Transcript Spirochetes
Spiral Organisms Treponema carateum: pinta Pinta (non-venereal – erythematous skin lesions only) pertenue: yaws (non-venereal – papilloma skin lesions) vincentii: ANUG (trench mouth – mixed anaerobic infection) denticola: periodontitis interrogans: leptospirosis Borrelia Acute necrotizing ulcerative gingivitis (ANUG) Leptospira pallidum: syphilis Bejel (subsp. endemicum - non-venereal variant – African, etc.) recurrentis: epidemic relapsing fever hermsii: endemic relapsing fever burgdorferi: Lyme disease Spirillum (rat bite fever) minus 20/ 02/ 08 SPIROCHETES 20/ 02/ 08 Key Words Spirochete Axial filament Darkfield microscopy Treponema pallidum Syphilis Hard painless chancre Primary lesion Secondary Lesion Tertiary Lesion Anti-cardiolipin antibodies 20/ 02/ 08 VDRL, RPR, TPHA, FTAABS Borrelia burgdorferi - Lyme disease Relapsing fever (other borrelia) Leptospira (leptospirosis)Weil’s Disease General Characteristics Elongated, motile (endoflagella- axial filament), spiral bacteria Structurally complex – central protoplasmic cylinder bounded by a cytoplasmic membrane & cell wall of similar structure to that of Gram –ve bacteria. 20/ 02/ 08 General Characteristics Larger spirochetes are gram negative, others are too thin to be seen with light microscope. Seen under Dark Ground Microscope by staining with silver 20/ 02/ 08 What are Spirochetes? Small, motile, slender, helically coiled, flexible bacteria Require special staining techniques; Gram-stain ineffective 20/ 02/ 08 Dark field Fluorescent Silver stain for tissue Wright’s or Giemsa may detect Borrelia in blood smears Classification of Spirochetes Human pathogens belong to following 3 genera: 1. 2. 3. Treponema Leptospira Borrelia Others (saprophytes) are found in water, sewage and in mouth & genital tracts of humans. 20/ 02/ 08 Comparative Morphology 20/ 02/ 08 Treponema Main treponemes are: T. pallidum - Syphilis:Venereal (sexual) disease T. pertenue - Yaws Non venereal T. carateum - Pinta disease All three species are morphologically identical 20/ 02/ 08 Treponema pallidum Characteristics : Discovered by Schaudin & Hoffman in 1905. Better seen under DGM - prolonged Giemsa stain, Silver impregnation method Fontana’s – smears Levaditi’s – tissue sections 20/ 02/ 08 Characteristics of T.pallidum Morphology – thin, 10μ with tapering ends Culture – 1. 2. 3. 20/ 02/ 08 Do not grow on artificial media. Virulent strains can be maintained in rabbit testis by serial passages e.g. Nichol’s strain – used for diagnosis & research Reiter’s strain – nonpathogenic strain cultivated for diagnosis. Characteristics of T.pallidum Very delicate, easily killed by drying or heating at 42C for an hr. Antigenicity – 3 types of Abs are produced. 1. 2. 3. 20/ 02/ 08 Non specific - Reagin Ab Group specific – found in T.pallidum & Reiter strains. Species specific – polysaccharide Ag of T.pallidum Pathogenicities Causes Syphilis which can be: 1. 2. 3. 20/ 02/ 08 Venereal Congenital Non venereal Venereal Syphilis Sexually transmitted disease. Entry through minute abrasions on mucosa or skin. Incubation period - about a month (10 to 90 days). Infectivity is maximum during first 2 years of disease – primary, secondary & early latent stages 20/ 02/ 08 Stages of venereal syphilis Primary syphilis – 1. 2. 20/ 02/ 08 hard chancre on genitals: painless, avascular, circumscribed, indurated & ulcerated lesion; covered with a thick glairy exudate rich in spirochetes Heals spontaneously in 10-40 days Primary Lesions 20/ 02/ 08 Stages of venereal syphilis Secondary syphilis – 1. 2. 3. 4. Most infectious stage Sets in 2-6 months after 1 lesion heals. Pt is asymptomatic but widespread dissemination occurs via blood Maculopapular skin rashes on the body, mucous patches in the oropharyngeal area & condylomata at mucocutaneous junctions 20/ 02/ 08 Stages of venereal syphilis Latent syphilis – quiescent stage which follows secondary stage Tertiary syphilis – after 10 to 20years, cardiovascular lesions like aneurysm, aortitis Late tertiary or quaternary syphilis – neurosyphilis : tabes dorsalis or general paralysis of insane 20/ 02/ 08 20/ 02/ 08 Congenital syphilis Mother to fetus via placenta After 4th month of gestation Clinical features – keratitis, saddle shaped nose, Hutchinsons teeth, 8th nerve deafness. Non venereal syphilis In doctors & nurses Rarely by blood transfusion 20/ 02/ 08 Saddle shaped nose Hutchinsons teeth 20/ 02/ 08 Laboratory Diagnosis Microscopy – Dark ground(DGM) - used in 1 & 2 syphilis Silver staining Direct fluorescent Ab test (DFA – TP) 1. 2. 3. Serology – mainstay of diagnosis 1. 2. 3. 20/ 02/ 08 Non specific test/ standard tests for syphilis Group specific test Specific tests Non specific / Standard tests Test for reagin Ab using cardiolipin Ag. 1. 2. 3. 4. 20/ 02/ 08 Wasserman complement fixation test Kahn flocculation test VDRL (Venereal Disease Research Laboratory) test RPR (Rapid Plasma Reagin) test Biological false positive reactions are seen in 1% of human sera Group specific test Using Reiter strain Ag – Reiter protein CFT Specific tests Using Nichol’s strain 1. 2. 3. 4. 20/ 02/ 08 T. pallidum immobilisation (TPI) test T. pallidum haemagglutination test (TPHA) Fluorescent treponemal Ab absorption test (FTAABS) – very specific, standard reference test T. pallidum enzyme immunoassay(TP-EIA) Non-treponemal False Positives (1-2%; generally low titer) Autoimmune disease Injection drug use TB Vaccinations Pregnancy Infectious mononucleosis HIV Rickettsial infections Spirochetal infections other than pallidum Bacterial endocarditis 20/ 02/ 08 Non-treponemal reactivity diminishes over time (aside: also after successful treatment) 20/ 02/ 08 Evaluating Serologies Non-treponemal antibodies develop 4-8 weeks after infection (within 2 weeks of chancre formation in 70% of patients) 4-fold increase in titer may be seen in early syphilis; in secondary, titers are often high Quantitative tests are used to assess treatment; 4fold decreases demonstrate adequate therapy. Increases after treatment suggest reinfection or relapse. Positive CNS reactivity indicates neurosyphilis Confirm positives with treponemal-specific tests 20/ 02/ 08 Syphilis Serologic Testing 20/ 02/ 08 Treatment Penicillin is the drug of choice 2nd line- Erythromycin, Tetra/ Doxycycline Neurosyphilis - Ceftriaxone 20/ 02/ 08 CDC-Recommended Treatments for Syphilis (2002) Primary, secondary, or early latent syphilis * Late latent syphilis, syphilis of unknown duration, tertiary syphilis Recommended: benzathine penicillin G, 2.4 million units in a single dose, intra muscularly Penicillin allergy: doxycycline, 100 mg by mouth twice daily for 14 days Recommended: benzathine penicillin G, 2.4 million units weekly for 3 weeks, in tramuscularly Penicillin allergy: doxycycline, 100 mg by mouth twice daily for 28 days Neurosyphilis, syphilitic eye disease, syphilitic auditory disease Recommended: Aqueous crystalline penicillin G, 18-24 million units per day ad ministered as 3-4 million units intravenously every 4 hours or continuous in fusion for 10-14 days Alternative: procaine penicillin 2.4 million units intramuscularly once daily plus probenecid 500 mg by mouth 4 times a day, both for 10-14 days *Latent syphilis is defined as seroreactivity without other evidence of disease. Early latent syphilis is diagnosed in patients infected within the preceding year as defined by 1 of the following: (1) a documented seroconversion; (2) unequivocal symptoms of primary or secondary syphilis; or (3) a sex partner documented to have primary, secondary, or early latent syphilis. Pregnant women should not be treated with doxycycline. Patients with non–life-threatening allergies to penicillin should ideally be desensitized. Patients with serious allergies to sulfonamides should not be treated with probenecid-containing regimens. 20/ 02/ 08 Prevention and Control Screening All pregnant woman at first prenatal visit Individuals with other STDs High risk behaviors (drug use, prostitution, etc.); again at 28 weeks gestation if pregnant Exposure Reporting of contacts and tracing of sexual partners Education 20/ 02/ 08