Spirochetes & Gram Negative Cocci

1. Spirochetes & Gram Negative Cocci Professor Sudheer Kher

2. Learning Objectives • Enlist medically important GNCs & Spirochetes • List important virulence factors • Describe the mechanism of development of infection by GNCs • List pathogenicity of meningococci & gonococci • List spirochetes and diseases caused by them • List Lab tests for diagnosis of syphilis Resources - Ananthanarayan Ch 25, 42

3. Spirochete Axial filament Treponema pallidum Syphilis Chancre Primary lesion Darkfield microscopy Secondary Lesion Tertiary Lesion Anti-cardiolipin antibodies VDRL/RPR tests Borrelia burgdorferi Lyme disease Relapsing fever Vincent’s angina Leptospira (leptospirosis, Weil’s Disease) Neisseria Thayer Martin medium N. gonorrhoeae Gonorrhea N. meningitidis Meningitis Fulminant meningococcemia Key Words

4. SPIROCHETES Treponema, Borrelia and Leptospira

5. Spirochetes • Gram negative • Long, thin, helical, motile • Axial filaments • Locomotion • Between peptidoglycan layer/outer membrane • Runs parallel

6. Treponema pallidum • Transmission • genital/genital • in utero or during birth • Pathogenicity • Syphilis • Chronic, Slowly progressing

7. Primary lesion • - chancre • 10 to 60 days • area of ulceration & inflammation • many organisms • Secondary (2-10 weeks later) • systemic spread • flu-like symptoms • skin, particularly • many organisms • Tertiary • several years later • rare • skin, central nervous system • delayed hypersensitivity • few organisms • control by immune response Syphilis

8. Microbiological diagnosis • Not culturable • Dark field microscopy • Actively motile organisms • Brightly lit against dark backdrop • Light shines at an angle • Reflected from thin organisms • Enters objective • Silver impregnation Fontana / Levaditi stain • Fluorescence microscopy antibody staining

9. Secondary and Tertiary Syphilis- serology • Screening method • Antibodies to cardiolipin VDRL / RPR Tests • False positive result possible • Specific diagnosis • Antibodies to treponemal antigen TPHA • No false positives • Once positive remain so for many years.

10. Borrelia burgdorferi and Lyme disease Ixodes scapularis, tick vector for Lyme disease. Also known as Ixodes dammini. CDC Lyme Disease erythematous rash

11. Lyme disease - symptoms • bacteremia • acute • arthritis • cardiac • neurologic • chronic • weeks, months later Atick bite leads to transmission of B. burgdorferi

12. Therapy • Early antibiotic therapy • Curable • Penicillin • Tetracycline • Late antibiotic administration • Ineffective

13. Diagnosis A physicians dilemma • Serum antibodies to B. burgdorferi. • Laboratory strains • Grow extremely slowly • Tissue culture media • Not bacteriological media • Patient body fluids/tissue sample • Almost never growth • Acute • responds to antibiotic • antibodies not detectable • Late diagnosis • not curable • antibodies detectable

14. Relapsing fever Diagnosis • Transmission • Lice-B. recurrentis • Human, primary host • Immune response develops • Fever disappears • New antigens expressed • No immunity • Disease reappears • No culture • No serological test • Detected - blood smear

15. Borrelia vincentii • Extremely painful condition of oral cavity • Symbiotic infection with Fusobacterium fusiformis • Normal inhabitant of mouth • Can cause Vincent’s Angina

16. Leptospirosis • Symptoms • flu-like • severe systemic disease • Liver • kidney • Brain • Eye

17. Transmission • Infected urine • rodents • farm animals • Water • Through broken skin.

18. Laboratory Diagnosis • Serology • Most readily culturable of spirochetes • culture still extremely difficult

20. Neisseria • Gram negative • Diplococci (pairs of cocci) • Oxidase positive • Culture • Thayer Martin. • selective • chocolate agar • heated blood (brown)

21. N. gonorrhoeae the “Gonococcus" • Exclusive disease of humans • Gonorrhea • Urethritis in men • Endo-cervicitis in women • Second most common venereal disease • Ophthalmia neonatorum – Non venereal transmission • Crede’s prophylaxis – Silver nitrate eye drops

22. Smear • Polymorphonuclear cell • Gram negative cocci • Many in cells

23. Dissemination -gonococci • Gonoccocal arthritis • “septic” arthritis • Dermatitis

24. Antibiotic therapy • βlactamase-resistant cephalosporin • e.g. ceftriaxone • resistant strains • common • produceβ lactamases • destroy penicillin

25. Pathogensis • Adhesion to genital epithelium • Outer membrane • Pili (Fimbrae) • Antigenicity • highly variable among strains • No vaccine • IgA protease • also N. meningitidis

26. N. gonorrhoeae • Tissue injury • lipopolysaccharide • peptidoglycan • OnlyFimbriated strains cause disease

27. N. meningitidis(the “Meningococcus")

28. N. meningitidis • Resides in humans only • Usually sporadic cases • mostly young children • Outbreaks • Adults • Crowded conditions • e.g. Army barracks, Dorms

29. Neisseriameningitidis • Upper respiratory tractinfection • Adhesion pili • Bloodstream Brain

30. Meningococcal meninigitis • Second most common meningitis • pneumococcus, most common • Fatal if untreated • Responds well to antibiotic therapy • penicillin • Also causes fulminant Meningococcemia

31. Fulminant meningococcal septicaemia presents with: • Extensive haemorrhage into the skin • Hypotension • Shock • Confusion • Coma • DIC • Death (within a few hours of the onset of symptoms) • If adrenals are involved it is called as -Waterhouse-Friderichsen Syndrome (WFS)

32. Laboratory Diagnosis • Spinal fluid • Gram negative diplococci • within polymorphonuclear cells • Meningococcal antigens by CIEP • Culture • Blood agar, Chocolate agar

33. Virulence factor -Capsule • Capsule • inhibit phagocytosis • Anti-capsular antibodies • stop infection • Antigenic variation • sero-groups • Vaccine • multiple sero-groups