BACT 211: Spirochetes, Special, & No Cell Wall

Spirochetes

• Microscopy:

  • Gram (-) bacilli

  • Long, slender, helical, & curved

  • Has fibrils/axial filaments

Borrelia spp

• Microscopy:

  • B. burgdorferi (visualized using Warthin-Starry silver stain)

  • Thicker, looser coils

• Transmission:

  • Ixodes tick bite

• Manifestation:

  • Tickborne & Louseborne relapsing fever

  • Lyme disease

Treponema pallidum subsp. pallidum

Causes “Venereal syphilis” (great pox / evil pox)

Treponema pallidum subsp. pertenue

Causes “Yaws”, found in tropics

Treponema pallidum subsp. endemicum

Causes “Bejel”, found in desert region

Endemic Syphilis

Other name for Bejel

Treponema pallidum subsp. carateum

Causes “Pinta”, found in Central & South Africa

Primary Syphilis

• Manifestation: Hard chancre

• Dark Field Microscope: (+)

• Serological Test: (-)

Secondary Syphilis

• Manifestation: Condylomata lata

• Dark Field Microscope: (+)

• Serological Test: (+)

Latent Syphilis

• Manifestation: none (migrated to brain)

• Dark Field Microscope: (-)

• Serological Test: (+)

Tertiary Syphilis

• Manifestation: Gumma, Neurosyphilis, Cardiovascular disease (CVD)

• Dark Field Microscope: (-)

• Serological Test: (+)

Treponema spp

• Poorly stained by Gram stain

• Best observed in dark field & phase contrast microscope

• Few proteins on cell surface

  • hard to kill by immune system

• Rapidly destroyed by environment

Erythema Migrans

Red spots that travel to different parts of the body; early signs of lyme disease

Leptospira spp

• Spx Collection:

  • Blood & CSF: first 10 days of illness

  • Urine: 2nd week - 30 days after onset

• Manifestation:

  • Leptospirosis (2-20 days after exposure)

Doxycycline

Prophylaxis taken to ensure prevention of acquiring leptospirosis after walking in a flood

Rickettsia spp

• Simplest bacterial form

  • Transitional organism between bacteria & virus

• Microscopy:

  • Gram (-) pleomorphic

  • Motile

• Fastidious

• Obligate intracellular parasites

  • won’t grow in cell-free media

• Transmission:

Spotted Fever Group

• Ticks

• Rocky Mountain Spotted Fever

  • most serious

  • Rashes: extremities to trunk

• Boutonneuse Fever

  • Tache noires (black spot)

• Ricketssialpox

Typhus Group

• Lice

  • Rashes: trunk to extremities

Rickettsia rickettsii

• SFG

• Western hemisphere

  • Rocky Mountain spotted fever (tick bite)

Rickettsia japonica

• SFG

• Japan

  • Japanese spotted fever (tick bite)

Rickettsia felis

• SFG

• USA, Europe, & Africa

  • Flea-borne spotted fever

Rickettsia akari

• SFG

• USA, Ukraine, Croatia, & Korea

  • Rickettsialpox (mite bite)

Rickettsia typhi

• TG

• Worldwide

  • Endemic (flea feces)

Rickettsia prowazekii

• TG

• Worldwide

  • Epidemic (Louse feces)

  • Recrudescent (yrs after epidemic typhus)

Serodiagnosis

Method of choice for detection of Reckettsia

Weil-Felix

Based on the cross reactivity of the patient’s Ab w/ polysaccharide Ag of OX-19, OX-2 (P. vulgaris strain), & OX-K (P. mirabilis)

Chlamydia spp

• Can’t synth own ATP

• “Energy parasites”

• Obligate intracellular organism

• Fastidious (require living cells for growth)

• Microscopy:

  • Gram (-) small

  • Non-motile

Reticulate Body

• Intracellular & metabolically active form of Chlamydia

• Replicative & non-infectious

• Binary fission

Elementary Body

• Extracellular form of Chlamydia

• Infectious

• Spherical in shape

  • resembles Gram (-) bacilli w/ rigid cell wall

• Infects thru inducing active phagocytosis

Chlamydia trachomatis

• Major sexually transmitted pathogen

• Specimen: cell scrapings

• Manifestation:

  • Pelvic inflammatory disease

  • Ocular trachoma

  • Lymphogranuloma venereum