SpirochetesSpirochetes

Dr. Jyotsna AgarwalDr. Jyotsna Agarwal

Dept. MicrobiologyDept. Microbiology

KGMUKGMU

Classification of spirochetesClassification 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 pathogensTreponema, Borrelia, leptospira

Treponema (25 species)-Relatively short, slender, fine spirals.Associated with venereal and non venerealdiseases, 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 Syphilis is conventionally divided into following stages:following stages:

Primary, Secondary, Latent, TertiaryPrimary, 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- Abundant spirochetes in skin lesions- most infectious stagemost infectious stage

• Intensity of lesions in secondary syphilis Intensity of lesions in secondary syphilis variesvaries

• Can Heal spontaneously in months to Can Heal spontaneously in months to yearsyears

• 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

DiagnosisDiagnosis

Clinical- based on symptoms, history Clinical- based on symptoms, history

LaboratoryLaboratory

• Darkfield examinationDarkfield examination

Wear gloves, Clean the lesion with Wear gloves, Clean the lesion with saline gauze, press it gently and saline gauze, press it gently and collect exudate on a slide and examine collect exudate on a slide and examine in darkground microscope.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

11oo 1/3 + 1/3 +22o o 95% +95% +latent +/-latent +/-

Other Non treponemal tests• Kahn’s- Tube flocculation test• Wasserman test- Complement

fixation• RPR- rapid plasma reagin testBiological false positives- BFP• Acute infections, major trauma,

autoimmune conditions like SLE, • Leprosy, malaria

Specific - treponemal testsSpecific - treponemal tests

Using T. pallidum antigen to detect antibodies in Using T. pallidum antigen to detect antibodies in patients serum patients serum

• Treponema pallidum immobilization- TPITreponema pallidum immobilization- TPI• Fluorescent treponemal Antibody (FTA)Fluorescent treponemal Antibody (FTA)• T pallidum haemagglutination (TPHA)T pallidum haemagglutination (TPHA)

11oo 80% + 80% +22oo & 3 & 3oo >95% + >95% +latent >99% +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