Spirochetes 9/8/15 Flashcards
Describe the structural characteristics of Treponema pallidum.
Spiral bacterium
outer membrane with 3 axial fibrils = motility
flexible peptidoglycan cell wall
No LPS
REALLY thin = seen only by darkfield microscopy
List some cultural characteristics of T. pallidum.
- Generation time = 30 hours
- Doesn’t grow well on artificial media
- Microaerophilic (3-5% O2)
- Very sensitive to drying/heat
Describe the transmission of T. pallidum.
Intimate sexual contact with infective primary/secondary lesions
Passes thru placenta = congenital infection
Describe primary syphilis infection.
- ulcerative lesion at site of inoculation
- regional lymphadenopathy
- painless papule = chancre
- heals spontaneously
-no systemic manifestations
Describe secondary syphilis infection.
- systemic signs and symptoms
- flu-like illness (2-10 wks after primary lesion heals)
- Papulosquamous rash (entire body)
- Condylomata lata: papules coalesce in moist areas
- Generalized lymphadenopathy
- Heals spontaneously but may recur over four years
Describe latent syphilis.
- Positive treponemal serologic test
- No clinical manifestations
- Untreated person
What effects are seen in late (tertiary) syphilis infection.
- Neurosyphilis: CNS affected
- Cardiovascular syphilis: proximal aorta affected (AAA could result)
- Benign Gummatous syphilis: tumor-like lesions in bone/cartilage
Describe congenital syphilis infection effects.
- Multi-system disease:
- Rhinitis: purulent discharge = snuffles
- Rash
- Bone/cartilage/teeth involved
- hepatomegaly/spleen enlargement
- Lymph nodes/CNS affected
Describe changes seen in Neurosyphilis.
- Asymptomatic
- Meningovascular: chronic meningitis affecting arteries and cranial nerves
- Paresis: dementia from cortical degeneration
- Tabes dorsalis: demyelination causing loss of pain and temperature sensation
What 2 microscopic techniques are used to diagnose syphilis?
- Darkfield: primary/secondary lesions
- Direct Fluorescence Antibody Test: monoclonal Abs, material from lesion/biopsy
What are some of the non-treponemal tests for syphilis serology, and how do they work?
- Both use antibodies that are NOT directed agains T. pallidum specifically
- RPR: Rapid Plasma Reagin = in serum
- VDRL: Venereal Disease Research Labs = done on CSF
- False positive tests common
What are some Treponemal Serology tests and how do they work?
-Measure specific antibody against T. pallidum
- FTA-Abs: Fluorescent Treponemal Antibody-Absorption Test (either reactive or non-reactive)
- TPPA - PA: Particle agglutination
- EIA/CIA (ELISA): Chemiluminescence immunoassay (high false positive rate)
- Decrease false positives when confirming RPR assay
THINK: all of these end in “a” = Antibody Against T pallidum
What are the differences between the traditional and the reverse diagnostic algorithms of Syphilis?
Traditional: Non-specific to specific test
Reverse: Specific to non-specific to Specific
What are treatment options for Syphilis?
–Benzathine Penicillin G (IM) = single dose
Alternate = Tetracycline
–Jarisch-Herxheimer reaction (after treatment)
- fevers, chills, headache, hypotension
- Release of toxic products from killed Spirochetes
List general characteristics of Borrelia.
- Larger Spirochetes
- Mammalian reservoir (spread to humans via tick/louse vectors)
- Results in Relapsing Fever or Lyme Borreliosis
Describe culture characteristics of B. recurrentis.
B. recurrentis: Wright’s Stained Blood Smear: Blood, serum or tissue-containing media
Describe antigen diversity in B. recurrentis.
Alter antigenic structure during infection
Gene switch from silent to expressed locus (like. N. gonorrheae) on plasmid
Relapse caused by emergence and multiplication of antigenic variants
Describe the differences in epidemic and endemic relapsing fever.
Epidemic: Louse-borne (no reservoir)
-Times of war and famine (“lousy conditions”)
Endemic: Tick-borne (rodent reservoir)
-Mountain regions of Western US
What are the clinical manifestations of Relapsing Fever?
Fever
Chills
Mm pain
Headache
RELAPSES (antigenic variation)
How is Relapsing fever diagnosed?
Blood smear
Serology: cross reactions with other Spirochetes
What treatment options are available for Relapsing Fever (B. recurrentis)?
-tetracycline, erythromycin
- Jarisch-Herxheimer reactions common (like Syphilis)
- fevers, chills, headache, hypotension
Describe Lyme Borreliosis.
Systemic spirochetal disease resembling syphilis in its stages and prominent involvement of skin and CNS
What are the primary reservoirs of Borrelia burgdorferi?
Deer and white-footed mouse
What is the major vector for Lyme Borreliosis?
Tick : Ixodes
Describe early stage Lyme Disease.
- Erythema migrans = expanding erythematous lesion at site of tick bite
- Flu-like illness
Describe Early Disseminated Lyme Disease.
- Fatigue
- Headache
- Fever
- Malaise
- Heart block
- CNS (CN VII): facial nerve paralysis
- Arthritis
What stage of Lyme Disease is associated with the following symptoms?
- Arthritis: recurrent, esp knees (with fluid)
- Encephalopathy: fatigue, memory loss, cog defects
- Chronic skin condition: acrodermatitis chronica atrophicans
Late stage
How is Borrelia burgdorferi diagnosed?
Serology: ELISA or IFA
-confirm with Western Blot
PCR: skin, synovial fluid, CSF
What treatment options are available for Lyme Borreliosis?
- Early: Amoxicillin, doxycycline (oral)
- Late: Pen G or ceftriaxone (parenteral)
What prevention methods are used against Lyme Borreliosis?
- Repellants
- Tick checks/removal (have to be attached for 24 hours before infection transmitted)
What is the epidemiology of Leptospirosis?
- Zoonosis with many animal hosts
- rodents, dogs, cattle, swine
- Transmission = ingestion/direct contact with food or water contaminated with infected animal urine
Describe the first stage of Leptospirosis.
- Bacteremia (present in blood): first week
- fever
- headache
- myalgia
- conjunctival suffusion (redness)
- ab pain
- vomiting
Describe the second stage of Leptospirosis.
- Immune: present only in urine: first month
- aseptic meningitis
- generalized illness
- uveitis (inflammation in eye)
- rash
- fever
What symptoms are associated with the severe stage of Leptospirosis?
-First 2 stages blended: in blood and urine
-prominent hepatitis/jaundice, kidney involvement, hemorrhage
- low mortality
- about day 3 onward
How are infections cause by Leptospirosis interrogans diagnosed?
Culture: blood and CSF (early), urine (late)
Serology: MAT = microscopic agglutination test after first week
What are treatment options for Leptospirosis?
-penicillin, ceftriaxone, doxycycline
