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Diarrheas presenting +/- fever Flashcards

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1
Q

Shiga(Vero)-Toxin E. Coli (STEC) includes ??

FYI: Shiga toxin (Stx) = Verotoxin

A

EHEC: Enterohemorrhagic E. coli O157:H7 (the only sorbitol-negative STEC)

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2
Q

STEC/VTEC strains ???
causes ???
characterized by ??

A

O157:H7, O104:H4 (Germany), O26, O145
cause GI illness and HUS in young kiddos
hemolytic anemia, thrombocytopenia, acute renal failure (5-14% VTEC inf)

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3
Q

Plotkin’s EHEC scenario

A

petting zoo–>bloody diarrhea–>given abx–>exacerbated!–>needs dialysis bc of renal failure–>tonic clonic seizures–>HUS

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4
Q

HUS
can cause??
mostly in who ??

implicated strain ?? linked to ??
other strains ??

A

RBCs are destroyed, kidneys fail, thrombocytopenia
HTN, proteinuria, chronic renal failure, CNS symps
in 5% affected pts, mostly kiddos

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5
Q

ETEC agent

Stx is a ?? that binds ??

A

non-invasive E. coli, lysogenized by B-tox phage encoding a shiga toxin (Stx):
cytotoxin that binds globotriaosylceramide

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6
Q

VTEC cases in US: strains?

A

O157:H7 (known as EHEC)
also O111
>100 ww that cause HUS

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7
Q

German outbreak

A

O104:H4 in bean sprouts

new type of STEC: combo of EAEC and Stx production

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8
Q

EHEC reservoir/transmission

low or high dose org??

A

zoonosis beef and raw milk (cows eat contam. apples on ground)
low dose (50-500!) organism
person-person transmission happens!!
BUT mountain pk if educated, range (propagated) if poor personal hygiene

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9
Q

EHEC affects who ??

A

kiddos and oldies more affected

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10
Q

EHEC seasonality

risks

A

summer, risk for under grilled hamburgs

unpast. juices, milk, bean sprouts, poor personal hygiene

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11
Q

EHEC duration

but young kiddos may still poop org out for..

A

may resolve in 5-10 days

up to 2 weeks!

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12
Q

STEC/EHEC virulence factors

A 
pili: adherence
Shiga toxin (Stx) production
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13
Q

ingested EHEC adheres to ?? and then ??

A

colonic mucosa

produces Stx

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14
Q

main targets of Stx

A

gut, kidney, brain

–>produces HUS if gets into circulation (5-10% pts)

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15
Q

abx for STEC and EHEC and EAEC?

A

NO, associated with significantly higher risk for HUS development
–>release of bac cell-assoc. Stx and induces toxin gene expression (SOS response)

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16
Q

why can some EHEC strains cause HUS ??

A

able to adhere more tightly to intestinal mucosa

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17
Q

EAEC (Enteroaggregative E. coli) is a bad combo with

A

Stx–>high rate HUS in German outbreak
EAEC adhere avidly to intestine–>form biofilm
typically persistent diarrhea
human host adapted (vs. EHEC-zoonotic) so human fecal contamination

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18
Q

EHEC presentation

invasive?
fever?

A

diarrhea that becomes BLOODY 1-3 after onset
may have cramps, N/V
NONINVASIVE (unlike Shigella)
fever in less than 50%, only 1/3 have fecal leukocytes
commonly as AFEBRILE BLOODY DIARRHEA

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19
Q

EHEC dx

A

routine bac Cx on sorbitol-containing medium
assay for Shiga toxins (ID STEC)
Cx on MacConkey agar with sorbitol (not lactose)

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20
Q

EHEC on MacConkey agar

A

will be WHITE: sorbitol negative (other STECs and EAEC are sorbitol postitive-pink)

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21
Q

confirm EHEC dx with

A

serotyping (O157:H7)
ELISA for Stx in poop
PCR (alternative)

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22
Q

labs in HUS

A 
anemia
azotemia (N in blood)
dec. haptoglobin
elev. CRP, LDH, WBCs (leukocytosis), reticulocytes (mod)
hematuria/proteinuria  on UA
hemolysis on PBS: burr, helmets
neg. Coombs'
stool + for Stx (O157:H7)
thrombocytopenia: count
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23
Q

EHEC tx

Study These Flashcards
A

supportive tx ONLY

abx do not shorten course and may inc. risk for HUS

24
Q

if HUS happens and no Stx ??

Study These Flashcards
A

defect in alternative complement pathway

25
ddx HUS
``` acute abdomen acute gastroenteritis aapendicitis colitis DIC IBD intussucsception lupus TTP pancreatitis chemo agents: mitomycin, cisplatin, bleomycin, gemcitabine ```
26
entamoeba histolytica
invasive eukaryotic protozoan | trophozoite: lack mitochondria, anaerobe, needs large amounts of iron to survive
27
entamoeba ?? to in order to survive
ingest RBCs
28
ddx entamoeba from E. coli and E. hartmanni ddx entamoeba from E. dispar
nuclear morphology and/or size and presence of ingested RBCs electrophoretic isoenzyme patterns (zymodemes) as they are morphologically identical
29
entamoeba infectious form | survives where?
cyst can survive in moist soil or water >1 wk not killed by normal levels of chlorine
30
entamoeba can be killed by..
boiling, desiccation, light, heat, 200 ppm iodine
31
entamoeba occurs where? in who??
developing countries | US: immigrants, travelers, oral-anal sex
32
entamoeba reservoir low or high infectious dose?? transmitted how??
``` *only humans!* low infectious dose: 10^3 (average), 1 cyst can cause disease! fecal-oral rough food and water as vehicles oral-anal sex ```
33
entamoeba age, gender, seasonality assoc.
NONE
34
entamoeba risk factors
low SES travel to endemic areas closed populations promiscuitey
35
entamoeba is ingested as ?? reaches small bowel and ??? which travel to ?? and form ??
cyst excyst: release of eight amoebae travel to large bowel form mature cysts
36
entamoeba ??? adhere to colonic epithelium via this virulence factor
trophozoites | adhesins
37
entamoeba invade the epithelium via ?? and proceed ??
soluble cytotoxins: EC proteases that degrade elastase and collagen proceed laterally cell-to-cell
38
entamoeba: cell destruction occurs with formation of ?? surrounded by ?? (which implies what)
discrete ulcers "flasks" | normal appearing intestinal mucosa, suggesting little/no inflammation
39
entamoeba soluble cytotoxins also ?? which is responsible for the lack of inflammation and few WBCs in feces
kill PMNS on contact
40
entamoeba virulence factors that degrades C3a and C5a
cysteine protease
41
entamoeba vir factor: galactose-specific lectin
inhibits complement lysis at C8 and C9 assembly into MAC: Ag similarity btw adhesion and CD59 (human inhib. of assembly of comp. C8 and C9)
42
entamoeba vir fax: monocyte locomotion inhibition factor
inhibits monocyte migration and blocks respiratory burst of both macros and PMNs
43
entamoeba presentation | fever?
diffuse abd. pain, profuse bloody diarrhea (wide variation) | with or without fever
44
>75% have this if entamoeba inf left untx ??
liver abscess and colonic perforation
45
duration of entamoeba if left untx?
>3 wks | wl, abd pain
46
acute amoebic colitis fever?
bloody diarrhea, loose, intermittent, watery stool abd. pain RLQ, abd. tenderness, urgency to defecate 33% have fever and constitutional symptoms
47
fulminant colitis seen in who? | prevalence of entamoeba cases ?
uncommon presentation seen most in kiddos | 3-4%
48
ameboma (entamoeba) occurs in 1% of those with ?? | presents as a ?? and does not respond well to ??
intestinal disease mass lesion antiparasite therapy
49
extraintestinal amebiasis: amebic liver abscess organism ascends what vein?? present with ??
most common extraint. manifest ascends portal vein necrotic abscess, RUQ pain, fever, pleuritic pain
50
most frequent complication of amebic liver abscess (extraintestinal amebiasis) ??? via contiguous spread from right liver lobe to lung
pleuropulmonary amebiasis:
51
entamoeba dx RBCs? WBCs?
trophozoites or *cysts* in poop (3x samples, consecutive) RBCs present but few very few WBCs (mostly macros- PMS killed off)
52
more entamoeba dx
sigmoidoscopy : scraping or biopsy, take from edge of ulcer ELIXA for Ag PCR for DNA in stool liver scan - assoc. systemic leukocytosis
53
ddx entamoeba
IBD, Crohn's, anaeorobic parasites
54
entamoeba tx
metronidazole | newer/better: Tinidazole
55
entamoebe prevented by
improving sanitation | using condoms

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