13

What is the clinical presentation of relapsing fevers?

Answer 13

acute onset, flu-like symptoms
conjunctival suffusion, petechiae, hepatosplenomegaly
CNS in 1/3 of pts
death from myocarditis, shock, hepatic failure (40% of untreated)

Question 14

How is relapsing fever diagnosed?

Answer 14

demo organisms in peripheral blood smear

serology not helpful

Question 15

What is the treatment of relapsing fever?

Answer 15

tetracycline, erythromycin, or penicillin

Question 16

What is the Jarisch-Herxheimer rxn?

Answer 16

due to cytokine cascade following release of spirochetal contents
sudden high fever, flushing, vasomotor instability, tachy
can be fatal
passive admin of anti-TNF alpha may diminish

Question 17

What is the epidemiology of leptospirosis?

Answer 17

animal reservoirs, transmitted by organisms excreted in urine
risk derived from occupational, military, recreational exposure

Question 18

What is the clinical presentation of leptospirosis?

Answer 18

biphasic illness
initial phase = leptospiremic = flu-like
second = immune - caused by IgM immune complexes
both phases can present in 2 forms
anicteric - aseptic meningitis, uveitis, rash, conjunctival suffusion
icteric - hepatic and renal dysfxn (ATN), myocarditis, vascular collapse (Weil’s dz)

Question 19

How is leptospirosis diagnosed?

Answer 19

culture from blood during first 7-10 days, after only urine, special culture media
serology - 4 fold rise in agglutination titer or titer >1:100

Question 20

What is the treatment and prevention of leptospirosis?

Answer 20

oral doxy can prevent in endemic areas
IV amp, pen, ceftriaxone, tetracycline for tx
supportive therapy
vaccination of livestock/pets, rat control