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Micro > Diarrheas presenting +/- fever > Flashcards

Diarrheas presenting +/- fever Flashcards

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

A

supportive tx ONLY

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

24
Q

if HUS happens and no Stx ??

A

defect in alternative complement pathway

25
Q

ddx HUS

A 
acute abdomen
acute gastroenteritis
aapendicitis
colitis
DIC
IBD
intussucsception
lupus
TTP
pancreatitis
chemo agents: mitomycin, cisplatin, bleomycin, gemcitabine
26
Q

entamoeba histolytica

A

invasive eukaryotic protozoan

trophozoite: lack mitochondria, anaerobe, needs large amounts of iron to survive

27
Q

entamoeba ?? to in order to survive

A

ingest RBCs

28
Q

ddx entamoeba from E. coli and E. hartmanni

ddx entamoeba from E. dispar

A

nuclear morphology and/or size and presence of ingested RBCs

electrophoretic isoenzyme patterns (zymodemes) as they are morphologically identical

29
Q

entamoeba infectious form

survives where?

A

cyst
can survive in moist soil or water >1 wk
not killed by normal levels of chlorine

30
Q

entamoeba can be killed by..

A

boiling, desiccation, light, heat, 200 ppm iodine

31
Q

entamoeba occurs where? in who??

A

developing countries

US: immigrants, travelers, oral-anal sex

32
Q

entamoeba reservoir
low or high infectious dose??

transmitted how??

A 
*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
Q

entamoeba age, gender, seasonality assoc.

A

NONE

34
Q

entamoeba risk factors

A

low SES
travel to endemic areas
closed populations
promiscuitey

35
Q

entamoeba is ingested as ??
reaches small bowel and ???
which travel to ??
and form ??

A

cyst
excyst: release of eight amoebae
travel to large bowel
form mature cysts

36
Q

entamoeba ??? adhere to colonic epithelium via this virulence factor

A

trophozoites

adhesins

37
Q

entamoeba invade the epithelium via ?? and proceed ??

A

soluble cytotoxins: EC proteases that degrade elastase and collagen
proceed laterally cell-to-cell

38
Q

entamoeba: cell destruction occurs with formation of ?? surrounded by ?? (which implies what)

A

discrete ulcers “flasks”

normal appearing intestinal mucosa, suggesting little/no inflammation

39
Q

entamoeba soluble cytotoxins also ?? which is responsible for the lack of inflammation and few WBCs in feces

A

kill PMNS on contact

40
Q

entamoeba virulence factors that degrades C3a and C5a

A

cysteine protease

41
Q

entamoeba vir factor: galactose-specific lectin

A

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
Q

entamoeba vir fax: monocyte locomotion inhibition factor

A

inhibits monocyte migration and blocks respiratory burst of both macros and PMNs

43
Q

entamoeba presentation

fever?

A

diffuse abd. pain, profuse bloody diarrhea (wide variation)

with or without fever

44
Q

> 75% have this if entamoeba inf left untx ??

A

liver abscess and colonic perforation

45
Q

duration of entamoeba if left untx?

A

> 3 wks

wl, abd pain

46
Q

acute amoebic colitis

fever?

A

bloody diarrhea, loose, intermittent, watery stool
abd. pain RLQ, abd. tenderness, urgency to defecate

33% have fever and constitutional symptoms

47
Q

fulminant colitis seen in who?

prevalence of entamoeba cases ?

A

uncommon presentation seen most in kiddos

3-4%

48
Q

ameboma (entamoeba) occurs in 1% of those with ??

presents as a ?? and does not respond well to ??

A

intestinal disease
mass lesion
antiparasite therapy

49
Q

extraintestinal amebiasis: amebic liver abscess
organism ascends what vein??
present with ??

A

most common extraint. manifest
ascends portal vein
necrotic abscess, RUQ pain, fever, pleuritic pain

50
Q

most frequent complication of amebic liver abscess (extraintestinal amebiasis) ???
via contiguous spread from right liver lobe to lung

A

pleuropulmonary amebiasis:

51
Q

entamoeba dx
RBCs?
WBCs?

A

trophozoites or cysts in poop (3x samples, consecutive)
RBCs present but few
very few WBCs (mostly macros- PMS killed off)

52
Q

more entamoeba dx

A

sigmoidoscopy : scraping or biopsy, take from edge of ulcer
ELIXA for Ag
PCR for DNA in stool
liver scan - assoc. systemic leukocytosis

53
Q

ddx entamoeba

A

IBD, Crohn’s, anaeorobic parasites

54
Q

entamoeba tx

A

metronidazole

newer/better: Tinidazole

55
Q

entamoebe prevented by

A

improving sanitation

using condoms

Micro (61 decks)

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