Spirochetes

Question 1

What is a spirochete?

Answer 1

Unusual anaerobic gram -ve

Thin and spiral shaped w/ many plasmid and varied genome size

Question 2

How identify spirochete?

Answer 2

Use dark field microscopy - difficult to stain

Question 3

How are spirochetes mobile? and evidence?

Answer 3

Internal flagellum - counter-rotation resulting in rotation of body and burrowing motility
Deletion of flagella assembly gene (flaB, flaE) cause aflagellate non-motile strain

Question 4

What is on cell surface spirochetes and what to they do?

Answer 4

Msp protein - major sheath protein - modulate immune response

Question 5

What causes Lyme disease?

Answer 5

Borrelia burgdoferi (zoonotic infection)

Question 6

How do you get Lyme disease?

Answer 6

Transmission via ticks - transmitted via saliva from biting humans

Question 7

3 life cycle stage of infection - Lyme disease?

Answer 7

Acute: characteristic bulls eye rash (other lesions distant from site in 50% pt) w/ flu like symptoms

Later infection - seen 1 week - 2 years- caused when bacteria enter site other than blood stream

• Neurological symptoms: meningitis, peripheral neuropathy
• Cardiac- myocarditis
• Arthiritis

Question 8

Prevention and tx borrelia infection

Answer 8

Ab: doxycycline
Vaccine: OspA (surface protein) - only partially effective as OspA not expressed in human borrelia
Prevention: long socks, avoidance endemic area, DEET

Question 9

Why are chronic borrelia infection hard to tx?

Answer 9

Become metabolically inert and reside in sites refractory to tx

Question 10

What is relapsing fever?

Answer 10

Borrelia recurrentis - repeated febrile illness - initial infection cleared - antigenic variation start new set of symptoms

Question 11

Relapsing fever - what causes antigenic variation?

Answer 11

OspC surface protein - expressed variably

Question 12

How do you get Weils disease?

Answer 12

zoonotic recevoir (dogs and rat urine) is stagnant water which enters via broken skin

Question 13

Symptoms of Weils disease?

Answer 13

Febrile, flu like illness
Reddening of eye
Worse case: kidney and liver failure

Question 14

Prevention Weils

Answer 14

Prevent: rodent control, avoid swimming infected river

Question 15

Example oral spirochetes?

Answer 15

1. Treponema vincentii - cause trench mouth - tx metronidazole/ hydrogen peroxide
2. Treponema denticola - red complex causes periodontitis

Question 16

Virulence treponema denticola?

Answer 16

Adherence to basement membrane 
Proteases 
Sialidases
Motility 
Co-adherence other bacteria