2 Classification of spirochetes Spirochetes are thin, elongated, spirally twisted, Gram negative bacteriaThere are 11 genera in this groupSome are pathogens, but most are free-living, and are actually pretty common in the environment.
3 Treponema, Borrelia, leptospira 3 genera have human pathogensTreponema, Borrelia, leptospiraTreponema (25 species)-Relatively short, slender, fine spirals.Associated with venereal and non venerealdiseases, some are non pathogenicTreponema pallidum causes syphilis- venereal disease- STD.
4 Syphilis - T. pallidum History- ancient disease, Columbus crew Reservoir- humans only known natural host.Name syphilis from a poem describing a shepherd boy
5 Transmission- sexual route- venereal Syphilis is not very contagious; a person has 1/10 chance of becoming infected after contact with an infected personIn some stages, it is less contagious
6 Syphilis is conventionally divided into following stages: Primary, Secondary, Latent, TertiaryStaging has prognostic and therapeutic implications.
7 Primary syphilis5 to 80 days after contact (sexual), a chancre develops at point of contact- external genitaliaChancre is an inflammatory lesion containing spirochetes & lymphocytes.It is painless, well circumscribed, indurated, heals spontaneously after ~10 – 40 days leaving a thin scar.(also called hard chancre)
8 Regional lymph nodes are enlarged and non tender Even before appearance of chancre, treponema spread from site of entry via blood/lymph.Multiple chancre may be seen in immunodefficient patients.Once this heals patient remains asymptomatic till secondary stage
9 Secondary syphilisweeks after primary lesion heals, generalized symptoms of disseminated infection occur due to multiplication and dissemination of treponemesFever, headache, sore throat and enlarged lymph nodes developPapular skin rash develops on body and lesions appear on palms and soles of feet also
10 Abundant spirochetes in skin lesions- most infectious stage Intensity of lesions in secondary syphilis variesCan Heal spontaneously in months to yearsVariable coursespontaneous curelatent stagego to 3rd stage
11 Latent Syphilis Absence of clinical symptoms 3 possible outcomes Persist for lifeTertiary syphilisCure
12 Tertiary syphilis 2-20 years later Steady tissue destruction- Chronic granulomata formation- Gumma, lesions contain very few treponemaCardiovascular system/CNS~1/3 die
13 Late tertiary or quaternary syphilis- Tabes dorsalis- dorsal column of spinal cordGPI- dementia
14 Congenital Syphilis Fetus susceptible after 4th month IU life 40% fetal deathHutchinson's Triadpeg teethinterstitial keratitis8th nerve destruction- deafness
16 Treponema pallidum bacteria It is slender and tightly coiled, measuring 5 to 15 µm long by 0.09 to 0.18µm wideThey have a characteristic motility on dark field microscopy- cork screwThis is due to axial fibrils, similar to flagella, varying numbers
17 T. pallidum has not been cultured in vivo. It is rapidly inactivated by:Drying, Heat, ColdTransmission is by direct contact orcongenitally
20 Diagnosis Clinical- based on symptoms, history Laboratory Darkfield examinationWear gloves, Clean the lesion with saline gauze, press it gently and collect exudate on a slide and examine in darkground microscope.
21 Serologic tests Non Specific/Non treponemal A reactive material from beef heart called cardiolipin is used as antigenIt reacts with “reagin” antibodies that develop in syphilisAlso called Standard test for Syphilis(STS)
22 VDRLThis is a slide flocculation test to detect antibodies in patients serum using cardiolipin as antigen1o /3 + 2o % + latent +/-
23 Other Non treponemal tests Kahn’s- Tube flocculation testWasserman test- Complement fixationRPR- rapid plasma reagin testBiological false positives- BFPAcute infections, major trauma, autoimmune conditions like SLE,Leprosy, malaria
24 Specific - treponemal tests Using T. pallidum antigen to detect antibodies in patients serumTreponema pallidum immobilization- TPIFluorescent treponemal Antibody (FTA)T pallidum haemagglutination (TPHA)1o % +2o & 3o >95% +latent >99% +
25 Treatment Penicillin is drug of choice Duration of tretment varies according to clinical stage of diseaseIf allergic to penicillin- Ceftriaxone
26 Summary Treponema pallidum bacteria: characters Syphilis disease: mode of transmissisonClinical stagesDiagnostic tests: STS / Specific testsUtility of tests / BFP