Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Spirochetes Dr. Jyotsna Agarwal Dept. Microbiology KGMU Classification of spirochetes • Spirochetes are thin, elongated, spirally twisted, Gram negative bacteria • There are 11 genera in this group • Some are pathogens, but most are free-living, and are actually pretty common in the environment. 3 genera have human pathogens Treponema, Borrelia, leptospira Treponema (25 species)Relatively short, slender, fine spirals. Associated with venereal and non venereal diseases, some are non pathogenic Treponema pallidum causes syphilis- venereal disease- STD. Syphilis - T. pallidum • History- ancient disease, Columbus crew • Reservoir- humans only known natural host. • Name syphilis from a poem describing a shepherd boy • Transmission- sexual route- venereal • Syphilis is not very contagious; a person has 1/10 chance of becoming infected after contact with an infected person • In some stages, it is less contagious • Syphilis is conventionally divided into following stages: Primary, Secondary, Latent, Tertiary –Staging has prognostic and therapeutic implications. Primary syphilis • 5 to 80 days after contact (sexual), a chancre develops at point of contactexternal genitalia • Chancre 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) • 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 Secondary syphilis • 2 - 12 weeks after primary lesion heals, generalized symptoms of disseminated infection occur due to multiplication and dissemination of treponemes • Fever, headache, sore throat and enlarged lymph nodes develop • Papular skin rash develops on body and lesions appear on palms and soles of feet also • Abundant spirochetes in skin lesionsmost infectious stage • Intensity of lesions in secondary syphilis varies • Can Heal spontaneously in months to years • Variable course spontaneous cure latent stage go to 3rd stage Latent Syphilis • Absence of clinical symptoms • 3 possible outcomes Persist for life Tertiary syphilis Cure Tertiary syphilis • 2-20 years later • Steady tissue destruction- Chronic granulomata formation- Gumma, lesions contain very few treponema • Cardiovascular system/CNS • ~1/3 die Late tertiary or quaternary syphilis- • Tabes dorsalis- dorsal column of spinal cord • GPI- dementia Congenital Syphilis • Fetus susceptible after 4th month IU life • 40% fetal death • Hutchinson's Triad peg teeth interstitial keratitis 8th nerve destruction- deafness Treponema pallidum bacteria • It is slender and tightly coiled, measuring 5 to 15 µm long by 0.09 to 0.18µm wide • They have a characteristic motility on dark field microscopy- cork screw • This is due to axial fibrils, similar to flagella, varying numbers • T. pallidum has not been cultured in vivo. • It is rapidly inactivated by: Drying, Heat, Cold • Transmission is by direct contact or congenitally Diagnosis Clinical- based on symptoms, history Laboratory • Darkfield examination Wear gloves, Clean the lesion with saline gauze, press it gently and collect exudate on a slide and examine in darkground microscope. Serologic tests Non Specific/Non treponemal • A reactive material from beef heart called cardiolipin is used as antigen • It reacts with “reagin” antibodies that develop in syphilis • Also called Standard test for Syphilis (STS) VDRL • This is a slide flocculation test to detect antibodies in patients serum using cardiolipin as antigen 1o 1/3 + 2o 95% + latent +/- Other Non treponemal tests • Kahn’s- Tube flocculation test • Wasserman test- Complement fixation • RPR- rapid plasma reagin test Biological false positives- BFP • Acute infections, major trauma, autoimmune conditions like SLE, • Leprosy, malaria Specific - treponemal tests Using T. pallidum antigen to detect antibodies in patients serum • Treponema pallidum immobilization- TPI • Fluorescent treponemal Antibody (FTA) • T pallidum haemagglutination (TPHA) 1o 80% + 2o & 3o >95% + latent >99% + Treatment • Penicillin is drug of choice • Duration of tretment varies according to clinical stage of disease • If allergic to penicillin- Ceftriaxone Summary • • • • • Treponema pallidum bacteria: characters Syphilis disease: mode of transmissison Clinical stages Diagnostic tests: STS / Specific tests Utility of tests / BFP