Toxoplasmosis: Amoebic Meningitis Flashcards by Iseoluwa Ojo

Aetiology:

Toxoplasma gondii - A _______ _______

usually (asymptomatic or symptomatic?) infection in humans

tissue sporozoan

asymptomatic

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Toxoplasmosis

Significant disease in _____________________,__________ patients and occasionally in ____________ individuals.

congenitally infected infants, immunodeficient

immunocompetent

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Epidemiology of toxoplasmosis

T. gondii infection is a worldwide ______.

The organism infects ______,_______ and _________ animals, including ______.

zoonosis

herbivorous, omnivorous, and carnivorous

birds

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Epidemiology of Toxoplasmosis

Mode of transmission:

Infection in humans most commonly occurs through
•the ________ of _______________ that contains _______

•the ________ of _________ contaminated with _______

•____________(________) transmission from a mother who acquired her infection during gestation

ingestion of raw or undercooked meat

tissue cysts

ingestion of water or food ; oocysts

transplacental (congenital)

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Epidemiology of Toxoplasmosis

Less common transmission are:
– by _______ of _____________
–____________ of ___________
–___________ with contaminated needles
-exposing _________ or _____ surfaces to the parasite

transplantation of an infected organ

transfusion of contaminated blood cells.

Needle stick injury

open lesions or mucosal

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Toxoplasmosis

The normal final hosts are strictly _____ and members of the family ______.

They play a significant role as powerful ______ of the infection in nature because the ______-producing (sexual or asexual?) stage of Toxoplasma develops in their ________.

cats; Felidae

amplifiers

oocyst; sexual

intestine

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Life cycle of Toxoplasmosis

Organisms (either ________ from ________ or ________ from ________ cysts) invade the ________ cells of the ____________________, where they form ________ or ________________

After sexual fusion of the gametes, ________ develop, exit from the ________ into the ________ of the cat, and pass out via the ________.

In about __________, the environmentally (sensitive or resistant?) ______ are infective

When _______ are ingested by the cat, the parasites _______________. If oocysts are ingested by intermediate hosts such as certain birds, rodents, or mammals, including _______, the parasites can ____________ but reproduce only _________.

sporozoites ; oocysts

bradyzoites ; tissue

mucosal cells ;cat’s small intestine

schizonts ; gametocytes.

oocysts ;host cell

gut lumen ; the feces

48 hours; resistant ; oocysts

Oocysts; repeat their asexual and sexual cycle

humans; establish an infection

asexually.

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Only members of the ____ family shed oocysts

cat

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Life cycle of Toxoplasmosis

The oocyst opens in the human’s or animal’s ________ and releases the _______, which pass through the ______, circulate in the body, and invade various cells, especially _________, where they form ____________.

________ multiply, break out, and spread the infection to ________ and other organs.

duodenum ; sporozoites

gut wall; macrophages; trophozoites

Trophozoites ; lymph nodes

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Trophozoites of toxoplasmosis

_________ are the actively proliferating trophozoites, which are observed during the (acute or chronic?) stage of infection

Tachyzoites

Acute

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Life cycle of toxoplasmosis

The trophozites (rapidly multiplying _________ cells called ________ ) initiate the (acute or chronic?) stage of disease.

Subsequently, they penetrate _____ cells, especially of the _____ and _______, where they multiply (slowly or rapidly?) (as ______) to form ________ ——- cysts, initiating the (acute or chronic?) stage of disease.

The tissue cysts are infective when _________ (resulting in the intestinal ______ stage and _______ production); when they are eaten by other animals, more _________ are produced (_______).

crescentic ;tachyzoites

acute ; nerve

brain and eye

slowly ;bradyzoites

quiescent tissue ; chronic

ingested by cats ; sexual ; oocyst production

tissue cysts ;asexually

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Tissue cysts of toxoplasmosis are found most commonly in the _____ and in __________________________ muscle but can occur in ______ organ

brain

skeletal and cardiac muscle

any organ

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Pathogenesis of Toxoplasmosis 1

The tachyzoite directly ________ and has a predilection for ________ cells and those of the _______________ system.

Humans are relatively (resistant or sensitive?) , but a (low or high?) -grade _______ infection resembling _____________ may occur.

When a _______ ruptures, releasing numerous _______, a local _______ may cause _______, _______ of blood vessels, and cell death near the ___________.

destroys cells ;parenchymal cells

reticuloendothelial system ; resistant

low; lymph node

infectious mononucleosis

tissue cyst ; bradyzoites

hypersensitivity reaction ; inflammation

blockage; damaged cyst.

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Pathogenesis Of toxoplasmosis 2

Presence of ________ is the hallmark of active infection

They reside and multiply within ______ in their host’s cells, can infect virtually all __________ and _________ cell types, and multiply approximately every ______ to form __________.

Continuous multiplication leads to cell disruption and release of organisms that go on to invade nearby cells or are transported to other areas of the body by _______ and _______.

Tachyzoites; vacuoles

phagocytic and nonphagocytic cell types

6 to 8 hours ; rosettes.

blood and lymph.

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Tachyzoites appear to (actively or passively?) and (slowly or rapidly?) migrate across epithelial cells and may traffic to distant sites while ____cellular.

Actively ; rapidly

extra

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Pathogenesis Of Toxoplasmosis 3

T. gondii multiplies ______cellularly at the site of invasion (the _________ is the major route for and the initial site of infection in nature)

________ released from tissue cysts or ______ released from oocysts penetrate, differentiate to _______, rapidly multiply within __________ cells.

Organisms may spread first to the ______ lymph nodes and then to distant organs by invasion of ________ and _______

T. gondii tachyzoites infect virtually all cell types, and cell invasion occurs as a/an (active or passive?) process.

intra; gastrointestinal tract

bradyzoites ;sporozoites

tachyzoites; intestinal epithelial

mesenteric ; lymphatics and blood.

active

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Pathogenesis Of Toxoplasmosis 4

Survival of tachyzoite is due to the formation of a ____________ that lacks _______ necessary for ______________

Active invasion of ______ by ______ does not trigger ________ mechanisms.

With the appearance of humoral and cellular immunity, only those parasites protected by ________ habitat or within ________ shall survive.

An effective immune response significantly reduces the number of _________ in ____ tissues

after the initial acute stages, _________ are (often or rarely?) demonstrable histologically in tissues of infected immunocompetent humans.

parasitophorous vacuole

host proteins ; fusion with lysosomes

macrophages ; tachyzoites

oxidative killing; intracellular habitat

tissue cysts; tachyzoites ; all

tachyzoites ; rarely

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Clinical Features of Humans toxoplasmosis:

(Asymptomatic or Symptomatic?) in most immunocompetent humans

Congenital infection develops only when ___________ mothers are infected during pregnancy, is usually of (little or great?) severity

postnatal toxoplasmosis is usually much (more or less?) severe

Asymptomatic

nonimmune; great

Less

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Clinical Features of Humans toxoplasmosis:

fulminating fatal infections may develop in patients with ______, presumably by alteration of a _____ infection to an ______ one.

Varying degrees of disease may occur in immunosuppressed individuals, resulting in _________ or ________ , _______ ,___________ , or various other conditions.

AIDS; chronic ; acute

retinitis or chorioretinitis

encephalitis, pneumonitis

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Clinical features of toxoplasmosis

The major features of (acute or chronic ?) acquired _______ toxoplasmosis are those of meningoencephalitis, myocarditis, pneumonitis, lymphadenitis, rash, and occasionally ______

In rare instances in immunocompromised hosts ,———— may be a prominent clinical manifestation resembling _________

Marked ______,__________,_________, and __________s occur in such patients.

acute; disseminated ; hepatitis

polymyositis ; autoimmune polymyositis.

Marked myalgias, muscle weakness and swelling, and fasciculations

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Clinical features of toxoplasmosis

Muscle biopsy specimens show ______ with destruction of muscle fibers, and _________ of Toxoplasma gondii can be found in areas of muscle that are __________

interstitial myositis

pseudocysts

free of inflammatory reaction

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Clinical features of Toxoplasmosis

Congenital infection leads to ________, _________, _________ calcifications, _______ disturbances, and _________ or ________

Major cause of _______ and other congenital defects.

Infection during the first trimester generally results in _________ or ________

Second- and third-trimester infections induce (more or less?) severe ______ damage

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stillbirths, chorioretinitis

intracerebral; psychomotor

hydrocephaly or microcephaly

stillbirth or major CNS anomalies.

Less; neurologic

Clinical features of Toxoplasmosis

Clinical manifestations of these infections may be delayed until _____, even beyond ______.

_______ problems or ______ difficulties may be caused by the long-delayed effects of late prenatal toxoplasmosis.

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long after birth

childhood

Neurologic; learning

Diagnosis of Toxoplasmosis
Direct detection of the organism is by
– ___________ assay,
– histopathology with immunoperoxidase staining,
-__________
–______ inoculation.

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polymerase chain reaction (PCR)

tissue culture

mouse

Diagnosis of Toxoplasmosis Serologic assays can help distinguish ______ from _______ infection and can identify patients at risk for __________ .

acute from chronic reactivation

Treatment of toxoplasmosis Immunocompetent asymptomatic patients:____- Immunocompromised patients: The therapy: ____________ plus ____________ plus ____________ OR ____________ plus ____________ plus either ____________ or ____________ OR ____________ ____________

no therapy pyrimethamine plus sulfadiazine plus leucovorin Pyrimethamine plus leucovorin plus either clindamycin or atovaquone Trimethoprim sulfamethoxazole

Treatment of Toxoplasmosis ______ are given only for clinically significant edema or mass effect, and _______ are given only after a seizure.

Corticosteroids anticonvulsants

Treatment of Toxoplasmosis In pregnancy less than 18 weeks: _______ Greater than 18weeks: ________+ ________ Congenital infection: ___________

spiramycin pyremethamine + Folinic acid pyremethamine

Prevention of Toxoplasmosis Avoidance of contact with _______ particularly for pregnant women with negative serologic tests. pregnant women should avoid all contact with _____, particularly _____ daily changing of ______ and its safe disposal, since oocysts usually take ______ to become infective,

cat feces cats; kittens cat litter; 48 hours

Prevention of Toxoplasmosis Meat should be cooked very well to kill _______ Freezing meat at _____°C for ____ hours or heating to ___°C for _____ minutes will kill the organism.

tissue cysts −20; 48hrs 50; 4-6mins

Prevention of Toxoplasmosis Kitchen cleanliness, ______ after touching raw meat . Periodic serologic screening for ____________ antibodies to Toxoplasma is recommended. Do not allow cats to eat __________ and ________ Wash hands thoroughly after outdoor activities

handwashing immunoglobulin (Ig) G and IgM wild rodents and birds

prophylaxis of Toxoplasmosis Immunocompromised patients: –_____-_____ –_______ + _______

TMP-SMX dapsone; pyrimethamine

Free-living amebae (FLAs) are (aerobic or anaerobic?) , __karyotic ____ that comprise several genera.

Aerobic eukaryotic protists

Free-living amebae (FLAs) have ____ known insect vectors Have ____ human carrier states of epidemiologic importance,

No No

Free-living amebae (FLAs) (Little or Major?) relationship between poor sanitation and their transmission Infection of humans with FLAs is an (frequent or infrequent?) but often _____ occurrence in both normal and immunocompromised individuals.

Little ; infrequent fatal

Free-living amebae (FLAs) Central nervous system (CNS) invasion by __________,_________,__________ has been reported in hundreds of patients worldwide, with thousands of ____________________ cases described.

Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris Acanthamoeba keratitis

Four distinct clinical syndromes are caused by the FLAs that infect humans •_________________________(PAM) •_____________________(GAE) •_________________ disease •______________ (AK).

primary amebic meningoencephalitis (PAM) •granulomatous amebic encephalitis (GAE) •disseminated granulomatous amebic disease •Amebic keratitis (AK).

Microbiology and Epidemiology of Free-living amoeba The trophozoite stages of these organisms feed on _______ and ___________ Naegleria fowleri is widely distributed globally and has been isolated from _______, most commonly in (warm or cold?) environments.

bacteria and debris in the environment. fresh water; warm

Microbiology and Epidemiology of Free-living Amoeba Acanthamoeba spp. are ubiquitous members of the environment and are found worldwide in ______ and ________. Balamuthia mandrillaris is widely distributed and has been isolated from ____

soil and fresh water soil.

Clinical Manifestations and Diagnosis N. fowleri typically causes a __________ ————- in healthy, immunocompetent young patients, in association with ______ in _______ water.

fulminant meningoencephalitis swimming; warm fresh

N. fowleri The disease is nearly always fatal. T/F

Clinical Manifestations and Diagnosis N. fowleri The cerebrospinal fluid (CSF) profile of patients with N. fowleri primary amebic meningoencephalitis (PAM) is similar to that seen in ______ meningitis (____ white blood cell count, ____ glucose, ___ protein), but with a ____ Gram stain and culture. (Motile or Non-motile?) trophozoites can sometimes be seen on wet mount of the CSF.

bacterial; high Low; high ; negative Motile

Clinical Manifestations and Diagnosis Neuroimaging studies in patients with PAM are usually (specific or nonspecific?).

nonspecific.

Clinical Manifestations and Diagnosis Acanthamoeba spp. and B. mandrillaris cause the ______ onset of focal neurologic deficits mental status changes (_______________) are related to central nervous system ___________.

subacute granulomatous amebic encephalitis [GAE] mass lesions

Clinical Manifestations and Diagnosis Acanthamoeba is mostly seen in _________ and _________ individuals Balamuthia occurs in _____________________ patients. The case-fatality rate for these infections is also (low or high?).

immunocompromised and debilitated both immunocompromised and immunocompetent High

Clinical Manifestations and Diagnosis CSF studies of patients with GAE are usually (specific or nonspecific?) , and it is (common or rare ?) to isolate organisms from the CSF. Neuroimaging studies generally reveal multiple _________ lesions in the brain, with or without contrast enhancement. Biopsy of involved tissues (skin, brain, etc.) can be diagnostic, usually via histopathologic examination/immunohistochemical staining or polymerase chain reaction (PCR).

nonspecific; rare space-occupying

Clinical Manifestations and Diagnosis Acanthamoeba spp. and B. mandrillaris can involve other sites ( _____,_______,_______, and skin). Acanthamoeba spp. also cause _____ threatening ______ in otherwise healthy individuals in association with ______ use.

lungs, sinuses, adrenals sight; keratitis; contact lens

Diagnosis of free living amoeba Diagnosis depends on a __________, in conjunction with IN VIVO ____ microscopy Demonstration of Acanthamoeba in _____________ biopsy specimens by histopathologic examination, culture, or PCR.

high clinical suspicion confocal corneal scrapings

Therapy for FLA Therapeutic regimens for free-living amebic infections of humans are well defined T/F

F not well defined.

Therapy for FLA Treatment for N. fowleri PAM should include high-dose ______ amphotericin products; _______ amphotericin may also provide some benefit, and the addition of azoles, rifampin, miltefosine, or other antimicrobials should be considered. Acanthamoeba keratitis should be treated with _______ _______ or ———- ———— adjunctive surgical therapy may also be necessary.

intravenous; intrathecal topical chlorhexidine or polyhexamethylene biguanide

Acanthamoeba GAE should be treated with ___________ regimens, possibly including ______,_______,________,_______, and ______. However, the most efficacious regimen is _________________

Combination antimicrobial pentamidine, an azole, a sulfonamide, miltefosine, and flucytosine not currently known.

B. mandrillaris GAE should be treated with ________ regimens, possibly including pentamidine, flucytosine, a sulfonamide, albendazole, an azole, a macrolide, amphotericin, and/or miltefosine. However, the most efficacious regimen is _______________

combination antimicrobial not currently known.

_________________ may play an adjunctive role in the management of both forms of GAE( __________ and __________)

Surgical débridement Acanthamoeba GAE B. mandrillaris GAE

Toxoplasmosis: Amoebic Meningitis Flashcards

(53 cards)