Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Bacte LEC > Escherichia > Flashcards

Escherichia Flashcards

1
Q

Colon bacillus

A

E coli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

E Coli

Previously considered as a harmless member of the colon biota

• First described by______
• Associated with wide range of clinical syndromes
• Primary marker of___ in water

A

Theodore Escherich in 1885

fecal contamination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

• Closely related to Shigella in terms of DNA homology but can be easily
differentiated through______

• E. coli is____ fermenter
• Shigella is_____ fermenter

A

lactose fermentation:

lactose

non-lactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Escherichia coli (Colon bacillus)
Characteristics

• Motile, possess an adhesive
fimbriae and sex pili
• Has _____antigens

A

O, H and K

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Escherichia coli (Colon bacillus)
General laboratory findings
Fermenter of: (4)

A

Glucose, lactose, trehalose and xylose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Associated with diarrhea of infants (major cause!) and adults in tropical and subtropical areas

Acquired via ingestion of contaminated food and water

A

ETEC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Most common cause of diarrheal disease commonly referred
as TRAVELLER’S DIARRHEA/TOURIST’S,
DIARRHEA/ “MUNTEZUMA’S REVENGE”

A

ETEC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

10^6 - 10^10 (1000000 - 10000000000) organisms is the infective dose of organisms in immunocompetent individuals.

A

Enterotoxigenic E.coli (ETEC)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

• Serves as a protective mechanism against colonization and disease initiation

• Patients suffering from_____ - higher risk compared to normal persons

A

ETEC

Stomach acidity

achlorhydria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Colonization of ETEC in the small intestine mediated by fimbriae
Releases toxins in the small intestine

A

• Heat - Labile (LT) toxin

• Heat - stable (ST) toxin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Enterotoxigenic E.coli (ETEC)
Pathophysiology

  • consists of 2 subunits, one A subunit and five B subunit.

B subunit binds to the GM, ganglioside receptor, the same receptor used by cholera toxin to bind on the epithelial cells in the small intestine.

The whole toxin is endocytosed by the epithelial cells of the intestine

A

LT toxin (heat labile)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Pathophysiology
The increased levels of CAMP stimulate the intestinal cells to hyper secret fluids and electrolytes into the lumen of the intestine.

This results in watery diarrhea (similar to cholera).

A

Enterotoxigenic E.coli (ETEC)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Enterotoxigenic E.coli (ETEC)
Pathophysiology

• Binds to the transmembrane guanylate peptide cyclase receptor found on the surface of the intestine.
• Binding results in an increased accumulation of cyclic guanosine monophsophate (cGMP) which also causes hyper-secretion of fluid and electrolytes.
• This results in watery diarrhea

A

Heat - stable (ST) toxin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Diagnosis
Characteristic symptoms such as watery diarrhea, abdominal cramps, and nausea

Isolation of lactose fermenting organisms on selective and differential media

Biochemical tests
Multiplex PCR

A

Enterotoxigenic E.coli (ETEC)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Note: The presence of colonies on EMB that exhibit a “green
metallic sheen” does not definitively indicate that presence of
Escherichia coli since some (2)
species are also able to produce the same type of colony
characteristic on EMB

A

Citrobacter and Enterobacter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Associated with dysentery (watery diarrhea with blood, leukocytes, and mucus) similar to Shigella spp.

Occur in adults and children

Direct person-to-person transmission via fecal oral route

Clinical infection characterized by: fever, sever abdominal cramps, malaise, and watery diarrhea.

A

Enteroinvasive E.coli (ElEC)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Pathophysiology
• Plasmid mediated bacterial invasion (pinv genes) mediate the colonization of
EIC into the colonic epithelium

•____ lyses phagocytic vacuole and replicate into the cell cytoplasm

• Movement within the cytoplasm and into the adjacent cells is regulated by formation of actin filaments

• This destroys colonic epithelium cells and results in inflammation that could progress to colonic ulceration.

A

Enteroinvasive E.coli (EIEC)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Fecal - oral route
Manifestation:
• Fever, severe abdominal cramps, malaise and watery diarrhea (with blood)

• Clinical symptoms similar to Shigella spp. (Must be differentiated from
Shigella species)

Virulence test:

A

Enteroinvasive E.coli (EIEC)

SERENY TEST

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Similarities of EIEC with Shigella

A

• Both are gram negative, facultative anaerobic and non-spore-forming bacilli
• Non-motile
• Non-lactose fermenters
• Negative for lysine decarboxylation
• Cross reactions between 0 antigens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Differentiation is done thru:
• Their infective dose
• EIEC - has higher infective dose (____)
• Shigella - as few as____ organisms

• Acetate or mucate utilization as carbon source
- EIEC is positive

A

10^6

10

21
Q

Non-toxigenic and non-invasive
strain that causes diarrhea

A

Enteropathogenic E.coli (EPEC)

22
Q

Pathophysiology is based on its adhesive properties

Major cause of infant diarrhea in impoverished countries
Characterized by watery

amounts of mucus but no blood!

A

Enteropathogenic E.coli (EPEC)

23
Q

Pathophysiology
Infection is initiated by ____
attachment to the epithelial cells of the small intestine with subsequent effacement (destruction)
of the microvillus(attachment/effacement).

Bundle-forming pili (BFP)- mediates the initial aggregation of EPEC that leads to the formation of micro-colonies on the epithelial cell surface.

A

Enteropathogenic E.coli (EPEC)

24
Q

Enteropathogenic E.coli (EPEC)
Pathophysiology
Attachment is followed by the active secretion of proteins into the host epithelial cells through the type Ill secretion of EPEC

• __-inserted into the host’s epithelial cell membrane and functions as a receptor for an outer membrane bacterial adhesin, intimin.

• Binding of intimin to Tir - results in polymerization of actin and accumulation of cytoskeletal elements beneath the attached bacteria, loss of cell surface integrity, and death.

A

Translocated intimin receptor (Tir) -

25
Q

Pathophysiology
Attachment is followed by the active secretion of proteins into the host epithelial cells through the type Ill secretion of ____

______- causes loss of intestinal barrier function through disruption of tight junctions and induces host cell death through apoptosis.

A

Enteropathogenic E.coli (EPEC)

-Escherichia colil secreted protein F (EspF)

26
Q

Causes hemorrhagic diarrhea and colitis

A

Enterohemorrhagic E.coli (EHEC)

27
Q

EHEC strain 0157: H7-associated with hemorrhagic diarrhea, colitis, and hemolytic uremic syndrome (HUS)
Classic symptoms - watery diarrhea that progresses to bloody diarrhea with abdominal cramps, low grade fever or an absence of fever.

Stool contains no leukocytes - distinguishes it with dysentery caused by Shigella or ElEC infections

Risk factors - consumption of processed meats such as undercooked hamburgers served at fast food restaurants, unpasteurized dairy products and apple cider, bean sprouts, and spinach.

A

EHEC

28
Q

Pathophysiology: Hemorrhagic diarrhea and colitis

_____ 0157:7 (a.k.a STEC) produces two toxins: verotoxin 1 and verotoxin 2

A

Enterohemorrhagic E.coli (EHEC)

29
Q

Classic symptoms - watery diarrhea that progresses to bloody diarrhea with abdominal cramps, low grade fever or an absence of fever.

Stool contains no leukocytes - distinguishes it with dysentery caused by Shigella or ElEC infections

Risk factors - consumption of processed meats such as undercooked hamburgers served at fast food restaurants, unpasteurized dairy products and apple cider, bean sprouts, and spinach.

A

EHEC

30
Q

Verotoxin 1 -phage encoded toxin identical to the shiga toxin (Stx) produced by Shigella dysenteriae type 1.

It produces damage to Vero Cells (African Green Monkey kidney cells).

Biologically similar to, but immunologically similar from both Stx and verotoxin 1

A

Enterohemorrhagic E.coli (EHEC)

31
Q

Pathophysiology: Hemolytic Uremic Syndrome (HUS)

Endothelial cells appear to be particularly important target cells for Shiga toxins.

The toxin is transported retrograde in membrane-bound vesicles to the endoplasmic reticulum.

The A subunit induces depuration in ribosomal RNA; this leads to cessation of protein synthesis and death of the cell.

A

Enterohemorrhagic E.coli (EHEC)

32
Q

Shiga-toxin binding to proteins on the surface of glomerular endothelium and
inactivating a metalloproteinase
called von
Willebrand factor-cleaving protease (VWFCP).
Once the
VWFCP is disabled, multimers of von Willebrand Factor
(vWF) form and initiate platelet activation and cause micro thrombi
The arterioles and capillaries of the body become obstructed by the resulting complexes of activated platelets which have adhered to endothelium via large multimeric vWF

A

Enterohemorrhagic E.coli (EHEC)

33
Q

The growing thrombi lodged in smaller vessels destroy red blood cells (RBCs) as they squeeze through the narrowed blood vessels, forming schistocytes, or fragments of sheared RBCs This mechanism, known as microangiopathic hemolysis.

The consumption of platelets as they adhere to the thrombi lodged in the small vessels can lead to severe thrombocytopenia

Kidney Failure - Due to reduced blood flow leading to Ischemia and also due to the direct damage caused by the toxin to the renal endothelial cells

A

Enterohemorrhagic E.coli (EHEC)

34
Q

EHEC

Thus
the
symptoms of
HUS

A

thrombocytopenia,
microangiopathic hemolytic anemia, and kidney failure.

35
Q

Enterohemorrhagic E.coli (EHEC)
Laboratory Diagnosis

Stool culture with serotyping

Isolation using MAC using____ instead of lactose

Demonstration of a four-fold increase or greater in Shiga-toxin neutralizing antibody titer in patients’ sera with HUS

A

sorbitol

36
Q

Laboratory Diagnosis
MUG test (4-methylumbelliferyl-ß-D-glucoronide)

rarely produces the enzyme, whereas 92% of other E.coli strains do produce it.

A

EHEC 0157:7

37
Q

Note: Sorbitol-negative and MUG-negative colonies are subcultured for serotyping using anti serum for the detection of

A

E.coli 0157:H7

38
Q

Implicated in persistent watery diarrhea in infants in developing countries and in travelers to these countries

On of the few bacteria associated with chronic diarrhea and growth retardation in children

A

Enteroaggregative E.coli (EAEC)

39
Q

Characterized by their auto-agglutination
“stacked-brick” arrangement”.

A

Enteroaggregative E.coli (EAEC)

40
Q

Pathophysiology
The “stacked-brick” arrangement is mediated by______ that are similar to the bundle-forming pilus (BFP) of EPEC.

After adherence of EAEC to the surface of the intestine, mucus secretion is stimulated leading to the formation of a thick biofilm.

Thick biofilm - protects the aggregated bacteria from antibiotics and phagocytic cells.

A

Enteroaggregative E.coli (EAEC)

aggregative adherence fimbriae I (AAF1) adhesin

41
Q

Enteroaggregative E.coli (EAEC)
Pathophysiology
Two toxins are also produced:
•_______-antigenically related to the heat-stable toxin of ETEC
•_______
Both toxins induce fluid secretion

A

Enteroaggregative heat stable toxin

Plasmid encoded toxin

42
Q

Watery diarrhea with no white blood cells and red blood cells present

A

EAEC

43
Q

Most common cause of UTI, mostly occurring among females
Originate from the large intestine a sresident biota, contaminate the urethra, and ascend into the bladder and may migrate to the kidney or prostate

A

Uropathogenic E.coli

44
Q

Uropathogenic E.coli

  • primary virulence factor which uropathogenic strain used to adhere to epithelial cells and not be washed off with urine flow
  • characterized as a hemolysin that can lyse whle blood cells and innion onagocylosis and chemolaxis
  • allows uropathogenic strains to chelate iron
A

Pili

Cytolysins

Aerobatin

45
Q

Meningitis - caused by E.coli (and also group B streptococci!)

Acquired in the birth canal during delivery

May also result if contamination of the amniotic fluid occurs.

Septicemia- originates from infections in the urinary tract or gastrointestinal tract
Encapsulated strains of E.coli (possess K1 Ag) - mostly associated with neonatal meningitis and septicemia

A

Extra-intestinal Infections

46
Q

Bacteremia - E.coli is a clinically significant isolate in blood cultures from adults.
Bacteremia in adults may result from
urogenital tract infection or from Gl source.

A

Extra-intestinal Infections

47
Q

• Formerly called E.coli atypical or
enteric group lI
• Yellow pigmented colonies
• Isolated from CSF, wounds and blood

A

E. hermannii

48
Q

• Isolated from humans with infected wounds
• Half of the strains produced yellow-pigmented colonies

A

E. vulneris

49
Q

• Associated with diarrheal disease in children

A

E. albertii

Bacte LEC (40 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions