Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
47 Cards in this Set
- Front
- Back
What forms does E. histolytica exist as?
|
Trophozoite:
Fragile and cannot live outside the host One nucleus Cyst: Infective form Able to withstand the low pH of the stomach 4 nuclei |
|
How is E. Histolytica transmitted?
|
Ingestion of mature cysts in fecally contaminated food, water, or hands.
|
|
In pts with persistant infection of E. Histolytica, what is of immediate concern?
|
the trophozoite may invade the blood stream and reach extraintestinal tissues such as the liver. In the liver, they irreversably destroy hepatocytes and cause liver abscess.
|
|
36 y/o man presents with 10 days of bloody, mucus filled diarrhea. He just returned from india. PE shows fever, diffuse abd tenderness, and rectal exam was positive for blood. Stool antigen test was positive for amebic agent. Most likely agent? Txmt?
|
E. Histolytica
Metronidazole |
|
Where does exocystation occur in E. Histolytica? How does the trophozoite bind in the intestinal mucosa?
|
Small intestine
The trophozoite adhere to mucosal cells be lectin-binding receptors |
|
Amebic cytotoxins allow trophozoites of E. Histolytica to do what?
|
Invade the colon with lysis of epithelial cells and PMN's, which cause release of hydrolytic enzymes that damage the mucosa leading to amebic colitis and flask-shaped ulcers
|
|
Ulcer characterization in E. histolytica colitis
|
Flask-shaped
|
|
Produces an extracellular cysteine proteinase that degrades collagen and elastin
|
E. Histolytica
|
|
35 y/o male with AIDS presents with complaint of several weeks of watery diarrhea. He also complains of low grade fever, nausea, and anorexia. He has not been on his HAART. CBC shows increased WBC w/ neutrophil prominence. Acid-fast stool stain showed a protozoal infection. Most likely cause? Txmt?
|
Cryptosporidium parvum
Intravenous rehydration and restoration of HAART w/ paromomycin. In most other people, it is self-limited. |
|
Intracellular acid-fast coccidian protozoal agent
|
C. parvum
|
|
Site of infection in C. parvum. How does diarrhea develop?
|
Jejunum:
The sporozoites adhere to the absorptive int epithelial cells and focally disrupt the microvilli and envelop themselves in the host cell membranes via "intracellular but extracytoplasmic" process. Diarrhea develops when the intestinal absorption is impaired. |
|
Organism whose merozoites can undergo sexual reproduction within the same human host to regenerate oocysts, which are infective on excretion, thus permitting the direct and immediate fecal-oral transmission in men like John Hatenalas.
|
C. parvum
|
|
Organism whose pathogenesis includes invading the microvilli, where they complete their entire life cycle, and are found as "intracellular but extracytoplasmic" within host cell membranes.
|
C. parvum
|
|
3 y/o girl was brought to the ER following a 3-week hx of nausea, poor appetite, and abd pain. She had no bowel movements for 3 days. PE showed no fever, but abd was distended and tender. CBC showed normal WBC but eosinophil dominance. Abd X-rays show intestinal obstruction. Most likely organism? Txmt?
|
Ascaris lumbricoides
Mebenzadole |
|
If untreated, what may occur in Ascaris lumbricoides infection?
|
Intestinal obstruction and inflammation of mucosa may lead to bowel perforation, peritonitis, and sepsis.
|
|
Large intestinal nematode roundworm of humans. What form is infectious? How is it transmitted
|
Ascaris lumbricoides
The eggs are not infectious, rather its the larval form. Oral ingestion of fecally contaminated products containing eggs |
|
Most common method for diagnosing ascaris infection
|
eggs within the stool
|
|
Helminthic infections induce what inflammatory cellular responses
|
TH2 responses characterized by eosinophilia and IgE
|
|
Loeffler syndrome
|
Eosinophilic pneumonia caused by larval migration from intestinal mucosa, into the portal, then the systemic circulation, and finally to the lungs. Here the larvae mature for up to 2 weeks and penetrate the alveolar walls. From the alveoli, the ascend the bronchial tree and are swallowed. When they reach the small int, they develop into adults and live in the lumen.
|
|
Pathogenesis of ascaris lumbricoides
|
larval migration from intestinal mucosa, into the portal, then the systemic circulation, and finally to the lungs. Here the larvae mature for up to 2 weeks and penetrate the alveolar walls. From the alveoli, the ascend the bronchial tree and are swallowed. When they reach the small int, they develop into adults and live in the lumen.
|
|
49 y/o female presented with high fever, chills, jaundice, and upper abd pn. She is a recent immigrant from south america. One year before, she complained of pn in her R upper abd. She is a farmer who worked with sheepdogs. CBC is elevated. CT scan show a multi-loculated cyst with bile duct dilatation. Most likely organism? Txmt?
|
Echinococcus granulosus causing echinococcosis (hydatid cyst disease).
Surgerical removal of the parasitic mass. DOC is albendazole. |
|
Transmission of this organism is from fecal contact of sheepdogs, or canines, where it resides in the small bowel
|
Echinococcus granulosus
|
|
Organism that causes abscess within the liver and obstruction of the biliary duct, which results in jaundice and biliary duct dilation
|
Echinococcus granulosus
|
|
The adult female of Strongyloides stercoralis usually resides where?
|
Duodenum and jejunum
|
|
Uninfective larvae hatched from the eggs of a female S. stercoralis. Infective?
|
Rhabditiform larvae
Filariform larvae |
|
Organism who is able to penetrate intact skin
|
Strongyloides via filariform larvae
|
|
Organism that causes an urticarial, raised, erythematous rash, the most common dermatologic manifestation of parasitic infections
|
Strongyloides
|
|
Organism whose worms burrow into the mucosa and cause GI symtpoms such as abd pn, diarrhea, and in heavy infections, ulceration and sloughing of int mucosa
|
Strongyloides
|
|
42 y/o male presents with 3 weeks of worsening diarrhea, abd pn, and fevers. He also complains of an itchy rash over his buttocks and groin area. CBC shows eosinophilic dominance. Most likely organism? Txmt?
|
S. stercoralis
Ivermectin |
|
Katayema fever is associated with?
|
Acute Schistomiasis:
4-6 wks after infection, at the time of egg release. Fever, cough, abd pn, diarrhea, eosinophilia, and hepatosplenomegaly. |
|
Diagnosis of this parasite is via eggs in the urine. Where does in live?
|
S. haematobium:
lives in the venous plexus near the urinary bladder and ureters. |
|
Niche of S. mansoni and japonicum
|
Inferior mesenteric vein
Superior mesenteric vein of both the large and small intestines |
|
Intermediate host of schistomiasis
|
snails
|
|
Transmission of schistomiasis to humans
|
Penetration of intact skin with infective cercariae, which are released from infected snails. Once within, the human host they shed their tail and become schistosomulae, where they migrate through tissues and take up residence within veins.
|
|
Life cycle of S mansoni begins with?
|
eggs shed within feces of a pt. These eggs then hatch and release miracidia which swim and infect snails, which produce cercariae
|
|
Form of s. mansoni that infect snails
|
miracidia
|
|
Most diagnostic method for identifying schistosomiasis
|
eggs in the stool
|
|
Chronic schistosomiasis is due to?
|
Immunolgic rxns of to schistosoma eggs trapped in tissues. Including IgE, eosinophilia, via activation of TH2 cells that are the main pathogenic element.
|
|
Organism that causes a TH2 response that leads to profound granulomatous rxn resulting in portal hypertension with hematemesis, and hepatosplenomegaly, with collagen deposition and fibrosis within the hepatocytes.
|
Schistosomiasis:
Ultimately leads to cirrhosis |
|
DOC in txmt of schistosomiasis
|
Praziquantel
|
|
25 y/o male presents with 2 week hx of diarrhea, nausea, flatulence and lack of appetite after backpacking in the Rocky mountains. Diarrhea was initially watery, but now greasy and foul. He now feels bloated. He has had no fever or chills. Duodenal biposy shows an intestinal pear shaped flagellate protozoa. Organism? Transmission?Txmt?
|
Giardia Lamblia
Fecally contaminated water Metronidazole |
|
How many pairs of flagella does G. lamblia have?
|
4
|
|
G. Lamblia exists in what forms?
|
Trophozoite:
pathogenic form Cyst: Infective Survives the pH of the stomach |
|
How may cysts be detected in diagnosis of G. Lamblia
|
Using a direct mount of feces. Trophozoites may be seen in a duodenal biopsy if 3 consecutive fecal tests are negative.
|
|
Produces an IgA protease that allows for adherence to the organism
|
G lamblia
|
|
Organism that initiates infection by being taken up by macrophages in peyer patches. From here a T cell mediated inflammatory response leads to crypt hyperplasia and microvilli injury in the brush border, resulting in watery and then greasy, foul stools.
|
G lamblia
|
|
Mechanism of malabsorption diarrhea in G. Lamblia
|
Trophozoites lead to disruption of the microvilli of the brush border, causing villi atrophy (via proteinase or lectin-binding protein).
|