GI/GU Protozoans

Question 1

describe the transmission and life cycle of entamoeba histolytica

Answer 1

1. mature cyst is ingested
2. de-cyst in intestin, yeilding trophozoites
3. trophozoites can colonize colon, feeding via phagocytosis; multiply via binary fission
   
   • can invade intestinal/liver tissues
   • make more cysts passed in feces

Question 2

unique histology of entamoeba histolytica

Answer 2

flask shaped infection

invades into submucosa; can go further in some cases

Question 3

manifestation of entamoeba histolytica infection

Answer 3

intestinal disease ranging from asymptomatic colonization to colitis, megacolon, hemorrhage, fistulas

amebic liver abscess can cause fever, RUQ tenderness, hepatomegaly; can rupture and spread

Question 4

pathology of entamoeba histolytica

(how do these bugs cause disease)

Answer 4

amoebas adhere to epithelial cells(gal/galnec lectin)

cysteine proteases degrade ECM

amebapores form pores in target cell

killed cells are EATEN; nomnomnomnom

Question 5

diagnosis of entamoeba histolytica

Answer 5

1. intestinal: stool antigen, PCR assay
2. liver abscess: ultrasound, CT, CXR(elevated diaphragm from large liver), needle aspirate

Question 6

treatment for entamoeba histolytica

asymptomatic

invasive

Answer 6

1. asymptomatic: diloxanide furoate, paromomycin, iodoquinol
2. invasive: metronidazole + luminal amebicide

Question 7

invasive and noninvasive entamoeba species

Answer 7

invasive = e. histolytica

noninvasive = e. dispar

Question 8

describe transmission and life cycle of giardia intestinalis

Answer 8

fecal-oral transmission of cysts(very resilient even in cold water)

cyst develops into infective trophozoite which attach to upper small intestine

Question 9

pathology of giardia

Answer 9

trophozoites localize in upper small bowel

dont invade; attch via ventral sucker to brush border

induce mucosal inflammation, induce apoptosis, prevent absorption, disrupt tight jxns

Question 10

clinical manifestation of giardia

Answer 10

malodorous watery diarrhea/flatulence

ab cramps, bloating, fatigue

low-grade fever

usually lasts > 2 wks

Question 11

treatment for giardia

Answer 11

metronidazole, tinidazole

Question 12

chronic, debilitating, life-threatening diarrhea in AIDS persons

frequent cause of recreational water outbreaks

intracellular

Answer 12

cryptosporidium (hominis and parvum)

Question 13

transmission and life cycle of cryptosporidium spp.

Answer 13

fecal-oral transmisison or food/water

1. oocyst enters mouth
2. sporozoites released in small bowel
3. mature into trophozoite IN brush border
4. sexual cycle results in oocysts which pass in feces again

Question 14

cryptosporidium disease

differentiate immunocompetent vs immunocompromised host

Answer 14

general: watery diarrhea, ab cramps, nausea, fever, malaise, wt. loss

compromised: voluminous watery diarrhea; marked weight loss; cant resolve spontaneously

competent: symptoms resolve after 5-12 days;

Question 15

treatment for cryptosporidium

Answer 15

supportive therapy

immunocompetent: nitazoxanide

immunocompromised: reverse immune suppression, not many effective drugs for AIDS pts….

Question 16

most common non-viral STD

Answer 16

trichomonas vaginalis

10-50% of sexually active women

Question 17

manifestation of trichomonas vaginalis

women

men

Answer 17

Women

1. dmg via direct contact = microulcerations
2. vaginal discharge
3. dysuria
4. pregos can have low wt babies or preterm deliver

Men

usually asymptomatic; can have discharge;

complications: prostatitis, epididymitis, urethral sricture, infertility

Question 18

diagnosis of trichomonas vaginalis

Answer 18

ID organism via wet mount or culture

Question 19

treament for trichomonis vaginalis

Answer 19

metro/tinidazole

Question 20

treatment for cyclospora

Answer 20

TMP-SMX

immunocompetent can prolly recover w/out treatment

Question 21

diagnosis of cyclospora

Answer 21

multiple stool samples(at least 3)

find oocysts in stool; can use acid fast as well

Question 22

clinical symptoms of cyclospora

Answer 22

sudden onset

fever, abdominal cramping

frequent watery diarrhea

can last several weeks if untreated

Question 23

transmission/life cycle of cyclospora

Answer 23

fecal-oral; contaminated food/water

oocysts(each containing 2 sporozoites) are ingested

sporozoites infect epithelial cells of upper small intestine