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P2: Bacteriology > Enterobacteriaceae > Flashcards

Enterobacteriaceae Flashcards

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1
Q

Pathogenesis:

E. coli is widely recognized as the most common cause of UTIs in humans

A

Uropathogenic E. coli (UPEC)

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2
Q

Virulence factors of Escherichia coli

A

PILI
CYTOLYSIN
AEROBACTIN

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3
Q

adhere to epithelial cells and not be washed out with urine flow.

A

PILI

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4
Q

kill immune cells and inhibit phagocytosis and chemotaxis

A

CYTOLYSIN

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5
Q

allow bacterial cells to chelate iron

A

AEROBACTIN

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6
Q

5 MAJOR CATEGORIES in Gastrointestinal Pathogens of Escherichia coli

A

I. Enterotoxigenic Escherichia coli (ETEC)
II. Enteroinvasive Escherichia coli (EIEC)
III. Enteropathogenic Escherichia coli (EPEC)
IV. Enterohemorrhagic Escherichia coli (EHEC)
V. Enteroadherent Escherichia coli, which includes:
a. diffusely adherent Escherichia coli (DAEC)
b. enteroaggregative Escherichia coli (EAEC).

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7
Q

ENTEROADHERENT E. coli infections:

A

Diarrheal syndromes (absence of WBCs and RBCs) & UTI

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8
Q

types of ENTEROADHERENT E. coli:

Associated with both UTI and GIT infections

A

DAEC (Diffusely Adherent E. coli)

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9
Q

types of ENTEROADHERENT E. coli:

Causes cystitis in children and acute pyelonephritis in pregnant women

A

DAEC (Diffusely Adherent E. coli)

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10
Q

types of ENTEROADHERENT E. coli:

Causes diarrhea by adhering to the surface of intestinal mucosa

A

EAEC (Enteroaggregative E. coli)

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11
Q

types of ENTEROADHERENT E. coli:

Adheres to HEp2 cells, packed in a “stacked-brick” pattern

A

EAEC (Enteroaggregative E. coli)

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12
Q

ENTEROTOXIGENIC E. coli infection:

A

Traveler’s diarrhea a.k.a Montezuma’s revenge or La Tourista

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13
Q

Colonization of ENTEROTOXIGENIC E. coli

A

Proximal small intestines

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14
Q

Infective dose of ENTEROTOXIGENIC E. coli

A

10^6 to 10^10

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15
Q

ENTEROTOXIGENIC E. coli Produces two (2) toxins:

A

Heat-labile Toxin (LT)
Heat-stable Toxin (ST)

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16
Q

ENTEROTOXIGENIC E. coli toxins:

Similar to choleragen toxin from Vibrio cholera

A

Heat-labile Toxin (LT)

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17
Q

ENTEROTOXIGENIC E. coli toxins:

Activates adenylate cyclase causing hypersecretion of both electrolytes and fluids into the intestinal lumen leading to water diarrhea

A

Heat-labile Toxin (LT)

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18
Q

ENTEROTOXIGENIC E. coli toxins:

Stimulates guanylate cyclase which leads to hypersecretion of electrolytes and water into the intestinal lumen

A

Heat-stable Toxin (ST)

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19
Q

ENTEROINVASIVE E. coli infection:

A

Dysentery-like/Shigella-like Infection;
Water diarrhea with WBCs

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20
Q

Infective dose of ENTEROINVASIVE E. coli

A

> 10^6

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21
Q

(E. coli)
Pathogenesis:
Produces dysentery with direct penetration, invasion and destruction of the intestinal mucosa

A

EIEC: ENTEROINVASIVE E. coli

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22
Q

Infection of EPEC: ENTEROPATHOGENIC E. coli

A

Infantile Diarrhea

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23
Q

(Escherichia coli)

Stool typically contains large amount of mucus but apparent blood is not
present

A

EPEC: ENTEROPATHOGENIC E. coli

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24
Q

(Escherichia coli)

Lacked the toxins of ETEC and lacks the invasiveness of EIEC

A

EPEC: ENTEROPATHOGENIC E. coli

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25
Pathogenesis of EPEC: ENTEROPATHOGENIC E. coli
Adhesive property – attach to the borders of the intestinal cells
26
EHEC: ENTEROHEMORRHAGIC E. coli is also known as:
Verotoxic E. coli (VTEC) / STEC
27
Infection of EHEC: ENTEROHEMORRHAGIC E. coli
Hemorrhagic colitis, HUS, Bloody diarrhea without WBC
28
(Escherichia coli) Associated with ingestion of poorly cooked meats
EHEC: ENTEROHEMORRHAGIC E. coli
29
Virulence Factors of EHEC
Verotoxin I Verotoxin II
30
Virulence Factors of EHEC: Identical to Shiga toxin produced by S. dysenteriae
Verotoxin I
31
Virulence Factors of EHEC: Can be neutralized by antibodies to Shiga toxin
Verotoxin I
32
Virulence Factors of EHEC:
Biologically similar but immunologically different from Shiga toxin and Verotoxin I
33
E. coli strain serotype of hamburger-disease (EHEC)
0157:H7
34
E. coli strain serotype Associated with hemorrhagic diarrhea and HUS
0157:H7 (Hamburger-disease)
35
Tests for EHEC
• MUG test (neg) and Sorbitol non-fermenter • SMAC: colorless colonies • Stool examination: Stool of patients with EHEC contains no WBCs
36
(Escherichia coli) Culture identification
MacConkey EMB
37
Culture of E. coli where pink-red (lactose-fermenting) colony with surrounding area of precipitated bile salts
MacConkey
38
Culture of e-coli where there is an appearance of green metallic sheen
EMB
39
IMViC REACTION of Escherichia coli
++00
40
Escherichia coli IDENTIFICATION: BIOCHEMICAL REACTIONS To differentiate bacteria based on their ability to ferment glucose, lactose and/or sucrose, and to reduce sulfur to hydrogen sulfide.
TSI ( TRIPLE SUGAR IRON)
41
TSI ( TRIPLE SUGAR IRON) It is indicative of dextrose fermentation only.
alkaline/acid (red slant/yellow butt)
42
TSI ( TRIPLE SUGAR IRON) It indicates the fermentation of dextrose, lactose and/or sucrose.
acid/acid (yellow slant/yellow butt)
43
TSI ( TRIPLE SUGAR IRON) Absence of carbohydrate fermentation results.
alkaline/alkaline (red slant, red butt)
44
TSI ( TRIPLE SUGAR IRON) Occurs in the presence of H2S
Blackening of the medium
45
TSI ( TRIPLE SUGAR IRON) Bubbles or cracks in the agar indicate the production of
gas ( formation of CO2and H2)
46
Escherichia coli IDENTIFICATION: BIOCHEMICAL REACTIONS TSI
• Fermentsglucose,lactose,sucrose • Withgasproduction • DoesNOTproduceH2S
47
Escherichia coli IDENTIFICATION: BIOCHEMICAL REACTIONS ONPG TEST
Positive
48
Escherichia coli IDENTIFICATION: BIOCHEMICAL REACTIONS Urease
Negative
49
tests organisms for the ability to deaminate lysine or decarboxylate lysine.
LIA (Lysine iron agar)
50
Lysine Decarboxylation (detected in butt): POSITIVE
Purple slant/purple butt (alkaline)
51
Lysine Decarboxylation (detected in butt): NEGATIVE
Purple slant/yellow butt (acid)
52
Lysine Decarboxylation (detected in butt): the butt reaction may be masked by H2S production
Positive
53
Lysine Decarboxylation (detected in butt): fermentation of glucose only
Negative
54
Lysine Deamination (detected on slant): Positive Negative
+ : Red slant - : Slant remains purple
55
H2S Production: Black precipitate
Positive
56
H2S Production: No black color development
Negative
57
H2S Production: demonstrated by the presence of bubbles or cracks in the medium
Gas production
58
Primary Intestinal Pathogens
Salmonella Shigella Yersinia
59
The most pathogenic enterobacteria for humans causing enteric fever and acute gastroenteritis
Salmonella
60
In humans; the cause of two diseases called salmonellosis: resulting from bacterial invasion of the bloodstream
enteric fever (typhoid)
61
In humans; the cause of two diseases called salmonellosis: resulting from a foodborne infection/intoxication
acute gastroenteritis
62
MOT: - Ingestion of contaminated animal food products or improperly cooked poultry, milk, eggs and dairy products
Salmonella
63
Salmonella spp. VIRULENCE FACTORS
• FIMBRIAE • EXOTOXIN
64
Salmonella spp. ANTIGENIC STRUCTURES
Somatic or O antigens Flagellar or H antigens Vi surface antigen
65
Salmonella spp. MAC
clear, colorless colonies
66
Salmonella spp. HEA (Hektoen – Enteric Agar)
Green colonies with black centers
67
Salmonella spp. XLD (Xylose – Lysine – Deoxycholate)
Red colonies with black centers
68
Preferred medium for S. typhi – produces metallic colonies with ring
BSA (Bismuth Sulfite Agar)
69
Salmonella spp. SSA (Salmonella Shigella Agar)
Colorless colonies with black center
70
THREE (3) GENERAL CATEGORIES OF SALMONELLA INFECTION
I. Enteric fever II. Gastroenteritis III. Bacteremia
71
Causative agent for Typhoid fever
S. typhi
72
Salmonella spp. CLINICAL SIGNIFICANCE MOT: Ingestion of contaminated food originating from infected individuals or carriers; direct transmission through fomites is also possible
Enteric fever
73
Salmonella spp. CLINICAL SIGNIFICANCE Symptoms: malaise, anorexia, lethargy, myalgia and continuous frontal dull headache, “rose- spots” appear during the 2nd week of fever
Enteric fever
74
Salmonella spp. CLINICAL SIGNIFICANCE Complications: necrotizing cholecystitis and Peyer’s patches
Enteric fever
75
Salmonella spp. CLINICAL SIGNIFICANCE One of the most common forms of food poisoning
Gastroenteritis
76
Causative agent of gastroenteritis
S. enterica subsp. Enterica
77
Peanut-butter outbreak causative agent
S. sero. Typhimurium
78
Salmonella spp. CLINICAL SIGNIFICANCE Used of contaminated cooking utensils that can spread the bacteria to other food and inadequate refrigeration
Gastroenteritis
79
Salmonella spp. CLINICAL SIGNIFICANCE Sources of infection: Poultry, dairy products and handling of pets
Gastroenteritis
80
Salmonella spp. CLINICAL SIGNIFICANCE Symptoms: nausea, vomiting, chills, watery diarrhea and chills
Gastroenteritis
81
Salmonella spp. CLINICAL SIGNIFICANCE Occurs with and without extraintestinal foci of infection caused by nontyphoidal Salmonella (S. Typhimurium, S. Paratyphi, and S. Cholerasuis)
Bacteremia
82
Salmonella spp. CLINICAL SIGNIFICANCE Characterized by: Prolonged fever and intermittent bacteremia

P2: Bacteriology (11 decks)

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