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Free living amoebae

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Free living amoebae - Naegleria , Acanthamoeba and Balamuthia

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Free living amoebae

  1. 1. FREE LIVING AMOEBAE -DR.M.JANE ESTHER PG- MICROBIOLOGY
  2. 2. PATHOGENIC FREE LIVING AMOEBAE Naegleria – Primary Amoebic Meningoencephalitis (PAM) Acanthamoeba  Granulomatous Amoebic Encephalitis (GAE)  Chronic Amoebic Keratitis (CAK) Balamuthia mandrillaris
  3. 3. NAEGLERIA  Naegleria fowleri – only pathogenic species  Fowler and Carter – Australia in 1965  Habitat: Warm fresh waters
  4. 4. MORPHOLOGY NAEGLERIA TROPHOZOITE CYST 1. AMOEBOID FORM 2. FLAGELLATE
  5. 5. AMOEBOID FORM  10-20 µm  Rounded pseudopodia (Lobopodia)  Spherical nucleus and pulsating vacuoles  Feeding, growing and replicating form  Vegetation, mud & water
  6. 6. FLAGELLATE FORM  Transient  Pear shaped  2 flagella
  7. 7. CYSTS  7-10 µm  Smooth double cyst wall  Resting dormant form  Resist drying and chlorination
  8. 8. LIFE CYCLE  Infective form : amoeboid form  Human infection : swimming or diving in water containing amoeboid forms  IP: 1 to 7 days
  9. 9. PATHOGENESIS PRIMARY AMOEBIC MENINGO ENCEPHALITIS (PAM)
  10. 10. DIAGNOSIS - CLINICAL  Stage 1  Severe frontal headache  Fever  Nausea  Vomiting  Stage 2  Stiff neck  Seizures  Altered mental status  Hallucinations  Coma
  11. 11. LAB DIAGNOSIS CSF examination  Cloudy to purulent  Neutrophil leucocytosis  Elevated proteins  Low glucose  No bacteria
  12. 12.  Wet film – Trophozoites  Autopsy – trophozoites in brain histologically  Wright or Giemsa stain – Trophozoites  Fluorescent Ab staining – Amoeba  Culture – Agar seeded with Escherichia coli
  13. 13. TREATMENT  Amphotericin B – 1mg/kg/day for several days  Ketoconazole 800 mg daily – oral- 1 month  New drug : Miltefosine  Therapeutic hypothermia
  14. 14. ACANTHAMOEBA Species :  A. culbertsoni  A. polyphaga  A.castellani  A. astromyxis  A.culbertsoni – immunocompromised Granulomatous amoebic meningo encephalitis (GAE)  A.polyphaga – corneal ulcer
  15. 15. DISTRIBUTION & MORPHOLOGY  Worldwide in distribution TROPHOZOITE and CYST FORMS are present  No flagellate forms  Both - infective
  16. 16. TROPHOZOITE  Large 20 – 50µm  Spine like pseudopodia (Acanthopodia)  Large central dense nucleolus surrounded by halo
  17. 17. CYST  Spherical, 15µm in diameter  Polygonal , double walled  Wrinkled outer surface & smooth inner wall
  18. 18. HOW DOES IT ENTER???  Mode of infection :  Inhalation, ingestion or thru’ traumatised skin or eyes CONTACT LENS USERS!!!
  19. 19. LIFE CYCLE OF ACANTHAMOEBA
  20. 20. CHRONIC AMOEBIC KERATITIS  Entry of cyst through corneal abrasions  Contact lenses  Resembles severe herpetic keratitis  Slow relapsing course  Severe pain
  21. 21. CLINICAL FEATURES  Blurred vision, redness, foreign body sensation, photophobia, lacrimation and discharge
  22. 22. DIAGNOSIS  Demonstation of cyst- corneal scrapings by wet mount, histology & culture  Corneal scrapings – NA- overlaid with E.coli
  23. 23. TREATMENT Drugs  propamidine  Polyhexamethylene biguanide  Chlorhexidine  Ketoconazole Surgical procedures :  Enucleation of ulcer and corneal transplant
  24. 24. GRANULOMATOUS AMOEBIC ENCEPHALITIS  Inhalation of dried cysts  Steroids, diabetes, alcoholism, immunodeficencies  Long IP  Picture : ICSOL with seizures & mental deterioration
  25. 25. DIAGNOSIS  CSF: Lymphocytic pleocytosis  CT brain  IFAT(Indirect fluorescent antibody technique)  Culture of CSF  Brain biopsy
  26. 26. TREATMENT  IV Amphotercin B – tried  Miltefosine
  27. 27. BALAMUTHIA MANDRILLARIS  Leptomyxoid free living amoeba  GAE in AIDS patients  Has trophozoite & cyst forms  No flagellated form  Life cycle & mode of infection – similar to Acanthamoeba
  28. 28. LIFE CYCLE
  29. 29. DIAGNOSIS  CSF- microscopy & culture  CSF- only trophozoites  Brain tissue biopsy – cysts & trophozoites  Immunoflorescence  Tissue culture
  30. 30. TREATMENT  Flucytosine  Pentamidine  Fluconazole  Sulfadiazine  Azithromycn or clarithromycin  Miltefosine
  31. 31. SUMMARY  Naegleria fowleri : trophozoite & cyst forms, nasal entry :PAM  Acanthamoeba : Trophozoite & Cyst forms , contact lens, keratitis & GAE  Balamuthia mandrillaris : Trophozoite & cyst : GAE

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