Treponema genus Flashcards
General Features and habitat of Treponema pallidum
Gram – (but too thin to visualize)
Spirochete- thin, long spiral-shaped
Motile by Endoflagella- used for invasion
Reservoir- human genitals
Virulence Factors of Treponema pallidum
Fibronectin coating- prevent phagocytosis
Outer membrane proteins (TrompI, II and III)- promote adherence
Hyaluronidase- may facilitate perivascular infiltration
Pathogenesis of Treponema pallidum
Sexually transmitted disease (STD) or trans-placental (i.e. congenital form)
Can also be transferred by blood transfusion or organ transplantation
Infectious in 1st, 2nd and 2 first years of latent, after that only in-utero infectious may occur
Incubation period of 1-2 weeks before the first stage
Syphilis primary stage
Ulcus durum- painless, hard chancre, i.e. genital ulcer (unlike H. ducreyi) Usually found on the genitalia; rarely can be in perianal region or oral region
Lymph node enlargement
Lesions lasts about 3-6 weeks and usually progress since left untreated
Diagnosis: Dark-field microscope (DF-M) or fluorescence microscope. Non-specific are 50% negative
Syphilis Secondary stage
Maculopapular rash- copper-color rashes, systemically (all over the body), but best seen on palms and soles (good clues for diagnosis)
Condyloma lata- flat wart-like lesions on mucous membranes
Diagnosis: Both specific and non-specific are positive. Condylama lata is used to diagnosis by DF-M
Syphilis Latent stage
Can be early latent (<1y) or late latent (>1y)- no symptoms but patients are infectious
Diagnosis: Positive serology tests
Syphilis Tertiary stage
Syphilic granulomas or gummas- soft growth with firm necrotic center, that can grow anywhere (e.g. skin, bones…)
Aortitis and aneurysm of ascending aorta- tree barking appearance (destroy the vasa vasorum of the aorta)
Tabes dorsalis- demyelination of nerves in the dorsal column of the spinal cord causing loss of sensation, proprioception and discriminative touch
Argyll Roberston pupils- both pupils react to accommodation but no reaction to light (i.e. don’t constrict); specific sign of neurosyphilis
Diagnosis: Specific tests are positive Non-specific may be negative
Syphilis Congenital stage
Stillbirth- fetal death at week 20-28 of pregnancy (in ~50% of cases)
Early congenital (before the age of 2y): skin lesions, anemia, hepatomegaly
Late congenital:
Interstitial keratitis
Anterior bowing tibia (“sabre-shin”)
Other bone deformations like saddle nose or short maxilla
Hutchinson’s teeth- (notched incisors) and mulberry molars
Deafness
Diagnosis: Serology should revert to negative within 3 months of birth if uninfected
Neurosyphilis
At any stage neurosyphilis can develop (infection involves the central nervous system; symptoms include- encephalopathy, ataxia, dementia, tabes dorsalis, AR pupils etc.)
Diagnosis of Treponema pallidum
Screening in pregnancy is always done; STD can also be checked if suspect
Dark-field Microscope- direct bacteria detection (using silver impregnation from primary lesion)
Rabbit Infection Test (RIT)- inoculation of T. pallidum in rabbit’s testes (unable to culture)
Serology:
Non-specific Tests- detection of Ab (reagin) against non-treponemal lipid type Ag (for
example Cardiolipin, lecithin or cholesterol mixture). Used from 6th week of infection. Aspecific positivity in case of- tumors, viral infections, autoimmune disease, pregnancy Used to determine stage, to detect re-infection or control effectiveness of therapy.
Complement Fixation Test (Wasserman)- blood is mixed with Cardiolipin Ag
VDRL (Venereal Diseases Research Laboratory), screening test for T. pallidum
RPR (Rapid Plasma Reagin)- visible by eye; decrease titer means successful treatment
Specific Tests- detection of Ab (immobilisin) specifically against treponemal Ag
Used for verification and late stage, much more expensive.
False positive tests in case of- Mono (IM), Drug users, RF / RA, Lupus, Leprosy, Lyme
FTA-ABS (Fluorescence Treponemal Antibodies Absorption)- after non-specific tests
TPIT (T. Pallidum Immobilization Test)- Ab from patient’s serum with Ag from rabbit
TPHA (T. Pallidum Hema-Agglutination) or TPPA (T. Pallidum Particle Agglutination)
ELISA- recombinant antigen to detect the specific Ab (immobilisin)
Western Blot- immunoblot stripes with antigen, used to confirm ELISA
Treatment of Treponema pallidum
Penicillin (at all stages)- if allergic use Erythromycin or Tetracycline
Jarisch-Hexheimer reaction may occur hours after treatment. The dying spirochetes
release a lot of LPS causing increase in cytokines. This leads to fever, chills, headache
Prevention of Treponema pallidum
Penicillin for pregnant women- prevent congenital form (no vaccination)
Treponema Genus and Non-venereal Treponemal Diseases: (Treponematosis)
Treponema pallidum spp. endemicum
Treponema pallidum spp. pertenue
Treponema carateum
Treponema vincentii
Treponema pallidum spp. endemicum
A.K.A endemic syphilis- found in Africa, Asia, Australia
Spread person to person by contaminated eating utensils
Initial oral lesions, secondary skin lesions
Treponema pallidum spp. pertenue
Endemic- South America, Central Africa, Southeast Asia
Granulomatosous disease (granulomas formation)
Skin lesions
