Spirochetes Flashcards
spirochetes morphology
organisms are elongated, flexible, helicoid
gram negative
3 types of spirochetes that cause human disease
treponema- syphilis, yaws, pinta
borrelia- cause of relapsing fever and lyme disease
leptospira- leptospirosis
treponema pallidum general characteristics
causes syphilis
too small to be seen w/ gram stain microscopy- must use darkfield microscopy, immunofluorescece, or electron microscopy
cannot be grown on culture
killed easily by heat, drying, soap or water
treponema pallidum transmission
passed via direct contract of genitalia or mucous membrane
not transmissable during late disease
transmitted mother to featus- causes still birth, abortion, etc
transmitted by transfusion
treponema pallidum pathogenesis
primary lesion- occurs on genitalia 1-4 weeks after infection- chancre- spontaneously heals
secondary lession- organism has disseminated- generalized skin rash or mucosal lesions after primary lesion
tertiary lesion- many years after infection, occurs in the CNS, aortic valve
treponema pallidum incubation period
2-6 weeks
treponema pallidum diagnosis
lesions
history of exposure
demonstration of organisms in lesoins
serologic tests- early- wassermann Ab,
non specific tests: VDRL, flocculation test
specific tests: FTA-ABS- pt serum is first absorbed w/ non pathogenic treponemes to remove non specific Abs, then added to T-pallidum and visualized by fluorescent Ab
microhemagglutination tests- involving RBCs coated with T pallidum Ag and pts serum
ELISA
TPI- Ab from pt rxn w/ living T pallidum
false positive and negatives w/ syphilis
false positive- in presence of malaria
highest risk group for syphilis
male on male
syphilis treatment
pencillin
vaccines to syphilis
none
other treponemal disease
Yaws- tropical disease caused by t pertenue. transmission thru skin lesions. primary lesion resembles raspberry
bejel- found in children in syria. similar to yaws, treated w/ penicillin
pinta- central and south america. caused by T carateum. flat, nonulcerating skin lesions of hands, feet, and scalp that heal but leave depigmentation. penicillin
borrelia general characteristics
cause relapsing fever. visible by microscopy. cannot grown on artifical media
borrelia recurrentis
human to human via body louse
3-10 episodes of fever/recovery d/t Ag variation on linear plasmid
diagnosis- wrights stain or dark field microscopy
treatment- tetracycline
commonly found in rustic, rodent infected cabins (tick born) or war areas (louse born)
borrelia burgdorferi transmission
lyme disease
tick transmission- white footed mouse resevoir, deer tick transmit
