spirochetes Flashcards
- Define the major characteristics of spirochetes? How are they different from other bacteria?
Gram negative corkscrew shaped bacilli. Do NOT have endotoxin (LPS). • They have endoflagella (axial filaments) in their periplasmic space. The endoflagella begin at each end of the organism and wind around it, extending to and overlapping at the midpoint.
List the types of spirochetes
From the family treponemataceae: Treponema, Borrelia, and Leptospira.
Treponema growth characteristics
Treponema reproduce by transverse fission. • Pathogenic Treponema pallidum (e.g. those that cause syphilis) cannot be cultured continuously on artificial media, in embryonated eggs or in tissue culture. T. pallidum will remain motile for 3-6 days at 25°C in 1-4% oxygen in a special broth medium.
Leptospira growth characteristics
Grows aerobically at 28-30C. Uses long chain fatty acids as energy source and urea as nitrogen source
List the diseases caused by treponema
T. pallidum subsp pallidum: causes syphilis. T. pallidum subsp pertenue: causes yaws. T. pallidum subsp endemicum: causes endemic syphilis or bejel. T. carateum: causes pinta
Pathogenesis of syphilis
3 week incubation period > primary syphilis (2-6 weeks) > asymptomatic period (2-24 weeks) > secondary syphilis (2-6 weeks) > latent syphilis > asymptomatic period (3-30yrs) > tertiary syphilis
During which stages of syphilis is the infection transmissble
primary and secondary syphilis are transmissible by blood products and lesions are highly infectious. During latent and tertiary syphilis infection is NOT transmissible by blood and lesions are caused by immune mediated destruction of tissues
What percent of pts with syphilis will develop tertiary syphilis and how many of those will die?
30% of untreated patients develop tertiary syphilis and 25% die of this disease
Which Sx of syphilis are due to cell mediated hypersensitivity vs invasion
invasion: neurosyphilis, Tabes, and cardiovascular. Cell mediated: gummas in skin bones and liver and cardiovascular syphilis
describe primary syphilis
characterized by one or more chancres (ulcers) which may be located anywere on the body, even oral cavity. Regional lyphadenopathy (painless) • Demonstration of T. pallidum in clinical specimens by darkfield microscopy, direct fluorescence antibody (DFA-TP), or equivalent methods. serologic tests may not be positive during early primary syphilis
describe development of a chancre
Progresses from macule to papule to ulcer. Typically painless, indurated, and has a clean base. Highly infectious. Heals spontaneously within 3-6 weeks
describe secondary syphilis
localized or diffuse mucocutaneous lesions, generalized lymphadenopathy, malaise, alopecia,condylomata lata, liver/kidney involvement possible, splenomegaly possible. primary chancre may still be present. • Demonstration of T. pallidum in clinical specimens by darkfield microscopy, direct fluorescence antibody (DFA-TP), or equivalent methods
When are serologic tests for syphilis highest in titer
secondary syphilis
describe latent syphilis
A stage of infection in which organisms persist in the body without causing symptoms or signs. Only evidence is a positive serologic test. May occur btw 1 and 2 stages, btw 2 and relapses or after 2 syphilis. Early latent 1 yr
describe neurosyphilis
Evidence of central nervous system infection with T. pallidum. Meningitis, ocular involvement and possibly paresis, tabes dorsalis. A reactive serologic test for syphilis and reactive VDRL (Venereal Disease Research Laboratories) in cerebrospinal fluid.
describe Late benign syphilis and cardiovascular syphilis
Inflammatory lesions of the cardiovascular system, skin, and bone. Gummatous lesions. Upper and lower respiratory tracts, mouth, eye, abdominal organs, reproductive organs, lymph nodes, and skeletal muscle may be involved. • Demonstration of T. pallidum in late lesions by fluorescent antibody or special stains, although organisms are rarely visualized in late lesions
Congenital syphilis
Infection in utero with T. pallidum- hepatosplenomegaly, rash, condyloma lata (wart like lesions on genitals), snuffles, jaundice, pseudoparalysis, anemia or edema (nephrotic syndrome and/or malnutrition) Older children >2 may have stigmata -interstitial keratitis, nerve deafness, anterior bowing of shins, frontal bossing, mulberry molars, Hutchinson teeth, saddle nose, rhagades, or Clutton joints
describe stillbirth syphilis
A fetal death that occurs after 20-week gestation or in which the fetus weighs greater than 500 g and the mother had untreated or inadequately treated syphilis
syphilis immunology
Humoral response is not very protective but useful for diagnosis. T cell response is important in immunity to reinfection and protection against tertiary syphilis. Probably responsible for some of the damage in 3 syphilis like gummas
darkfield examination for syphilis diagnosis
A drop of tissue fluid or exudate is placed on a slide and examined with a light. This is still used for the diagnosis of primary syphilis because the antibody based tests may not yet be positive because it takes about 2 weeks for a person to develop antibodies against an antigen.
Syphilis immunofluorescence
Detection of T. pallidum from specimens using fluorescein-labeled anti-treponema serum
List the two types of serological tests for syphilis
Nontreponemal antigen tests and Treponemal antibody tests
describe the nontreponemal antigen tests
Uses reagin, a mixture of cardiolipin, lecithin, and cholesterol which cross-reacts with IgM and IgA antibodies produced by host if infected with T. pallidum. If the host has been infected with T. pallidum, their antibodies react with reagin causing agglutination. VDRL test is read with microscope and RPR test is visible to naked eye
When are antibodies against T. Pallidum found in serum and CSF
antibodies are found in the serum of patients after 2-3 weeks of untreated syphilis infection and in spinal fluid after 4-8 weeks of infection
