CLS04 - Spirochetes

  1. 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)
  2. How are spirochetes differentiated from eachother?
    • Number of axial fibrils
    • Number of insertion disks
    • Biochemical and metabolic features
    • Morphology (somewhat)
  3. 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?
  4. 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)
  5. 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
  6. 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
  7. 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
  8. 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
  9. Treponeme treatment
    • Can't be cultured therefore no susceptibility testing
    • Penicillin G is drug of choice
    • doxycycline if penicillin allergy (broad antibiotic)
  10. 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
  11. 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
  12. 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
  13. 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
  14. 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
  15. 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
  16. Lyme disease stages
    • First stageErythema 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 autoimmunitymolecular mimicry (B. burgdorferi causes cross-reactivity with synovial antigens, hence arthritis)
  17. 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)
  18. 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)
Card Set
CLS04 - Spirochetes
CLS04 - Spirochetes