Enteric bacteria- Exam III Flashcards
1
Q
Shape and gram stain of enteric bacteria:
A
gram negative; bacilli
2
Q
Some enteric bacteria are common members of:
A
human & animal flora
3
Q
Some enteric bacteria are members of commensal groups that have become ____ due to ____
A
pathogenic due to acquired virulence factors
4
Q
What are some of the acquired virulence factors causing some commensal enteric bacteria to become pathogenic?
A
- toxins from plasmids
- toxins from bacteriophages
- pathogenicity islands
5
Q
Most enteric bacteria can be motile due to:
A
pertitrichous flagella (H-antigen)
6
Q
Some enteric bacteria are non-motile such as:
A
- shigella
- klebsiella
- yersinia
7
Q
Most enteric bacteria have ___ on the surface
A
surface pili
8
Q
responsible for adherence and enteric bacteria:
A
fimbriae
9
Q
responsible for plasmid conjugation in enteric bacteria:
A
sex pili
10
Q
Some enteric species have ____ (such as K or Vi antigen)
A
capsules
11
Q
Some enteric species have capsules such as:
A
K or Vi antigen
12
Q
List the enteric bacterial species that contain capsules:
A
- most klebsiella species
- some enterobacter species
- some E. coli species
13
Q
All enteric bacterial species contain:
A
outer membrane LPS
14
Q
The outer membrane LPS found in all enteric bacterial species may be referred to as:
A
heat-stable endotoxin
15
Q
All enteric bacterial species contain LPS (heat stable endotoxin) with:
A
enterobacterial common antigen and serotype-specific O-antigen
16
Q
Because enteric bacteria are ____, they can survive when expelled in feces
A
facultative anaerobes
17
Q
The enteric bacterial species that contain a capsule use this as an important:
A
virulence factor
18
Q
Why do all enteric bacterial species contain an outer membrane LPS?
A
because they are gram negative bacteria
19
Q
The characterization of various pathogenic E. coli strains is based on :
A
toxins produced
20
Q
A lot of pathogenic enteric bacterial species result in:
A
GI issues
21
Q
When enteric bacteria have a toxin like ____ toxin, it leads to watery diarrhea
A
cholera toxin
22
Q
When enteric bacteria have a toxin like ___ toxin, it leads to blood diarrhea
A
shiga toxin
23
Q
When enteric bacterial infection also involves neutrophils and inflammation, what may result?
A
pus in diarrhea
24
Q
Pus in diarrhea is characteristic of:
A
dysentery
25
Transmission of pathogenic enteric bacterial species causing diarrhea, bloody diarrhea and dysentery are transmitted by:
person-to-person and the "seven F's"= feces, food, fluids, fingers, flies, fomites and fornication
26
What is the enterobacterial common antigen?
Outer and inner core sugars
27
The outer and inner core sugars of enterobacterial species is referred to as:
enterobacterial common antigen
28
The LPS found in enteric bacteria is also referred to as:
Heat-stable enterotoxin
29
When must we consider that the LPS found in entrobacteria is a heat stable enterotoxin?
Becomes important when considering sterilization
30
Is present in many Bacteria like Yersinia, Salmonella, Shigella, Enteropathogenic EPEC (E. coli); also present in other species like pseudomonas and chlamydia:
Type III secretion system
31
List the enterobactrerial pathogenic species that utilize a type III secretion system:
1. Yersinia
2. Salmonella
3. Shigella
4. Enteropathogenic EPEC (E.coli)
32
List the Bacterial species that contain a Type III secretion system that are NOT enteric bacteria:
Pseudomonas and Chlamydia
33
Describe the structure of a Type III secretion system:
20-protein system that looks like a short hollow flagellum (needle)
34
What is the purpose of a Type III secretion system?
To inject a variety of species-specific toxins into host cells
35
Often times, _____ will be delivered from a bacterial cell (enteric bacteria) to a host cell via a Type III secretion system
virulence factors
36
In a type III secretion system, ____ binds to ____ to carry out the actions
Intimin binds to translocated intimin receptors
37
TIR:
Translocated initimin receptor
38
Translocated intimin receptors work for ____ and ____
Enterohemorrhagic E.coli & EPEC
39
E.coli transmission occurs through:
7F's, person-to-person, contaminated food, human waste, and animal feces (no hand washing; insect vectors)
40
E. coli virulence factors include:
1. Heat-labile enterotoxin "LT"
2. Shiga Toxin
41
Describe Heat-labile enterotoxin "LT" (Virulence factor of e.coli)
Cholera-like AB-exotoxin
42
Cholera-like AB exotoxin:
Heat-labile enterotoxin "LT"
43
Describe the steps of heat-labile enterotoxins (found in E. coli) actions:
1. ADP-ribosylation of G-protein
2. increase camp levels
3. loss of water & electrolytes
4. Watery diarrhea
44
The heat-labile enterotoxin "LT" found in E. coli is responsible for what disease?
Traveller's diarrhea
45
Describe shiva Toxin: (virulence factor of E. coli)
AB-exotoxin cytotoxin
46
AB-Exotoxin Cytotoxin:
Shiga toxin
47
Describe Shiga Toxins (found in E. coli) action:
1. Inactivation of 60S ribosome subunit by the removal of a specific adenine base from a nucleotide of 28s rRNA
2. Stops translation
3. Cell death
4. Bloody diarrhea
48
Describe
49
Foodborne enterotoxigenic ETEC E. coli may be responsible for _____ and specifically caused by ____.
watery diarrhea ; heat-labile enterotoxin "LT"
50
Food borne enterohemorrhagic EHEC E. coli O157:H7 may be responsible for ____ and specifically caused by ____.
bloody diarrhea; Shiga toxin
51
In addition to bloody diarrhea, shiva toxin may also be responsible for:
hemolytic uremic syndrome & kidney damage
52
Cholera-like AB-exotoxin responsible for ADP ribosylation of G-protein ---> Increased cAMP levels ---> loss of water & electrolytes ---> watery diarrhea
heat-labile enterotoxin "LT"
53
AB-exotoxin cytotoxin responsible for inactivation of 60s ribosome subunit by removal of a specific adenine base from a nucleotide of 28S rRNA --> stopping translation --> cell death ---> blood diarrhea
Shiga toxin
54
In _____ this set of symptoms "diarrhea with blood" is combined with intestinal cell invasion, apoptosis and neutrophillia leading to pus
shigella dysenteriae
55
Shiga toxin will often act on a:
seasonal basis
56
EHEC:
EnteroHemmorhagic E. coli (O157:H7)
57
EnteroHemmorhagic E. coli (O157:H7) clinically appears as:
1. blood diarrhea
2. hemorrhagic colitis
3. hemolytic uremic syndrome
58
What is the treatment for enterohemorrhagic E. coli (O157:H7) ?
Replenish fluids (antibiotics are contraindicated)
59
How does Uropathogenic E. coli appear clinically?
Cystitis (bladder infection)
60
For what E. coli strains are antibiotic treatments contraindicated?
EHEC
61
____ % of cystitis can be due to E. coli strains
70-90%
62
In the process of shigella infection: Shigellas are taken up by ___ and transported ___.
M cells; beneath the epithelium
63
In the process of shigella infection: What happens to the shigella once below the epithelium?
Taken up by macrophages which will result in macrophage death and release of the shigellas
64
In the process of shigella infection: The bacteria enter the ___ & ___ aspects of epithelial cells via induction of ____.
lateral and inferior; endocytosis
65
In the process of shigella infection: After the shigella enter the lateral and inferior aspects of the epithelial cells via endocytosis, what happens to the endosomes?
Endosomes are quickly lysed leaving shigellas free in the cytoplasm
66
In the process of shigella infection: How do the shigellas spread from cell to cell?
They polyermize actin to form a tail that pushes them into the next cells
67
In the process of shigella infection: What is the location of shigella multiplication?
cytoplasm
68
In the process of shigella infection: Describe the role of neutrophils
Cells infected with shigella die and slough off resulting in an intense response of acute inflammatory cells (neutrophils)
69
In the process of shigella infection: In addition to the intense response of acute inflammatory cells, what may also occur in the final stages of shigella infection?
Bleeding and abscess formation, induction of apoptosis
70
Discuss the epidemiology of shigella:
- Transmission via fecal-oral route
- Sometimes spread through contaminated food or water
- Humans generally the only source
71
What is generally the source of shigella?
Humans
72
Virulence factors of shigella include:
1. Shiga toxin
2. Cell invasion
73
What do the virulence factors of shigella ultimately lead to?
Dysentery
74
The shiga toxin virulence factor is responsible for:
bloody watery diarrhea and cell death
75
The cell invasion virulence factor of shigella bacteria is responsible for:
neutrophil death and pus formation
76
S. enterica =
salmonella
77
What illnesses may salmonella cause?
1. enteric fever
2. typhoid
78
In extreme cases, salmonella may cause death as it is associated with:
high mortality
79
Salmonella is a species of ____ bacteria
enteric bacteria
80
What is the reservoir for s. enterica?
Human reservoir
81
Aside from S. enterica using a human reservoir, many salmonella species have a ___ reservoir
poultry
82
The poultry reservoir of many salmonella species includes
The meat, the outside of the egg and even the inside of the egg in some cases
83
Many salmonella species are the cause of a ___ illness
food borne illness
84
What bacterial species causes gastroenteritis?
salmonella
85
Describe the virulence factors of salmonella:
1. Type 3 secretion
2. intracellular endosome growth in macrophages
86
Describe the virulence factors of S. typhi serovars specifically:
1. invasion into different tissues and organs via macrophages
2. Destruction of Peyers patches leading to intestinal rupture
87
Salmonellas ability to use type 3 secretion induces:
Enteric epithelial uptake via M cells
88
The intracellular endosome growth in macrophages seen with salmonella species results in:
protein secretion that prevents phagosome lysosome fusion
89
Salmonella invasion through intestinal epithelia occurs through:
1. M cell uptake through ruffles
2. Electrolyte release to lumen
3. Release of inflammatory exudate
4. Transport to lymph nodes/ transient bacteremia
90
Uptake of salmonella into the intestinal epithelia occurs through the induction of membrane ruffling that occurs by the:
remodeling of the actin cytoskeleton
91
When salmonella invoke membrane ruffling through the remodeling of actin cytoskeleton, this occurs through:
secretion of the virulence factors into the host cell
92
What occurs when salmonella invade beyond the intestinal epithelium?
transport to lymph nodes resulting in transient bacteremia
93
Enterobacter species that is responsible for causing more systemic symptoms:
S. typhii
94
In S. typhii the bacterium can pass through the epithelia of the gut and spread by:
surviving inside phagocytes
95
Where is the initial presence of S. typhii following ingestion:
small intestine
96
If the S. typhi spreads beyond the initial infection in the small intestine it will travel via ____ to the ___.
lymphatics; mesenteric lymph nodes
97
Once S. typhi reaches the mesenteric lymph nodes via the lymphatics, it will travel via ____ to cause ___.
thoracic duct to cause transient (primary) bacteremia
98
If s. typhi infection causes transient (primary) bacteremia, what will proceed?
multiplication of macrophages in the liver, spleen and bone marrow
99
When S. typhi progresses to septicemia, what results:
Fever, kidney and other organs infected
100
Why is it significant if S. typhi infects the gallbladder?
following initial infection, individuals may maintain the bacteria in their gallbladder which can be shed in the feces and creates a very important carrier state of typhoid fever
101
When s. typhi infects the gallbladder this results in:
Cholecystitis & carrier state
102
Infection of s. typhi that is maintained in the small intestines leads to:
inflammation and ulceration of Peyers patches
103
What is the significance of S. typhi getting into the kidney?
salmonella may be discharged into the urine following initial infection
104
What is the gram stain of enteric bacteria?
gram NEGATIVE
105
Vibrio cholera is a type of ____ bacteria
enteric
106
In terms of virulence factors, vibrio cholera is considered:
non-invasive (doesn't get inside the host cells)
107
Describe the gram stain and shape of vibrio cholera:
gram NEGATIVE; curved rods
108
Vibrio cholera is found in ____ & ___.
estuaries and marine environments
109
Give an example of a host that may carry vibrio cholera:
crab
110
Vibrio cholera are ____ tolerant
salt
111
Virulence factors of vibrio cholera include:
1. Toxin co-regulated pilus (tcp)
2. cholera toxin
3. ST toxin
112
The vibrio cholera toxin co-regulated plus (tcp) is virulence factor responsible for:
adhesion to the small intestinal epithelia
113
The vibrio cholera toxin virulence factor is also called:
heat-labile exotoxin "LT"
114
What is cholera toxin (heat-labile exotoxin "LT" responsible for?
Protein A causes cAMP rise leading to watery diarrhea
115
The addition virulence factor "ST" toxin contained in vibrio cholera is responsible for:
raising cGMP levels
116
In vibrio cholera, responsible for adhesion to epithelium of small intestine:
tcp (toxin co-regulated pilus)
117
The additional ST toxin in vibrio cholera contributes to watery diarrhea by:
raising cGMP levels causing electrolyte and subsequent outflow of water
118
What can cause and increase in cholera toxin binding in vibrio cholera infections?
neuraminidase
119
How does neuraminidase work to increase cholera toxin binding?
by cleaving sialic acid
120
The cholera toxin is encoded in:
bacteriophage genome called CTXphage
121
The CTXphage enters the bacterial cell through:
a toxin co-regulated pilus
122
TCP=
Toxin coregulated pilus
123
TCP production is induced with the ___, while production in other environments appears to be:
intestine; minimal
124
What is responsible for encoding the proteins that comprise the cholera toxin?
ctxA & ctxB
125
Describe the vaccine for cholera:
It is formalin killed meaning its non-pathogenic bacteria that has been inactivated but still a whole cell vaccine
126
What are the common epidemic strain of v. cholera?
Serovar O1
127
What is the newer strain of v. cholera?
serovar O139
128
List the virulence factors of vibrio cholera:
1. cholera toxin
2. toxin- coregulated pili
3. toxins
4. neurominidase
129
List the clinical features of infection with vibrio cholera:
severe watery diarrhea (disease is self-limiting as intestinal cells with surface bacteria are shed)
130
What is the treatment for vibrio cholera infection?
rehydration + electrolytes
131
What is the epidemiology of vibrio cholera:
1. fecal transmission in developing countries (can get into drinking water)
2. undercooked costal crabs
132
bacteria that looks very similar to vibrio cholera:
campylobacter jejune
133
Describe the gram stain and shape of campylobacter jejune:
gram negative & short S or curved/comma-shaped rods
134
A major virulence factor of campylobacter jejune includes:
growth in intestinal tract
135
The growth in the intestinal tract by campylobacter jejune functions to do what two things?
1. invade intestinal epithelial cells or grow below the epithelial layer
2. inflammatory response
136
A more common, but less severe source of gastroenteritis in the US compared to E. coli and Salmonella:
campylobacter jejune
137
What type of reservoir is seen with campylobacter jejune?
animal reservoir (intestinal)
138
Because campylobacter jejune utilizes an animal reservoir, this is called:
zoonosis
139
describe the transmission of campylobacter jejune:
Contaminated food (poultry/milk)
140
What percent of raw chicken contained campylobacter in the study:
89%
141
How is campylobacter typically resolved?
Without treatment in less than 1 week
142
Campylobacter disease being resolved creates:
protective immunity
