Free living amoebae - Naegleria , Acanthamoeba and Balamuthia

1. FREE LIVING
AMOEBAE
-DR.M.JANE ESTHER
PG- MICROBIOLOGY

2. PATHOGENIC FREE LIVING
AMOEBAE
Naegleria – Primary Amoebic
Meningoencephalitis (PAM)
Acanthamoeba
 Granulomatous Amoebic Encephalitis (GAE)
 Chronic Amoebic Keratitis (CAK)
Balamuthia mandrillaris

3. NAEGLERIA
 Naegleria fowleri – only pathogenic species
 Fowler and Carter – Australia in 1965
 Habitat: Warm fresh waters

4. MORPHOLOGY
NAEGLERIA
TROPHOZOITE CYST
1. AMOEBOID FORM
2. FLAGELLATE

5. AMOEBOID FORM
 10-20 µm
 Rounded pseudopodia (Lobopodia)
 Spherical nucleus and pulsating vacuoles
 Feeding, growing and replicating form
 Vegetation, mud & water

6. FLAGELLATE FORM
 Transient
 Pear shaped
 2 flagella

7. CYSTS
 7-10 µm
 Smooth double cyst wall
 Resting dormant form
 Resist drying and chlorination

8. LIFE CYCLE
 Infective form :
amoeboid form
 Human infection :
swimming or
diving in water
containing
amoeboid forms
 IP: 1 to 7 days

9. PATHOGENESIS
PRIMARY
AMOEBIC
MENINGO
ENCEPHALITIS
(PAM)

10. DIAGNOSIS - CLINICAL
 Stage 1
 Severe frontal headache
 Fever
 Nausea
 Vomiting
 Stage 2
 Stiff neck
 Seizures
 Altered mental status
 Hallucinations
 Coma

11. LAB DIAGNOSIS
CSF examination
 Cloudy to purulent
 Neutrophil leucocytosis
 Elevated proteins
 Low glucose
 No bacteria

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. TREATMENT
 Amphotericin B – 1mg/kg/day for several days
 Ketoconazole 800 mg daily – oral- 1 month
 New drug : Miltefosine
 Therapeutic hypothermia

14. ACANTHAMOEBA
Species :
 A. culbertsoni
 A. polyphaga
 A.castellani
 A. astromyxis
 A.culbertsoni – immunocompromised
Granulomatous amoebic meningo encephalitis
(GAE)
 A.polyphaga – corneal ulcer

15. DISTRIBUTION & MORPHOLOGY
 Worldwide in distribution
TROPHOZOITE and CYST FORMS are
present
 No flagellate forms
 Both - infective

17. TROPHOZOITE
 Large 20 – 50µm
 Spine like pseudopodia (Acanthopodia)
 Large central dense nucleolus surrounded by halo

18. CYST
 Spherical, 15µm in diameter
 Polygonal , double walled
 Wrinkled outer surface & smooth inner wall

19. HOW DOES IT ENTER???
 Mode of infection :
 Inhalation, ingestion or thru’ traumatised
skin or eyes
CONTACT
LENS
USERS!!!

20. LIFE CYCLE OF ACANTHAMOEBA

21. CHRONIC AMOEBIC KERATITIS
 Entry of cyst through corneal abrasions
 Contact lenses
 Resembles severe herpetic keratitis
 Slow relapsing course
 Severe pain

22. CLINICAL FEATURES
 Blurred vision, redness, foreign body sensation,
photophobia, lacrimation and discharge

23. DIAGNOSIS
 Demonstation of cyst- corneal scrapings by wet
mount, histology & culture
 Corneal scrapings – NA- overlaid with E.coli

24. TREATMENT
Drugs
 propamidine
 Polyhexamethylene biguanide
 Chlorhexidine
 Ketoconazole
Surgical procedures :
 Enucleation of ulcer and corneal transplant

25. GRANULOMATOUS AMOEBIC
ENCEPHALITIS
 Inhalation of dried cysts
 Steroids, diabetes, alcoholism,
immunodeficencies
 Long IP
 Picture : ICSOL with seizures & mental
deterioration

26. DIAGNOSIS
 CSF: Lymphocytic pleocytosis
 CT brain
 IFAT(Indirect fluorescent antibody technique)
 Culture of CSF
 Brain biopsy

27. TREATMENT
 IV Amphotercin B – tried
 Miltefosine

28. 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

29. LIFE CYCLE

30. DIAGNOSIS
 CSF- microscopy & culture
 CSF- only trophozoites
 Brain tissue biopsy – cysts & trophozoites
 Immunoflorescence
 Tissue culture

31. TREATMENT
 Flucytosine
 Pentamidine
 Fluconazole
 Sulfadiazine
 Azithromycn or clarithromycin
 Miltefosine

32. SUMMARY
 Naegleria fowleri : trophozoite & cyst forms, nasal
entry :PAM
 Acanthamoeba : Trophozoite & Cyst forms ,
contact lens, keratitis & GAE
 Balamuthia mandrillaris : Trophozoite & cyst : GAE