WEEK 17: SPIROCHETES Flashcards
- Helical-shaped, motile, unicellular bacteria
- 0.1- to 3.0-μm wide by 5- to 20-μm long
- Exhibit various types of motion in liquid media
- Free-living or survive in association with animal or human hosts
Spirochetes
Syphilis
Treponema pallidum subsp. pallidum
- Relapsing fever
- Lyme disease
Borrelia
Leptospirosis
Leptospira
Rat-bite fever
Spirillum minor
- Obligate aerobic helical rods 0.1-μm by 5- to 15-μm long that are tightly coiled, thin, and flexible.
- Leptospirosis: L. interrogans
- 20 serovars
- Most common
- Icterohaemorrhagiae, Australis, and Canicola
Virulence factors:
* Unknown but may include
* Reduced phagocytosis
* Soluble hemolysin
* Endotoxin
Leptospires
- Organisms in mud or water enter through breaks in the skin or intact mucosa.
Symptoms:
* Initial phase
* Fever, headache, malaise, and severe myalgia
* Conjunctival suffusion seen in less than half
* Can involve hepatic, renal, and central nervous systems
* Renal lesions are interstitial nephritis with glomerular swelling and hyperplasia.
* Illness lasts from less than 1 week to 3 weeks.
Leptospires
- Late manifestations caused by host immunologic response to infection.
- Weil’s disease: severe systemic disease
- Jaundice, acute renal failure, hepatic failure, intravascular disease
- Can be fatal
Leptospires
Organism that causes Weil’s disease.
Leptospires
This organism is susceptible to:
- Streptomycin
- Tetracycline
- Doxycycline
- Penicillin
- Some limited effectiveness if used early (before fourth day of illness)
Leptospires
- Helical bacteria 0.2 to 0.5 μm by 3 to 20 μm in length
- Spirals vary between 3 to 10 per organism
- Less tightly coiled than leptospires
Borrelia spp.
- Pediculus humanus louse-borne infection
- Epidemic relapsing fever
- Transmission by crushing or scratching lice into skin
B. recurrentis and B. duttonii
- Tick-borne infection: Ornithodoros ticks
- Endemic relapsing fever
- Transmitted by saliva during bite
B. hermsii (borreliae)
Symptoms:
- Incubation period is 2 to 15 days.
- High fever (104°F) with shaking chills
- Periods of 3 to 7 days
- Delirium
- Severe muscle aches and pain in bones and joints
- Followed by remission and subsequent repeat of symptoms
- Sometimes hepatosplenomegaly and jaundice
- Neurologic symptoms
- Lymphocytic meningitis and facial palsy
- Rarely fatal
Relapsing Fever
Drug of choice for relapsing fever.
Tetracyclines
- Lyme disease
- First described in Lyme, Connecticut
- North America and Europe
B. burgdorferi
“bulls-eye rash”
B. burgdorferi Clinical Manifestations (stage 1)
Antibiotics used for B. burgdorferi infections (early stage)
doxycycline
Syphilis
Treponema pallidum subsp. pallidum
Yaws
Treponema pallidum subsp. pertenue
Endemic syphilis
Treponema pallidum subsp. endemicum
Pinta
Treponema pallidum subsp. carateum
Transmission:
- Infection caused by sexual contact (mucous membranes)
- Can enter via cuts, abrasions, or directly through intact mucous membranes
- Can enter other sites such as the lip or transplacental
Incubation period:
* Disseminate throughout the body
* 10 to 90 days (usually about 3 weeks)
Syphilitic Infection
- Chancre at infection site (usually one but sometimes several in human
immunodeficiency virus (HIV)–positive patients) - Clean, smooth base, edge slightly raised and firm
- Painless but may be tender
- Heals in 3 to 6 weeks
- Base contains spirochetes that can be identified by dark field microscopy or
immunofluorescence or serology
Primary syphilis
