chapter 24 chapter 24 spirochetes spirochetes chapter 24 chapter 24 spirochetes spirochetes

 thin-walled, flexible, spiral rods  motile through the undulation of axial filaments

Cause disease in human  Treponema :  Leptospira :  Borrelia:

Histology: Treponema pallidum Histology: Treponema pallidum - testis infected rabbit

Treponema pallidum transmission – genital – placenta  x 6-15um; 8-14 small, regular spirals syphilis syphilis

characteristics  spirochetes  not seen on Gram-stained smear  seen only by darkfield microscopy, silver impregnation or immunofluorescence  not cultured in vitro

habitat and transmission habitat: the human skin or mucous membranes intimate contact intimate contacttransmission from mother to fetus from mother to fetus across the placenta across the placenta

Pathogenesis  Produce no important toxins or emzymes  multiplies at site of inoculation  spread widely via the blood stream

Early syphilis  Primary syphilis: 2-10 weeks, local, nontender ulcer (chancre)  Secondary lesions: maculopapular rash or moist papules rich in spirochetes and highly infectious rich in spirochetes and highly infectious 1st & 2nd lesions heal spontaneously 1st & 2nd lesions heal spontaneously some remain latent

I II III

Tertiary syphilis (late phase)  Gummas 树胶肿, aortitis 主动脉炎, central nervous system involvement, cardiovascular lesions  Treponemas are rarely seen, noninfectious

Congenitial syphilis Infected woman fetus Stillbirth Multiple fetal abnormalities

Treatment Penicillin is effective in the treatment of Penicillin is effective in the treatment of all stages

Leptospira interrogans Disease leptospirosis leptospirosis

Leptospira

characteristics characteristics  tightly coiled, fine spirochete  Not stained, can be seen on dark-field microscopy  Grow in bacteriologic media containing serum (Korthoff media)

Habitat and transmission habitat: rats, domestic livestock habitat: rats, domestic livestock transmission: via animal urine---- contaminate water and soil transmission: via animal urine---- contaminate water and soil (human contact contaminated environment) (human contact contaminated environment)

pathogenesis  High risk population: peasant, person who fight a flood, or fishing  Ingested or pass through mucous membranes or skin  Circulate in the blood  Multiply in various organs

Clinical findings  Initial bacteremic phase: fever, chills and intense headache (conjunctivae congestion, pain of gastrocnemius, (conjunctivae congestion, pain of gastrocnemius, lymphadenectasis) lymphadenectasis)  Subsequent immunopathologic phase: meningitis (stiff neck), liver damage (jaundice) and impaired kidney function

diagnosis  History of possible exposure  Suggestive clinical signs  Detect Ab  Isolation of leptospiras

Treatment Penicillin G

 avoid contact with the contaminated environment  vaccination of livestock and pets  rat control prevention