Spirochetes Flashcards
Describe the morphology of spirochetes
Spirochetes are gram negative, anaerobic, helically shaped, motile bacteria. They move via corkscrew movement.
Describe the orientation of spirochete flagella
Located in the periplasm between the cytoplasmic and outer membrane, they link the head and tail of the organism and spin to create corkscrew motion
Most spirochetes aren’t human pathogens. What are the 3 major spirochete pathogens and the diseases they cause?
1) Leptospira spp.: cause leptospirosis
2) Treponema pallidum: causes syphilis
3) Borrelia burgdorferi: causes Lyme disease
What is the natural habitat of Leptospira species and in what climate are they found?
Most often found in stagnant fresh water. Can grow at lower temperatures but grow best at tropical temperatures. Usually found in tropical climates but can be found seasonally outside of the tropics
What is the reservoir(s) of Leptospira species?
Leptospirosis is a zoonotic disease and its primary host is rodents but can also infect other wild animals as well as domesticated ones
How does transmission of leptospirosis to humans occur?
Humans can become infected with leptospirosis through contact or ingestion of water contaminated by animal urine. This occur through breaks in the skin or through mucous membranes.
What is important to remember about leptospirosis symptoms and complications?
Leptospirosis has a wide range of possible symptoms and may mimic other diseases, possibly leading to a misdiagnosis. Complications may be life threatening and infection requires prompt and proper diagnosis/treatment.
Why is diagnosis of leptospirosis done with serology and not microscopy or culture?
Microscopy not used because it is very difficult to see spirochetes in tissue
Culture not used because the medium is difficult to make and colonies take months to form
What is the causal organism of syphilis?
Treponema pallidum
Name and descibe the main symptom of primary syphilis
Chancre - painless, non-itchy ulcer up to 3 cm wide
What is the main symptom of secondary syphilis? What distinguishes it from other, similar symptoms?
Rash, variable, may be maculopapular, pustular…
Secondary syphilis involves a rash of the palms and bottoms of feet - not many other rashes do this!
How is latent syphilis defined?
Serological proof of infection WITHOUT symptoms
Name and describe the 3 types of tertiary syphilis?
1) Gummatous: soft, tumor-like balls of inflammation/lesions
2) Neurosyphilis: general paresis, tabes dorsalis (loss of coordination of movement)
3) cardiosyphilis
What are the 2 ways syphilis is transmitted?
Sexual and vertical
How is syphilis treated?
Intramuscular or intravascular penicillin
What is the mainstay of syphilis (and other pathogenic spirochete) diagnosis?
SEROLOGY
There are 2 types of syphilis serologic tests, treponemal and non-treponemal. Describe the non-treponemal test
Non-treponemal test is a agglutination test. The treponemes induce damage to host cells and anti-cardiolipin antibodies (non-anti-treponemal Ig) are produced. The antibodies interact with lecithin-cholesterol-cardiolipin (liposomes) causing agglutination that will trap charcoal in the lattice
What are the disadvantages and advantages of non-treponemal serology?
Disadvantages: insensitive early and late in disease, false positives may occur (lyme, lymphoma etc.)
Advantages: rapid, inexpensive, easy, used to follow response to therapy
Name the 2 treponemal serologic tests. What do they all measure?
The treponemal serologic tests measure antibody produced against Treponema pallidum antigens
1) Fluorescent treponemal antibody absorbed
2) T pallidum particle agglutination
What is the advantage and disadvantages of treponemal serologic tests?
Advantage: reactive for life
Disadvantage: false positives or negatives may occur
