Protozoa Flashcards
1
Q
Entamoeba histolytica
A
Key:
- colitis, diarrhea, abdominal pain, liver abcess
- flask-shaped ulcers
- *ingest RBCs
- anchovy paste
Extra:
- two forms: cysts- round, nonmotile, destruction resistant, transmissive form; trophozoites- pseudopod form, motile, mediating disease
- ingestion (fecal-oral or water-borne) -> exist in intestine -> invade forming “flask-shaped ulcers” (ingest RBCs) -> encysts in intestine -> cysts are shed in stool
2
Q
Giardia
A
Key:
- chronic diarrhea, bloating, flatus
- also has trophozoite (sucking disk & 4 flagella) and cyst form
- wild animals (beaver, racoon) - stream water
- homosexual men
Extra:
- most common enteric pathogen in U.S.
- fecal-oral, water-borne -> cysts -> stomach acid converts to trophozoite -> lumen attachment (sucking disk) -> encysts intestine -> shed in stool
3
Q
Cryptosporidium
A
Key:
- *AIDS chronic watery diarrhea, wasting
- low inoculation
- water borne transmission
- chlorine resistant
Extra:
- oocyst ingested -> excited sporozoites (banana-shaped, motile) attaches and enters intestinal epithelium -> trophozoite mutliplication inside vacuole -> transition to merozoites -> reinvade and continue cycle or release cysts in feces
4
Q
Toxoplasma gondii
A
Key:
- AIDS encephalitis (brain abcess)- reactivation
- aymptomatic mother -> neonate blindness, retardation, CNS
- cat poop
- raw meat, contaminated veg
Extra:
- primary disease - fever lymphadenopathy, self-limited (asymptomatic)
- reactivation- immunocompromised
- neonatal- primary pregnancy (asymptomatic), neonate asymptomatic sequelae (blindness, retardation, CNS)
- oocyst (cat poop) ingestion -> tachyzoite invasion (any cell) in vacuole [need IFN] -> tissue cyst containing organisms (quiescent)
5
Q
Malaria keys
A
- *RBC signet ring
- common in tropics, rare in U.S.
- periodic high fever, rigors
- coma/seizures (cerebral malaria)
- sever anemia, respiratory failure, kidney failure
- P. falciparum is most sever (cerebal malaria)
- immnity from recurrent infections wanes 1-2 yrs
- antigen variation evades immune system
- >10% RBCs infected -> poor prognosis
6
Q
Plasmodia falciparum features
A
- NOT dormant in liver, most severe
- banana-shaped gametocytes
- severe anemia, *cerebral malaria
- infects RBCs of all ages
7
Q
Plasmodia vivax & ovale features
A
- dormant in liver for months -> yrs (hypnozoite)
- infect only younger RBCs
- P. vivax requires Duffy antigen for invasion
8
Q
Plasmodia malariae features
A
- NOT dormant in liver
- infects only older RBCs
- mild/asymptomatic infection for yrs
9
Q
Chloroquine
A
- rarely useful due to resistance
- only active against erythrocyte stage, not liver
- Inhibits plasmodia heme polymerase, making FPP soluble and toxic
10
Q
Quinine
A
- only target RBC plasmodia (like chloroquine)
- same mechanism as chloroquine (given for chloroquine resistance)
- more toxic and less effective than chloroquine
- cinchonism
11
Q
Primaquine
A
- kills liver hypnozoites (P. ovale & P. vivax)
- not active against RBC form
12
Q
Malarone
A
- inhibits pyrimidine synthesis (blocks DHFR & ETC)
13
Q
Leshmania
A
Key:
- Visceral: fever, hepatosplenomegaly, cytopenia, darkened skin
- Cutaneous- excessive destruction
- tropical, desert sandfly
- macrophage with amastigote
- drug: stibogluconate
Extra:
- protozoa. two forms: amstigote- nonmotile w/i MNs. promastigote- motile, flagellated in sandlfy gut
- bite -> promastigote enters skin invading MNs -> amastogotes -> desiminates to reticuloendothelial organs -> replicates and lyses cell [cutaneous stops at dissemination]
14
Q
Mefloquine
A
- target RBC plasmodia
- *best drug for prophylaxis of chloroquine-resistant strains
15
Q
Pyrimethamine
A
- inhibits dihydrofolate reductase of plasmodia
- used in combination with treatment of chloroquine resistant strains
