GI 4 Flashcards
symptoms of bacillus cereus caused by food borne infection
diarrhea and abdominal pain
incubation and duration of bacillus cereus caused by food borne infection
incubation - 8 to 16 hours
duration - 12 to 24 hours
toxin in bacillus cereus caused by food borne infection and it mechanism
LT enterotoxin
vegetative growth in SI which activates adenyl cyclase therefore increasing cAMP
differences between bacillus cereus that causes food borne infection and food poisoning
food borne - longer incubation period at about 8-16 hours, LT enterotoxin, watery diarrhea due to LT protein
food poisoning - shorter incubation period within 4 hours, emetic toxin, vomiting caused by ST neurotoxin (emetic toxin), enterotoxin
1 parasitic cause of traveler’s diarrhea
giardia
situation that lead to infection by giardia
- poor sanitation
- travel to an endemic area
- recreational water
mechanism of giardia
ingestion of cysts –> trophozoite attach to SI–> replicate via binary fission and destroy brush border –> some mature to cyst
both cyst and trophozoite are passed in feces but trophozoite cannot survive the environment and cysts are the infective form
treatment of giardia
tinidazole - esp in those with chronic infection
what occurs if giardia is left untreated
most will resolve in 4 weeks while some will become a chronic infection
duration of cryptosporidium
self limiting and lasts about 10 days
type of diarrhea in endemic developing countries like tropics and subtropics for cryptosporidium
persistent diarrhea especially in children
what is cryptosporidium resistant to
chlorination and ozone
pathogenesis of cryptosporidium
ingestion of oocysts –> sporozoite –> trophozoite on the brush border of SI –> merozoite –> zygote which can either be released in stool as thin walled oocysts to go infect water or can sporulate and become thick walled oocysts and cause auto infection then go through the cycle again
what type of cryptosporidium stool is infective
fresh stool
treatment of cryptosporidium for immunocompromised like AIDs pts
supportive therapy
nitrazoanide
found in the tropics and subtropics but is less common and found in clusters
cyclospora cayetanensis
[compare to cryptosporidium which is also found in tropics and subtropics and causes persistent diarrhea in children
food that cyclospora cayetanesis was found in
cilantro in some clusters imported from Mexico (subtropic)
comparison of the oocysts found in stools of cryptosporidium and cyclospora cayetanensis
both use ziehl neelsen stain but cyclospora cayetanensis is bigger
treatment of cyclospora cayetanensis
trimethoprim-sulfamethoxazole
TMP-SMX
what is found in feces of those infected with cyclospora cayetenensis
unsporulated oocysts (as compared to thin walled sporulated oocysts excreted in those with cryptosporidium)
where do you find cystoisospora belli (aka isospora belli)
South America, Africa, Southeast Asia
rare in the US
where is the US do you find infections with cystiosospora belli aka isospora belli
- immunocompromised
- immigrants from Latin America
- Daycare Centers
- Psychiatric institutions
incubation and duration of cystiosospora belli aka isospora belli
incubation is 1 week
duration is 3 weeks
how do you diagnose cystiosospora belli aka isospora belli
oocysts found in wet mount and placed under autofluoresence (only one between cryptosporidium and cyclospora where the oocysts fluorescents)
treatment of cystiosospora belli aka isospora belli
trimethoprim-sulfamethoxazole
TMP-SMX (same as cyclospora)
pseudopod forming protozoa
entamoeba histolytica
outcomes of infection with entamoeba histolytic
- usually asymptomatic
- can lead to intestinal amoebiasis (dysentery which contains blood and mucus and amoebic diarrhea)
- abscesses in the liver
incubation and duration of entamoeba histolytica
incubation is days to weeks
duration is days to several months
diagnosis of entamoeba histolytica
- insensitive to O & P
- use PCR to differentiate the species
treatment of entamoeba histolytica
nitroimidazoles: metranidazole
infective form of entamoeba histolytica
cyst with 4 nuclei
features of rotavirus
- family of reoviridae
- naked ds RNA with 11 segments (6 structural and 5 non structural)
leading cause of diarrhea in hospital of children under the age of 5
rotavirus
what increases the incidence of rotavirus in developing and developed countries
developing - poor sanitation and unsafe drinking water
developed - poor sanitation
why are those who are less than 6 months and those greater than 5 not susceptible to infections by rotavirus
for those less than 6 months - protected by antibodies transferred to them from mother which declines by six months
those greater than 5 - they have built their own immunity to the virus due to previous infections
pathogenesis of rotavirus
primarily fecal oral route but could be water borne or air borne
incubation of rotavirus and shedding period of rotavirus
incubation is less than 48 hours
shedding may persist for 10 days or more but peaks at 8 days
histopathology and cause of diarrhea in rotavirus
after colonization of SI, rotavirus shorten and blunts the villi causing patchy, irregularly intact mucosa (EPEC does effacement of the microvilli)
as a result of the loss of the absorptive area, water moves across the damages surface causing diarrhea
complication of rotavirus and what other illness seems similar
- heavy diarrhea for up to 6 days and even longer
- dehydration which is severe and life threatening
- similar to vibrio cholera where the diarrhea was so much, it could lead to hypovolemic shock
how does one diagnose rotavirus
-peaks at 3/4 days in diarrhea so you use latex agglutination or EIA for characterization
what was the first rotavirus vaccine and why was it discontinue
Rotashield
-caused intussusception (dehydration in all patients as well)
how are the doses of Rotateq given and when was it approved
Feb 2006
-3 doses given between 6-32 weeks of age (not before 6 weeks and definitely not after 32 weeks)
Glaxo Smith Kline Rotarix is given in what doses and what type of vaccine is it
1st at 2 months and 2nd at 4 months
live, attenuated oral, G1P8
which serotypes of rotavirus does Rotateq work on
G1, G2, G3, G4, P8
