3 General characters (free-living) Opportunistic pathogens in human (under unknown conditions).Widely distributed in soil and water.Naegleria fowleri and Acanthamoeba castellani
4 FeaturesIntestinal amoebaeFree-living amoebaeHabitatPathogenicityFlagellated formsIntestinePathogenic (diseases in colon, liver and other extra-intestinal sites)AbsentSoil and waterOpportunistic (affect CNS, cornea and skin)May be present
5 Naegleria fowleri Morphology Amoebo-flagellate Three forms Amoeboid Free-living in fresh or brackish water (lake, river and ponds) and soil.MorphologyAmoebo-flagellateThree formsAmoeboidFlagellateCyst
6 Amoeboid (Trophozoite ) Rounded / elongated 15-30u.The infective stageSingle nucleusFeed and divide by binary fission.Can be transformed into flagellate and cyst formFound in CSF and tissue
7 Flagellate form Elongated / pear shaped Anterior nucleus Two free flagellaFound in water at ̊CNon feeding & non dividingNever present in tissueCan be transformed to amoeboid form
8 Cyst form Rounded with single nucleus 7-15u Thick double cyst wall Found in soilNever in tissue
11 InfectionSwimming or diving in warm water(aspiration of water) contaminated with N. Fowleri (trophzoite) esp. in summer.Trophozoit is neurotropic ( nose- olf mucosa-olf pulb-cribriform plate-subarachinoid space).1ry amoebic meningoencephalitis (fatal)- haemorrhagic inflammation- necrosis of brain tissue- Amoeba is the only form detected in brain tissue, flagellates and cysts never found in tissue or CSF
12 1ry amoebic meningoencephalitis Children and young adultPreviously healthyHistory of bathing, swimming, diving or playing in warm stagnant, fresh waterFew days to 2 weeks prior to onset of symptomsHeadache, tempStiff neck, mental status changes and seizures
13 Diagnosis History of swimming in pools or natural warm water Clinical pictureCSF fresh film (amoeboid), purulent but no bacteria. Increase pressure, PMN cells , increase protein, presence of RBCsStained : giemsa, trichrome and Wright stainsCulture on non-nutrient agar plate seeded with E. ColiLeucocytosis in peripheral blood (25,000)Serodiagnosis not useful, PCR, CT
14 Treatment of PAM No satisfactory treatment. Hospitalization Palliative treatmentAmphotericin B “drug of choice”.Act on amoebic plasma membrane .IV or intrathecalMiconazole, rifampin and sulfisoxazole.
15 Prevention Public education Chlorination of swimming pools and public water public supplies
16 Acanthamoeba castellani In dust, soil, sand, river ponds and tape water.2 forms: Trophozoite and Cyst (infective stages).Both stages may exist in the environment and tissues.In man : affect CNS, eye, skin and lungs.Opportunistic parasite, causes severe disease in immunocompromised.
17 Trophozoite Variable in shape 10-40 u in diameter slender spine-like projections of plasma membrane (acantopodia).Contractile vacuoleNucleus with large central karyosome
18 cyst Polygonal, spherical; or star- shaped. 15-20u in diameter Double wall, outer smooth irregular ectocyst and inner rough polyhedral endocyst with many pores (osteoles)
20 Inhalation of aerosol or dust containing cyst or trophozoites. Portal of entrySkin, mucosal ulcer, lung inhalation or cornea.Mode of infectionInhalation of aerosol or dust containing cyst or trophozoites.Invasion through broken skin.Corneal trauma, prolonged use of contact lenses.
22 Diseases Affects immunocompromised 1) Granulomatous amoebic encephalitis:Affects immunocompromisedCourse is sub-acute or chronic (from weeks to years)Reaches brain through blood supply from lung or skin abrasions.forms focal granuloma at deeper brain tissuesHeadache, seizures, stiff neck, nausea and vomitingTissues contain Trophozoite, cysts and multinucleate giant cells.
23 2) Amoebic keratitis:Direct contact of cornea with contaminated water or contact lensChronic progressive, ulcerative keratitisSevere unilateral ocular painVision is affected, neutrophils infiltrationsLoss of visionTrophozoite and cyst are present in corneal tissue3) chronic granulomatous skin ulcers
24 Laboratory diagnosis Brain tissue and CSF Trophozoite and cyst Culture on non nutrient agarCSF elevated protein, normal or decrease glucose.Corneal scraping (direct saline wet mount)Culture of contact lens saline or corneal scrapingCT multiple brain focal lesions.IFA of tissue.
25 Treatment Health education Avoid swimming in stagnant water No effective therapy is availableSulfadiazine, penicillin and chloramophenicol.In keratitis, drug is effective (ketoconazole) with topical application ( miconazole) followed by keratoplasty.PreventionHealth educationAvoid swimming in stagnant waterUse of proper contact lens fluid
26 CharactersNaegleriaAcanthamoebaFormsTrophozoiteCyst3 stagesTrophozoite, flagellate and cystActively motileRoundTwo onlyTrophozoite and cystSluggishly motilepolyhedral