CH 23: Spirochetes

General characteristics

• slender, flexible, helical/spiral

• flexible cell wall w/ outer sheath membrane for motility

  • difficult to stain

• two major families

  • Leptospiracaea

    • Leptospirosis spp.

  • Spirochaetaceae

    • Borrelia spp.

    • Treponema spp.

Leptospirosis interrogans

• causes Leptospirosis

  • zoonotic infx

• morphology/testing

  • tightly coiled helical organisms w/ hooked ends

  • no visibility on brightfield

    • visibility on dark field and fluorescent microscopy

  • detect in blood at 1 wk, urine at 1-3 wks of infx

  • culture: Fletcher’s or Stuart medium at room temp

  • antibody testing most common

Leptospirosis

• zoonotic infx

  • rats, skunks, dogs, cattle

  • contaminated urine in water sources

• liver, kidney, and CNS involvement

• Weil’s Dx - severe systemic infx lead to kidney/organ failure

Borreliae

• long, thin, flexible spirochetes

• relapsing fevers and generally arthropod borne

• morphology/testing

  • Kelly medium growth (uncommon)

  • microscopy (bright and dark)

  • immunological testing

Borrelia recurrentis

• relapsing fever

  • wax and wane in cycles for weeks to months

• arthropod borne

  • ticks or human body lice

• only spirochetal illness where viewed in blood w/ brightfield microscopy

• testing difficult

Borrelia burgdorferi

• causes Lyme dx

  • most common tick borne illness in US

• dx occurs in 3 stages

  • 1. localized: Bull’s eye rash (60%)

  • 2. early disseminated: bacteria enters blood

    • flu-like symptoms, bone/joint pain, fatigue, ps heart/CNS symp.

  • 3. late stage: chronic symptoms last for years

    • arthritis or heart issues

Treponema

• thin, spiral organisms

• viewed best dark-field microscopy

• testing done serologically

Treponema pallidum subsp. pallidum

• causes syphilis

  • transmitted thru direct contact w/ infected mucous membrane

    • sexual contact or vaginal childbirth

  • ability to cross intact mucous membrane and placenta

• 4 stages

  • primary

  • secondary

  • latent

  • tertiary

Primary and secondary syphilis

• primary (1-3 wks after infx)

  • development of chancre site of infx

  • usually single lesion

  • highly contagious, but not non-tender

  • testing

    • direct microscopy from chancre

    • serology testing will be (+) 1-4 wks after chancre development

• secondary (2-12 wks after lesion)

  • systemic dx: fever, sore throat, swollen lymph nodes, and macular rash

  • all lesions contagious

  • direct and serology testing usually (+)

Latent and tertiary syphilis

• latent

  • bacteria are dormant and clinical manifestations are absent

  • NOT contagious

  • direct testing (=), serology tests taper off and become (=) too

• tertiary (decades later)

  • 25-40% of untreated syphilis

  • granulomatous lesions on skin and bones

    • degenerative neurosyphilis, arthritis, cardiac involvement

  • NOT contagious

  • serology tests (+)

Congenital syphilis

• transmitted to fetus by bacteria crossing placenta

• affect many body systems severely

  • deforming or life-threatening

• affects bones, brain, and heart

Syphilis testing

• serological testing - antibodies in serum of pt

• nontreponemal testing - screening

  • generic antibodies

  • VDRL and RPR

• treponemal testing - confirmatory test

  • specific antibodies

  • FTA-ABS and TP-PA

  • (+) longer after tx/latency

Other treponemal dx

• T. pallidum sbsp. pertenue

  • Yaws - non venereal dx similar to syphilis

• T. pallidum sbsp. endemicum

  • Bejel - endemic syphilis

• Treponema carateum

  • Pinta - nonverenal skin dx