Lecture 11: Amoebae

unicellular

Amoebae are _______ microorganisms

protozoa

amoebae are ______

trophozoite and cyst

life cycle of amoebae?

trophozoite

actively motile feeding state

cyst

quiescent, resistant, infective

binary fission of trophozoite or development of trophozoites in multinucleated cysts

replication of amoebae

pseudopod formation

motility of amoebae by:

commensal

most amoebae are:

opportunistic

some amoebae are:

pathogenic

few amoebae are:

amebiasis

affects 10% of the worlds population and is associated with a significant number of deaths

colitis, diarrhea, dysentery, liver abscess, lung abscess

entamoeba histolytica disease

formed stool

cysts from entamoebae histolytic are typically in:

diarrheal stool

trophozoites from entamoeba histolytic are typically in:

ingestion of mature cysts (fecally contaminated food, water or hands)

how to get infected with entamoeba histolytic?

trophozoites remain in intestinal lumen -asymptomatic carriers

noninvasive infection of entamoeba histolytica

trophozoites invade the intestinal mucosa

intestinal disease of entamoebae histolytica

trophozoites invadeliver, brain, or lungs via bloodstream

extra intestinal disease of entamoeba histolytica

developing countries

the epidemiology of entamoebae histolytica is worldwide with higher incidence in:

amebiasis

entomoeba histolytica AKA

unsafe sexual practices

behavioral risk to get entamoeba histolytica

luminal amebiasis

from asymptomatic infection with E. histolytica

invasive intestinal amebiasis

dysentery, numerous bloody stools/day, colitis, appendicitis, toxic megacolon, amebomas

invasive extraintestinal amebiasis

liver abscess, peritonitis, pleuropulmonary abscess, cutaneous and genital amebic lesions

Microscopic ID of cysts and trophozoites in fresh or concentrated (cysts only!) stool, aspirates or biopsy material (colonoscopy, surgery)

diagnosis of amebiasis

entamoeba polecki

primarily parasite of pigs and monkeys, can cause mild diarrhea in humans

asymptomatic amebiasis infection treatment

asymptomatic amebiasis infection treatment

metronidazole or tinidazole, followed by iodoquinol, paromomycin

symptomatic intestinal disease or extraintestinal amebiasis treatment

ingestion of erythrocytes (E. hits. not commensal)

what is helpful in differentiation from non-pathogenic amebae?

acanthamoeba spp.

In soil, fresh, brackish, and sea water; sewage; swimming pools; contact lens equipment; medicinal pools; dental treatment units; dialysis machines; heating, ventilating, and air conditioning systems; vegetables, mammalian cell cultures, human tissues

cysts and trophozoites

acanthamoeba spp is only:

trophozoites

what are the infective forms of acanthamoeba spp?

eye, nose, damaged skin

how can entry of acanthamoeba spp. occur through?

severe keratitis

acanthamoeba spp. in the eye causes:

granulatomous amebic encephalitis (GAE), disseminated disease, skin lesions (in immunocompromised individuals)

respiratory system or through the skin with hematogenous dissemination with acanthomoeba spp.

free-living amoebae

acanthemoeba is a:

in tissue

where are cysts and trophozoites of acanthamoeba spp. found?

cysts, trophozoites, and flagellated forms

what are the three stages of Naegleria Fowler?

by promitosis (nuclear membrane remains intact)

how do trophozoites of naegleria fowleri replicate?

N. fowleri

found in fresh water, soil, thermal discharges of power plants, heated swimming pools, hydrotherapy and medicinal pools, aquariums, and sewage

primary amebic menigoencephalitis (PAM)

trophozoites of N. fowleri in the brain

in brain tissue

cysts from N. fowleri are NOT seen where?

free-living amoeba

N. Fowleri is a:

PAM of N. fowleri

Severe headache and other meningeal signs, fever, vomiting, and focalneurologic deficits, altered sense of smell

frequently coma and death within < 10 days

outcome of PAM?

GAE of acanthamoeba spp.

headaches, altered mental status, and focal neurologic deficits - death within several weeks

microscopic examination of CSF (wet mount may detect motiletrophozoites; Giemsa-stained smear - trophozoites with typical morphology)

diagnosis fo N. Fowleri

brain eating amoeba

PAM =

microscopic examination of stained smears of biopsy specimens (brain tissue, skin, cornea) or of corneal scrapings - trophozoites and cysts

acanthamoeba spp. diagnosis

Largely ineffective, some success with amphotericin B in combination with miconazole, rifampin - Prevention!

Largely ineffective, some success with amphotericin B in combination with miconazole, rifampin - Prevention!