Spirochetes Flashcards
What are the three genera of spirochetes?
-Treponema -Borrelia -Leptospira
What organism causes syphilis?
-Treponema pallidum
Why can’t we see Treponema pallidum on light microscopy? What kind of microscopy is needed to see them?
-they are too narrow -Need darkfield microscopy or EM
What is the outermost amorphous layer of Treponema pallidum?
-Glycosaminoglycans
What diagnostic tests do we use to detect Treponema pallidum?
Non-treponemal antibody tests: -VDRL (venereal disease research lab of CDC) -RPR (Rapid Plasma Reagin) Treponemal antibody tests: -MHA-TP (MIcrohemagglutination antibody to T. pallidum) -EIA (Enzyme immunoassay)
Where does Treponema pallidum get phosphatidylcholine?
-can’t make its own -takes it from mammalian host =cardiolipin
What tests detect cardolipin in Treponema pallidum?
=non-treponemal antibody tests -VDRL test (venereal disease research laboratory) -RPR (rapid plasma reagin test)
What is the epidemiology of Treponema pallidum?
-Natural spread only among humans -Sexual transmission
What disease does Treponema pallidum cause?
Syphilis
What is weird about the flagella of spirochetes?
They are located underneath the outer membrane
What is the first sign of syphilis?
Primary syphilis = lesion called chancre -incubation of 7-21 days before papule appears
Why is primary syphilis harder to detect in women and homosexual men?
-chancre often in vaginal canal or rectum -syphilis usually diagnosed in second stage
What happens to the primary syphilis chancre without treatment?
-Disappears in 3-4 weeks -reflects development of some immunity
What is secondary syphilis?
-organisms have disseminated widely throughout body -Lesions appear all over skin, truck>extremitis and **involves palms of the hands and soles of the feet” -partial immunity prevents these lesions from turning into a chancre
What is seen in the CSF of patients with secondary syphilis?
-Treponemes
What kind of patient will develop early neurological symptoms of syphilis?
AIDS patient
What is latent syphilis?
-organism is in body, but not causing any signs of disease -Occurs in absence of treatment of secondary syphilis
What are the three things that can happen once syphilis becomes latent?
1/3 eradicate disease 1/3 remain with latent disease; keep reactive RPR 1/3 develop tertiary syphilis
What are the three types of tertiary syphilis?
-Benign -Cardiovascular -Neurologic
What is benign tertiary syphilis?
-Gummas: large, immunologically mediated, granulomatous lesions of skin, liver testis, hard palate ***RARE
What is cardiovascular tertiary syphilis?
-Aneurysm of ascending aorta due to invasion of vasa vasorum *RARE
What is neurologic tertiary syphilis?
Wide variety of sx’s -tabes dorsalis -strokes -dementia -paresis *CSF is usually abnormal
What is the most reliable diagnosis of primary syphilis?
-detection of treponemes in the canchre by darkfield exam *difficult in secondary lesions
What is the treatment for syphilis?
-Long acting penicillin b/c of slow dividing time
What is the Jarisch-Herxheimer reaction?
-Treatment of syphilis with penicillin is followed in 4 hours by a fever that may be high and the worsening of lesions
What organism causes Lyme disease?
-Borrelia burgdorferi
What is the natural reservoir and vector of Borrelia burgdorferi?
Reservoir: White-footed mouse Vector: hard tick (Ixodes)
What are the tree stages of Lyme disease?
1) Localized infection 2) disseminated infection 3) Persistent destructive arthritis & cardiac disease
What is stage 1 of Lyme disease?
-localized infection -nonspecific generalized symptoms -Erythema migrans
What is stage 2 of lyme disease?
-disseminated infection (multiple smaller erythema migrans) -arthritis (large joints), carditis (heart block), neurologic disease (Bell’s Palsy) “outbreak” of acute arthritis
What is stage 3 of lyme disease?
-Persistent destructive arthritis -cardiac disease
What is the cause of leptospirosis?
-Leptospira
Which species of Leptospira infects humans?
-interrogans
What is the epidemiology of Leptospira?
-Warm climates -rare in USA -infects mammals (rodents, dogs) -US soldiers in Panama *work in or around bayous, contact with sewage or farm animals, presence of rats on property
What is the clinical presentation of leptospirosis?
-Non-specific febrile illness -muscle aches -fatal jaundice -renal failure -hemorrhage
What is Weil’s disease?
-combined renal and liver failure seen in leptospirosis
What is Tabes Dorsalis?
-seen in tertiary syphilis -damage to posterior columns and dorsal roots of spinal cord -disrupts sensory perception
What is general paresis of tertiary neurologic syphilis?
-progressive disease of the nerve cells in the brain leading to mental deterioration and psychiatric symptoms
What disease is caused by Borrelia recurrentis?
-Relapsing fever
“Tick/louse bites on campers sleeping in cabins in western U.S.”
Borrelia recurrentis or Borrelia hermsii= relapsing fever
What is the reservoir and vector of Borrelia recurrentis?
Reservoir = human Vector = louse
What is the reservoir and vector of Borrelia hermsii?
Reservoir = rodents and small mammals Vector = tick (humans infected incidentally)
What is the clinical presentation of relapsing fever caused by B. recurrentis and B. hermsii?
-Fever, headache, muscle pains (nonspecific) -persists for 4-10 days, then controlled by humoral response -recurrence of symptoms keeps occuring, milder each time
Why is relapsing fever caused by B. recurrentis and B. hermsii able to relapse?
-organism changes its outer membrane proteins, escaping humoral immunity repeatedly
What kind of heart block can be caused by Borrelia burgorferi?
Atrioventricular heart block
What is the easiest way to prevent Lyme disease?
-if a tick bites you, take it off within 18-24 hours so it can’t puke on you
How are humans typically infected with Leptospira interrogans?
-swallowing water contaminated with animal urine -more common in tropical regions
