Spirochetes-Treponemes Flashcards
What features do the Spirochetes share in common?
Flexible, spiral peptidoglycan cell well
One or more axial fibrils (“internal flagellum”) that assists in maintaining coiled shape
Three major genera of Spirochetes responsible for human disease:
Treponema, Borrelia, Leptospira
Structural characteristics of Treponema pallidum
Outer membrane does not contain lipopolysaccharide
Thin, tightly coiled
How is Treponema pallidum visualized?
Must use Darkfield microscopy or immunofluorescence for visualization
Describe Treponema pallidum culture and growth.
Can only be cultured few generations on media with rabbit epithelial cells
Very sensitive to drying and heat
Microaerophilic (only 3-5% oxygen)
___________________ is the 3rd most common sexually transmitted infection in U.S.
Treponema pallidum (syphilis) is the 3rd most common sexually transmitted infection in U.S.
Incidence of syphilis is particularly rising among what demographic?
MSM
Treponema pallidum is found only in ____.
humans
How is syphilis transmitted?
via direct sexual contact with an infective primary or secondary mucosal lesion on the genitals, anus, or lips.
When and how does congenital infection with syphilis occur?
Congenital infection occurs in utero
by transmission across the placenta
Clinical hallmarks of primary stage syphilis:
Painless ulcer (chancre) at the site of inoculation
Painless inguinal lymphadenopathy
No systemic manifestations (no fever, rash, or fatigue)
Darkfield positive - teeming with spirochetes
Clinical hallmarks of secondary stage syphilis:
Flu-like syndrome
Fever and diffuse lymphadenopathy
Generalized mucocutaneous rash (involves the palms/soles)
Condylomata lata (papules coalesce into large lesions)
Clinical hallmarks of latent stage syphilis:
Asymptomatic
Clinical hallmarks of tertiary stage syphilis:
Granulomatous lesions of skin/organs/bone (gummas)
Neurosyphilis
Cardiovascular syphilis
Timeframe of primary stage syphilis:
10-90 days after infection
Timeframe of secondary stage syphilis:
2-10 weeks after chancre
Peaks 3-4 months after infection
Timeframe of latent stage syphilis:
A few years to as many as 25 years
Progresses to tertiary syphilis if untreated
Timeframe of tertiary stage syphilis:
Generally at least 5-10 years since infection
Describe the syphilis chancre:
smooth margins and crusted base
Describe Cardiovascular Syphilis:
Cardiovascular Syphilis – chronic large vessel vasculitis that involves the wall of the aorta, causing aortic aneurysms/dissection
Name the stage of Neurosyphilis:
CSF inflammatory changes: pleocytosis and elevated protein
Early (Secondary) - Asymptomatic
Name the stage of Neurosyphilis:
No symptoms
Early (Secondary) - Asymptomatic
Name the stage of Neurosyphilis:
Meningitis and Vasculitis
Early (Secondary) - Symptomatic Meningovascular
Name the stage of Neurosyphilis:
Headache, neck stiffness, fever, cranial neuropathy, stroke
Early (Secondary) - Symptomatic Meningovascular
Name the stage of Neurosyphilis:
Dementia, aphasia, muscle weakness, hallucinations
Late (Tertiary) - General paresis
Name the stage of Neurosyphilis:
Chronic meningoencephalitis leading to brain atrophy
Late (Tertiary) - General paresis
Name the stage of Neurosyphilis:
Infection/inflammation of the spinal cord
Demyelination of spinal cord posterior columns and dorsal roots
Late (Tertiary) - Tabes dorsalis
Name the stage of Neurosyphilis:
Imbalance and Ataxia
Loss of pain and temperature sensation
Late (Tertiary) - Tabes dorsalis
Symptoms of congenital syphilis:
Rhinitis (‘snuffles’ - heavy nasal discharge)
Widespread rash, hepatomegaly
Long-term effects of congenital syphilis:
Bone and teeth malformation – frontal ‘bossing’
Facial abnormalities – ‘saddle nose’
Blindness, deafness, cardiovascular disease
Methods of non-serological diagnosis of Treponema pallidum:
Darkfield microscopy
Direct fluorescent antibody
PCR
Unique qualities of non-treponemal tests:
Measures reaginic (lipid) antibodies - NOT directed specifically against T. pallidum
Patients revert to negative results with treatment or enough time
Can be used to follow treatment
Unique qualities of treponemal tests:
Tests remain positive for life, regardless of treatment
Cannot be used to monitor response to treatment
3 types of serologic specific treponemal tests:
Fluorescent treponemal antibody absorption Tests (FTAAbs)
T. pallidum particle agglutination (TP-PA or TP-HA)
T. pallidum enzyme immunoassay (EIA) or chemiluminescence immunoassay (CIA)
2 types of serologic non-treponemal tests:
VDRL (serum & CSF) – Venereal Disease Research Laboratory
RPR (serum) – Rapid Plasma Reagin
True or False: A positive non-treponemal test is always confirmed with a specific treponemal test
True
When are non-treponemal tests likely to be negative?
Early primary stage, late-latent and tertiary syphilis, following treatment, or after many years
What is unique about a reverse sequence diagnostic algorithm for syphilis?
Begins with a specific treponemal test (EIA or CIA)
Best treatment of treponema pallidum? Alternatives?
IM injection of Benzathine penicillin G (long acting)
Doxycycline is an alternative, but is not as effective
Treatment for neurosyphilis:
IV penicillin G
What is the Jarisch-Herxheimer reaction?
Reaction related to the release of toxic products from dying spirochetes due to Abx.
When are both non-treponemal and treponemal tests likely to be positive?
Secondary stage
Describe transmission of Borrelia.
Larger spirochete that is spread from a mammalian reservoir to humans by tick or louse vectors
Name the 2 clinical infections caused by Borrelia species.
Causes Relapsing fever and Lyme borreliosis (Lyme disease)
Is Borrelia gram-positive or gram-negative?
Neither
How are Borrelia species visualized?
Stain with Giemsa or Wright’s stain
Why is little know about pathogenesis of diseases caused by spirochetes?
They are very difficult to culture due to complex nutritional needs.
How does B. recurrentis escapes immune recognition?
By altering antigenic structure during infection:
Gene switch from silent to expression locus on plasmid
Relapses are caused by emergence and multiplication of antigenic variants
2 most common geographic areas for Borrelia burgdorferi cases :
Northeast and Mid-Atlantic states (Maine to Virginia)
Upper Midwest (Minnesota and WI)
Primary Animal reservoirs of Borrelia burgdorferi:
White-tailed deer and white-footed mouse
Name the hard tick that transmits Borrelia burgdorferi in the NE and Midwestern U.S.
Ixodes scapularis
Name the hard tick that transmits Borrelia burgdorferi in the Western U.S.
Ixodes pacificus
Most lyme disease is transmitted by the bite of a ________.
Most lyme disease is transmitted by the bite of a nymph
Risk of human infection by Lyme disease is greatest in _________ and __________.
Risk of human infection is greatest in late spring and early summer
Clinical Manifestations of Early Stage (3-30 days post bite) Lyme Disease:
Erythema migrans: expanding erythematous target-shaped lesion at site of tick bite
Flu-like illness: fever, chills, malaise, myalgias
Clinical Manifestations of Early Disseminated (weeks days post bite) Lyme Disease:
Arthritis and arthralgia
Cardiac dysfunction (conduction block)
Facial nerve paralysis or other cranial neuropathies
Clinical Manifestations of late-stage Lyme Disease:
Recurrent/relapsing arthritis in large joints
Acrodermatitis chronica atrophicans -hyperpigmented rash on the dorsal surface of the hands
Describe the two-tiered testing system for Lyme disease:
Initial screening immunofluorescence assay (EIA, ELISA, IFA) - must allow time for Abx to be present
Confirmed with a second, more specific Western Blot test - Detects specific IgG and IgM antibodies against Borrelia burgdorferi
What evidence would suggest the Borrelia burgdorferi infection of the CNS?
Elevated lymphocytic pleocytosis and elevated protein in CSF
Specific serology testing (IgG and IgM) from CSF
PCR from CSF (reference laboratory)
