Spirochetes Flashcards
What are some characteristics of the spirochetes?
Helical morphology
Flexible peptidoglycan cell wall
One of more axial fibrils which wind around the cell wall of the organism
What can Treponema and Leptospira be visualized by?
Dark Field Microscopy
What can Borrelia be visualized by?
Stained preparations
What causes syphilis?
Treponema pallidum
How is syphilis transmitted?
Sexual Contact
Via the placenta congenitally
What is the pathogenesis of syphilis?
T. pallidum will pass through mucosa/skin and multiply locally before disseminating causing symptoms to appear after they reach a critical level
What are the stages of syphilis?
Primary -Latency Secondary -Latency Tertiary
Primary Syphilis
Primary syphilis consists of an ulcerative lesion at the site of inoculation with regional adenopathy called a chancre and it is painless due to the destruction of the nerves
Secondary Syphilis
Secondary syphilis - Systemic (flu-like) illness which may develop 2-10 weeks after primary lesion heals and moist area coalesce into condylomata lata
Latent Syphilis
Defined as the presence of a positive treponemal serologic test in the absence of clinical manifestations
Tertiary (Late) Syphilis
A. Neurosyphilis
i. Asymptomatic - evidence of infection in CSF without symptoms or signs
ii. Meningovascular - chronic meningitis which can affect major arteries to brain
iii. Paresis - cortical degeneration of the brain with mental changes
iv. Tabes dorsalis - Demyelination of posterior columns and dorsal roots resulting in loss of pain, temperature and position sense in limbs with or without ataxia
B. Cardiovascular involves the proximal aorta and its branches causing
aneurysms
C. Late benign “gummatous” –granulomatous lesions in skin, mucocutaneous areas, bones
What are the signs of congenital syphilis?
Normal at birth - multiorgan involvement becomes apparent later. Rhinitis, rash, bony and cartilaginous involvement (teeth), liver, spleen, lymph nodes and CNS
How is T. pallidum visualized?
Dark Field Microscopy
Nontreponemal Reaginic Tests
Syphilis reaginic antibodies are IgG & IgM directed against cardiolipin, a lecithin-cholesterol mixture present on mitochondrial membrane - extract of beef heart
NOT Ab against T. pallidum
VDRL - Venereal Diseases Research Laboratories
Only test done on cerebrospinal fluid
RPR - Rapid Plasma Reagin
Test done on the serum
Specific Treponemal Tests
Measure specific antibody against T. pallidum
FTA-Abs - Fluorescent Treponemal Antibody - Absorption Test
Serum is absorbed with extracts of cultivated non-T. pallidum treponeme. Antigen is killed Reiter strain of T. pallidum on a slide.
MHA-TP - Microhemagglutination Treponemal pallidum also known as TPPA (particle agglutination)
Treponemal antigens adsorbed onto erythrocytes or
latex particles. Agglutinated by serum containing antibody against T. pallidum.
EIA/CIA
These are automated, inexpensive tests that are now done in large laboratories and and used to screen. A positive EIA should be confirmed with a quantitative Nontreponemal test.
What is the traditional approach to syphilis diagnosis?
One of the specific tests should be used to confirm a positive reaginic test result.
VDRL/RDR -> EIA
What is the new method to syphilis diagnosis?
Now “reverse algorithm” in which positive treponemal test is confirmed with a nontreponemal test when EIA is used for screening.
EIA -> VDRL/RDR
What is the treatment for syphilis?
Long acting injectable formulation because of very long generation time. Therefore Benzathine Penicillin G.
What is the treatment for late syphilis?
Must use intravenous Penicillin treatment for late syphilis.
Jarisch Herxheimer Reaction
Fever, chills, headache, and hypotension after treatment due to the release of toxins from killed spirochetes.
How are Borrelia visualized?
Stain under light microscope
What does Borrelia recurrentis cause?
Relapsing Fever
What is unique about B. recurrentis that leads to its specific effects?
It can gene switch on a linear plasmid from silent locus to
active expression locus repeatedly, which auctions to evade the immune system and lead to the relapsing phenomena of its illness.
When is relapsing fever often found?
As it is louse-borne, in times of war and famine.
What is the reservoir of B. recurrentis?
None. It is transferred human to human via the louse
What can happen during treatment of relapsing fever with antibiotics?
Jarisch-Herxheimer reactions
What does Borrelia burgdoferi cause?
Lyme Disease
What is the reservoir of B. burgdoferi?
Deer and white-footed mouse
What is the vector of B. burgdoferi?
Ixodes ticks
What form of the Ixodes ticks is primarily responsible for human infection?
Nymph
What is the pathogenesis of Lyme disease?
Tick bite leads to local multiplication and entrance into blood and lymph
What are the early manifestations of Lyme disease?
Erythema migrans (EM). Expanding erythematous skin lesion at site of tick bite
What are the late signs of Lyme disease?
Arthritis
Encephalopathy
Chronic skin lesions - Acrodermatitis
How is leptospira acquired in humans?
Humans acquire the organism by contact with infected animal urine usually through contaminated water
What are the hosts of leptospira?
Zoonosis with many animal hosts: Rats, mice, wild rodents, dogs, swine, cattle
What is the first stage of leptospirosis?
First stage (Bacteremia): fever, headache, muscle ache, abdominal pain, conjunctival suffusion
What is the second stage of leptospirosis?
Second stage (Detectable antibody): aseptic meningitis or generalized illness with myalgias, headache, rash, uveitis
What happens in a case of severe leptospirosis?
The stages blend in severe disease with prominent hepatitis, kidney involvement, and hemorrhage.
Mortality in severe disease 5-10%
The test used to follow patients to ensure adequacy of treatment for syphilis is?
A. RPR B. MHA-TP C. FTA-ABS D. CBC and differential E. Darkfield of urine
A. RPR
