FREE LIVING AMEBAEFREE LIVING AMEBAE

LECTURER:LECTURER:SR. NORAZSIDASR. NORAZSIDA

INTRODUCTIONINTRODUCTION

A large and diverse group of protozoan A large and diverse group of protozoan organisms.organisms.Inhabit fresh and salt water.Inhabit fresh and salt water.Decaying organic matter and damp soil.Decaying organic matter and damp soil.2 potential pathogens r: 1) 2 potential pathogens r: 1) Naegleria Naegleria fowlerifowleri 2) 2) Acanthamoeba sp.Acanthamoeba sp.

N. fowleriN. fowleri

MorphologyMorphologyFamily VahlkampfiidaeFamily VahlkampfiidaeAmeboflagellates – having both an ameboid and Ameboflagellates – having both an ameboid and flagellate stage in their life.flagellate stage in their life.Agent of primary amebic meningoencephalitis Agent of primary amebic meningoencephalitis (PAM) or Naegleriasis.(PAM) or Naegleriasis.Since 1965, 140 cases have been reported Since 1965, 140 cases have been reported world wide.world wide.Risk group: healthy children and young adults Risk group: healthy children and young adults with a history of swimming or diving in fresh or with a history of swimming or diving in fresh or brackish water.brackish water.Sources of infection: contaminated swimming Sources of infection: contaminated swimming pools, stagnant ponds, freshwater lakes and pools, stagnant ponds, freshwater lakes and streams, thermal springs and spas.streams, thermal springs and spas.

Drought and elevated temperatures Drought and elevated temperatures increase concentrations of increase concentrations of N. fowleriN. fowleri. . Why? Bcoz, they feed on large Why? Bcoz, they feed on large populations of bacteria in these warmed populations of bacteria in these warmed water souces. water souces. Transmitted via inhalation of contaminated Transmitted via inhalation of contaminated dust.dust.Transmission: nasal instillation Transmission: nasal instillation follows follows olfactory nerve olfactory nerve to CNS to CNSTrophozoite : 7-20Trophozoite : 7-20µm, large, broad µm, large, broad pseudopods, single nucleus, large central pseudopods, single nucleus, large central karyosome.karyosome.

Life cycleLife cycleConsists of 3 stages: 1) an amebic trophozoite (the only Consists of 3 stages: 1) an amebic trophozoite (the only stage that exist in human) 2) a biflagellate form 3) cyststage that exist in human) 2) a biflagellate form 3) cyst

TRANSMISSION TRANSMISSION

PATHOGENESISPATHOGENESIS

The incubation period is generally 3-7 The incubation period is generally 3-7 days accompanied by the prodromal days accompanied by the prodromal symptoms of headache and fever.symptoms of headache and fever.Rapidly progress to frank meningitis with Rapidly progress to frank meningitis with the onset of nausea and vomiting (stiff the onset of nausea and vomiting (stiff neck), confusion and coma.neck), confusion and coma.Death usually occurs in 3-6 days following Death usually occurs in 3-6 days following the onset of these serious symptoms.the onset of these serious symptoms.

Primary amebic meningoencephalitis Primary amebic meningoencephalitis PAMPAM

1-14 days incubation period 1-14 days incubation period symptoms usually within a few days after symptoms usually within a few days after swimming in warm still waters swimming in warm still waters infection believed to be introduced through nasal infection believed to be introduced through nasal cavity and olfactory neuroepithelium cavity and olfactory neuroepithelium symptoms include headache, lethargy, symptoms include headache, lethargy, disorientation, coma disorientation, coma rapid clinical course, death in 4-5 days after rapid clinical course, death in 4-5 days after onset of symptoms onset of symptoms trophozoites can be detected in spinal fluid, but trophozoites can be detected in spinal fluid, but diagnosis is usually at autopsy diagnosis is usually at autopsy

LABORATORY DIAGNOSISLABORATORY DIAGNOSISFinding motile trophozoites in:Finding motile trophozoites in:

-saline and wet preps of fresh spinal fluid-saline and wet preps of fresh spinal fluid-nasal discharge-nasal discharge-Tissue biopsy-Tissue biopsy

Induced within 2-20 hours by transferring Induced within 2-20 hours by transferring the ameboid form from tissue or CSF to the ameboid form from tissue or CSF to water and incubating at 37water and incubating at 3700C.C.Cultivation techniqueCultivation techniquePCRPCRIndirect fluorescent antibody procedures.Indirect fluorescent antibody procedures.

TREATMENTTREATMENT

Amphotericin BAmphotericin BCombination treatments:Combination treatments:

- Amphotericin B + miconazoleAmphotericin B + miconazole- Amphotericin B + rifambinAmphotericin B + rifambin

PREVENTIONPREVENTION

Public and private swimming pools, hot Public and private swimming pools, hot tubs, and baths should be properly tubs, and baths should be properly maintained and adequately chlorinated to maintained and adequately chlorinated to prevent growth of the organism.prevent growth of the organism.

Acanthamoeba sp.Acanthamoeba sp.

MorphologyMorphologyFamily of Ancanthamoebidae.Family of Ancanthamoebidae.Never produce flagella.Never produce flagella.Produce a chronic infection of the CNS: Produce a chronic infection of the CNS: Granulomatous amebic encephalitis (GAE).Granulomatous amebic encephalitis (GAE).Also caused a keratitis and skin ulcers.Also caused a keratitis and skin ulcers.Risk group: immunocompromised, chronically ill.Risk group: immunocompromised, chronically ill.Transmission: respiratory or skin with Transmission: respiratory or skin with hematogenous spread to CNShematogenous spread to CNSTrophozoite: 10-45Trophozoite: 10-45µm, spiny acanthopodia, µm, spiny acanthopodia, single nucleus, large central karyosomesingle nucleus, large central karyosomeCyst: 10-20µm, rounded, double walled (outer Cyst: 10-20µm, rounded, double walled (outer wall having a wrinkled appearance), single wall having a wrinkled appearance), single nucleus.nucleus.

Life cycleLife cycle

Consists of: Consists of: 1) trophozoite 2) cyst.1) trophozoite 2) cyst. resistant to resistant to dessication and mild dessication and mild chlorination.chlorination.Carried out by water Carried out by water and through the air.and through the air.

TRANSMISSION TRANSMISSION

PATHOGENESISPATHOGENESISGAE has an insidious onset.GAE has an insidious onset.CNS infection is acquired hematogenously by CNS infection is acquired hematogenously by the inhalation/aspiration of trophozoites and the inhalation/aspiration of trophozoites and cysts caused pneumonitis.cysts caused pneumonitis.Or through skin and mucosal ulceration.Or through skin and mucosal ulceration.Incubation period: questionable, may take weeks Incubation period: questionable, may take weeks to months to progress.to months to progress.Slow process of tissue invasion tends to Slow process of tissue invasion tends to stimulate granuloma formation.stimulate granuloma formation.Single or multiple focal lesions develop over a Single or multiple focal lesions develop over a prolonged period marking the chronic nature of prolonged period marking the chronic nature of the disease.the disease.Symptoms gradually develop: headache, fever, Symptoms gradually develop: headache, fever, fatigue, stiff neck, and altered mental status.fatigue, stiff neck, and altered mental status.

Granulomatous Amebic EncephalitisGranulomatous Amebic EncephalitisGAEGAE

portal of entry unknown, possibly respiratory tract, portal of entry unknown, possibly respiratory tract, eyes, skin eyes, skin presumed hematogenous dissemination to the presumed hematogenous dissemination to the CNS CNS infection associated with debility or infection associated with debility or immunosuppression immunosuppression onset is insidious with headache, personality onset is insidious with headache, personality changes, slight fever changes, slight fever progresses to coma and death in weeks to months progresses to coma and death in weeks to months amebas not yet detected in spinal fluid amebas not yet detected in spinal fluid

LABORATORY DIAGNOSISLABORATORY DIAGNOSISBy finding motile trophozoite in spinal fluid By finding motile trophozoite in spinal fluid specimen.specimen.By finding trophozoite and cyst form in:By finding trophozoite and cyst form in:

-brain biopsy tissue -brain biopsy tissue histological examination histological examination-scrapings from cutaneous or corneal lesions.-scrapings from cutaneous or corneal lesions.

Indirect immunofluorescent staining techniques.Indirect immunofluorescent staining techniques.Cultured on non-nutrient agar, overlaid with Cultured on non-nutrient agar, overlaid with viable viable E.coliE.coli bacteria bacteria stained with Giemsa or stained with Giemsa or calcofluor white calcofluor white identification of cyst or identification of cyst or trophozoite.trophozoite.

TREATMENT & PREVENTIONTREATMENT & PREVENTIONSulfamethazine; however, most cases are Sulfamethazine; however, most cases are only diagnosed at autopsy.only diagnosed at autopsy.no human cures documentedno human cures documentedSymptoms develop gradually over a Symptoms develop gradually over a prolonged period of time prolonged period of time the disease the disease may be overlooked.may be overlooked.

AMEBIC KERATITISAMEBIC KERATITIS predisposing factors predisposing factors – ocular trauma ocular trauma – contact lens (contaminated cleaning solutions) contact lens (contaminated cleaning solutions)

symptoms symptoms – ocular pain ocular pain – corneal lesions (refractory to usual treatments) corneal lesions (refractory to usual treatments)

diagnosis diagnosis – demonstration of amebas in corneal scrapings demonstration of amebas in corneal scrapings

treatment treatment – difficult, limited success difficult, limited success

corneal grafts often required corneal grafts often required