Dr. Jyotsna Agarwal Dept. Microbiology KGMU 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.

Treponema, Borrelia, leptospira 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 contact- external 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 lesions- most 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