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Spirochetes - general features (microscopic, unusual features)
- microscopic: Long, slender, helically curved, gram negative bacilli (IF they gram stain)
- Axial filaments or fibrils: (flagella-like, inside) provide motility
- Outer sheath: encloses axial filaments
- insertion disks: plate-like structures that attach fibrils to the cell wall (near ends of cell)
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How are spirochetes differentiated from eachother?
- Number of axial fibrils
- Number of insertion disks
- Biochemical and metabolic features
- Morphology (somewhat)
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Treponema - pathogenic w/ disease and transmission. and nonpathogenic spp
- Pathogenic
- T. pallidum spp pallidum (syphilis) - sexual, congenital
- T. pallidum spp pertenue (yaws) - skin contact w/ infected lesion
- T. pallidum spp endemicum (endemic syphilis) - mouth to mouth
- T. carateum (pinta) - skin contact w/ infected lesion
- Nonpathogenic
- >6 sp
- Normal flora in oral cavity, genital tract
- Assocation w/ Vincent's disease?
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Treponema - general characteristics (morphology, ___phillic, habitat, culture)
- Morphology: very thin, spiral rods
- 3 periplasmic flagella at each end
- best observed with dark-field microscopy (hard to stain)
- microaerophilic
- habitat: ONLY infect humans
- culture: have only been cultured for ONE PASS (no subcultures)
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Treponema - infection method
- Enter host by penetrating intact mucous membranes or breaks in skin
- Spread to other sites via bloodstream (mechanism unclear)
- Infection of arterioles leads to inflammation, tissue destruction
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Syphillis - causative agent, transmission, disease progression IN DETAIL
- agent: Treponema pallidum pallidum
- transmission: sexual, contact w/ lesion, transplacental
- Primary syphilis: 21 days after infection
- formation of highly-infective chancre (painless ulcer filled w/ treponemes) or chancroid (painful lesion w/ tender/suppurative adenopathy)
- heals within 3-6 weeks
- no systemic signs/symptoms
- Secondary syphilis: 2-12 weeks after chancre
- systemic symptoms - fever, malaise, lymphadenopathy, sore throat, etc
- characteristic skin rash - unrestricted (palms, feet, lesions on mucous membranes) and highly infectious
- may last several weeks
- condlomata lata - mucoid fleshy wart-like growths (perianal or other moist area)
- Latent syphilis: disease subclinical but still active (serological testing)
- early latency - <1 year
- late latency - >1 year
- 1/3 patients exhibit cure (no serologic reactivity), 1/3 remain latent for life (serologic reactivity), 1/3 develop tertiary syphilis
- Tertiary syphilis: 10-25 years after initial infection
- Benign tertiary syphilis- granulomatous lesions (gummas) in skin, bone, liver
- neurosyphilis - degenerative changes in CNS
- Syphilitic cardiovascular lesions - abnormalities in aorta/aortic valves
- ocular syphilis - interstitial keratitis
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congenital syphilis - causautive agent? what is it? describe all forms of this disease
- agent: Treponema pallidum pallidum
- what: treponemes cross placenta from infected mother
- Early form: 2-10 wks post delivery
- stillbirth, prematurity, skeletal abnormalities, jaundice, rash, skin lesions, condylomata lata, CSF abnormalities
- *NOTE - untreated children develop late congenital syphilis
- Late form: 2 yrs - puberty
- asymptomatic at birth
- Hutchinson's triad - interstitial keratitis, hutchinson teeth, eighth nerve deafness
- bone deformities
- neurosyphilis
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Describe the laboratory diagnosis of Treponemes
- Direct detection: Dark-field microscopy / fluorescent Ab exam of skin lesions
- clean area, express blood, squeeze to express serous fluid, touch clean slide to fluid
- *NOTE - Observation of spiral organisms by dark-field from gential lesions is HIGHLY SPECIFIC
- PCR: not widely available
- useful for congenital syphilis
- Serodiagnosis: measure presence of Ab
- Treponemal ab - ab against ag of treponemes
- non-treponemal ab - non-specific reagin tests VDRL (Venereal disease resarch laboratory) and RPR (rapid plasma reagin)
- FTA-ABS (fluorescent trep AB absorption test) - confirmatory test following positive screening test (VDRL, RPR)
- *NOTE - not valid for therapy, will be + for life
- TP-PA (T. Palilidum Particle Aggludination) - microtiter plate, quantitative titers
- CAN be used to monitor therapy
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Treponeme treatment
- Can't be cultured therefore no susceptibility testing
- Penicillin G is drug of choice
- doxycycline if penicillin allergy (broad antibiotic)
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What are the related diseases of Syphilis w/ description?
- Yaws: primary stage lesions - elevated, granulomatous nodules
- Endemic in tropical Africa, SA, India, etc
- Endemic Syphilis AKA Bejel: Primary/secondary lesions - papules (overlooked)
- progress to gummas of skin, bones, nasopharynx
- Middle East/airid hot areas
- Pinta: scaling, painless papules, erythematous rash becomes hyperpigmented
- Tropical central and SA
- *NOTE - person-to-person transmission
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Borrelia - general information (morphology, stains, ____obic, diseases w/ spp)
- Species are morphologically similar, but have different pathogenic properties/host ranges
- morph: highly flexible spirals (3-10 loose spirals)
- actively motile: 15-20 flagella
- Stains well with Giemsa (bright field)
- Microaerophilic
- diseases
- B. recurrentis (louse) - relapsing fever
- B. duttonii (tick) - relapsing fever
- B. burgdorferi (tick) - Lyme disease
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Relapsing fever - transmission? Location? what causes it? Types? Symptoms? transmisison?
- tranmission: tick or louse bite
- found worldwide
- Endemic RF: (ticks) B. duttonii, B. hermsi, B. parkeri, B. turicatae, B. hipanica
- Epidemic RF: (louse) B. recurrentis
- Symptoms: antigenic variability causes episodic symptoms
- high temp, rigors, pains, weakness
- Febrile period 3-7 days, afebrile period days/weeks
- *NOTE - B. recurrentis pattern is shorter, but more total relapses
- transmission: ticks inject through saliva during bite
- louse is crushed and scratched into skin
- *NOTE - soft-shelled tick
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Diagnosing Relapsing fever
- Culture on Barbour-Stoenner-Kelly medium (rare)
- Stain/culture blood, biopsies, joint fluid, CSF
- Wet preps from peripheral blood of febrile patients (dark field/bright field)
- Spirochete visable w/ bright field
- *NOTE - antigenic variation make serology impractical
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Treating relapsing fever
- Spirochetes are susceptible to many Abs
- Most often treated with tetracyclines, reducing relapse rate and kill bacteria in CNS
- side effect - Jarisch-Herxheimer reactions (fever, chills, headache) caused by release of toxic subs by infecting microbes
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Lyme disease - cause? transmission?
- Borellia burgdorfei, B. garinii, afzelii, valaisana
- Transmitted via bite from Ixodes tick (attached >24 hours to transmit disease)
- *NOTE - most common vector-borne disease in NA/Europe
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Lyme disease stages
- First stage: Erythema migrans (red, target-shaped skin lesion w/ central clearing at site of the tick bite)
- also headache, fever, malaise, pain
- Second stage: weeks-to-months after infection
- neurologic disorders, carditis, arthritis
- Third stage (chronic): if infection isn't resolved by AB treatment or immune response
- characterized by chronic arthritis
- may continue for years (antigenic variation)
- spirochete persistence causes arthritis, neurological symptoms
- *NOTE - some patients develop treatment-resistant arthritic, encephalopathy, or radiculopathy
- resulting autoimmunity: molecular mimicry (B. burgdorferi causes cross-reactivity with synovial antigens, hence arthritis)
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Diagnosis of Lyme disease
- ELISA (primary screening method) or IFA & confirm with Western blot
- PCR effective early and late phase
- Organism visible in tissue sections stained with Warthin-Starry silver stain (usually too few to find this way)
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Treatment of Lyme disease
- AST is not performed (no standardized methods)
- First stage - treated w/ doxycycline, amoxicillin, cefuroxime, parenteral cephalosporins
- Late state - treated w/ broad-spectrum cephalosporins (ceftriaxone, cefotaxime)
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