Enteric bacteria- Exam III Flashcards by Abagayle Moody

Shape and gram stain of enteric bacteria:

gram negative; bacilli

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Some enteric bacteria are common members of:

human & animal flora

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Some enteric bacteria are members of commensal groups that have become ____ due to ____

pathogenic due to acquired virulence factors

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What are some of the acquired virulence factors causing some commensal enteric bacteria to become pathogenic?

toxins from plasmids
toxins from bacteriophages
pathogenicity islands

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Most enteric bacteria can be motile due to:

pertitrichous flagella (H-antigen)

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Some enteric bacteria are non-motile such as:

shigella
klebsiella
yersinia

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Most enteric bacteria have ___ on the surface

surface pili

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responsible for adherence and enteric bacteria:

fimbriae

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responsible for plasmid conjugation in enteric bacteria:

sex pili

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Some enteric species have ____ (such as K or Vi antigen)

capsules

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Some enteric species have capsules such as:

K or Vi antigen

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List the enteric bacterial species that contain capsules:

most klebsiella species
some enterobacter species
some E. coli species

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All enteric bacterial species contain:

outer membrane LPS

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The outer membrane LPS found in all enteric bacterial species may be referred to as:

heat-stable endotoxin

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All enteric bacterial species contain LPS (heat stable endotoxin) with:

enterobacterial common antigen and serotype-specific O-antigen

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Because enteric bacteria are ____, they can survive when expelled in feces

facultative anaerobes

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The enteric bacterial species that contain a capsule use this as an important:

virulence factor

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Why do all enteric bacterial species contain an outer membrane LPS?

because they are gram negative bacteria

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The characterization of various pathogenic E. coli strains is based on :

toxins produced

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A lot of pathogenic enteric bacterial species result in:

GI issues

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When enteric bacteria have a toxin like ____ toxin, it leads to watery diarrhea

cholera toxin

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When enteric bacteria have a toxin like ___ toxin, it leads to blood diarrhea

shiga toxin

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When enteric bacterial infection also involves neutrophils and inflammation, what may result?

pus in diarrhea

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Pus in diarrhea is characteristic of:

dysentery

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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

What is the enterobacterial common antigen?

Outer and inner core sugars

The outer and inner core sugars of enterobacterial species is referred to as:

enterobacterial common antigen

The LPS found in enteric bacteria is also referred to as:

Heat-stable enterotoxin

When must we consider that the LPS found in entrobacteria is a heat stable enterotoxin?

Becomes important when considering sterilization

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

List the enterobactrerial pathogenic species that utilize a type III secretion system:

1. Yersinia 2. Salmonella 3. Shigella 4. Enteropathogenic EPEC (E.coli)

List the Bacterial species that contain a Type III secretion system that are NOT enteric bacteria:

Pseudomonas and Chlamydia

Describe the structure of a Type III secretion system:

20-protein system that looks like a short hollow flagellum (needle)

What is the purpose of a Type III secretion system?

To inject a variety of species-specific toxins into host cells

Often times, _____ will be delivered from a bacterial cell (enteric bacteria) to a host cell via a Type III secretion system

virulence factors

In a type III secretion system, ____ binds to ____ to carry out the actions

Intimin binds to translocated intimin receptors

TIR:

Translocated initimin receptor

Translocated intimin receptors work for ____ and ____

Enterohemorrhagic E.coli & EPEC

E.coli transmission occurs through:

7F's, person-to-person, contaminated food, human waste, and animal feces (no hand washing; insect vectors)

E. coli virulence factors include:

1. Heat-labile enterotoxin "LT" 2. Shiga Toxin

Describe Heat-labile enterotoxin "LT" (Virulence factor of e.coli)

Cholera-like AB-exotoxin

Cholera-like AB exotoxin:

Heat-labile enterotoxin "LT"

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

The heat-labile enterotoxin "LT" found in E. coli is responsible for what disease?

Traveller's diarrhea

Describe shiva Toxin: (virulence factor of E. coli)

AB-exotoxin cytotoxin

AB-Exotoxin Cytotoxin:

Shiga toxin

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

Describe

Foodborne enterotoxigenic ETEC E. coli may be responsible for _____ and specifically caused by ____.

watery diarrhea ; heat-labile enterotoxin "LT"

Food borne enterohemorrhagic EHEC E. coli O157:H7 may be responsible for ____ and specifically caused by ____.

bloody diarrhea; Shiga toxin

In addition to bloody diarrhea, shiva toxin may also be responsible for:

hemolytic uremic syndrome & kidney damage

Cholera-like AB-exotoxin responsible for ADP ribosylation of G-protein ---> Increased cAMP levels ---> loss of water & electrolytes ---> watery diarrhea

heat-labile enterotoxin "LT"

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

In _____ this set of symptoms "diarrhea with blood" is combined with intestinal cell invasion, apoptosis and neutrophillia leading to pus

shigella dysenteriae

Shiga toxin will often act on a:

seasonal basis

EHEC:

EnteroHemmorhagic E. coli (O157:H7)

EnteroHemmorhagic E. coli (O157:H7) clinically appears as:

1. blood diarrhea 2. hemorrhagic colitis 3. hemolytic uremic syndrome

What is the treatment for enterohemorrhagic E. coli (O157:H7) ?

Replenish fluids (antibiotics are contraindicated)

How does Uropathogenic E. coli appear clinically?

Cystitis (bladder infection)

For what E. coli strains are antibiotic treatments contraindicated?

EHEC

____ % of cystitis can be due to E. coli strains

70-90%

In the process of shigella infection: Shigellas are taken up by ___ and transported ___.

M cells; beneath the epithelium

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

In the process of shigella infection: The bacteria enter the ___ & ___ aspects of epithelial cells via induction of ____.

lateral and inferior; endocytosis

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

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

In the process of shigella infection: What is the location of shigella multiplication?

cytoplasm

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)

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

Discuss the epidemiology of shigella:

- Transmission via fecal-oral route - Sometimes spread through contaminated food or water - Humans generally the only source

What is generally the source of shigella?

Humans

Virulence factors of shigella include:

1. Shiga toxin 2. Cell invasion

What do the virulence factors of shigella ultimately lead to?

Dysentery

The shiga toxin virulence factor is responsible for:

bloody watery diarrhea and cell death

The cell invasion virulence factor of shigella bacteria is responsible for:

neutrophil death and pus formation

S. enterica =

salmonella

What illnesses may salmonella cause?

1. enteric fever 2. typhoid

In extreme cases, salmonella may cause death as it is associated with:

high mortality

Salmonella is a species of ____ bacteria

enteric bacteria

What is the reservoir for s. enterica?

Human reservoir

Aside from S. enterica using a human reservoir, many salmonella species have a ___ reservoir

poultry

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

Many salmonella species are the cause of a ___ illness

food borne illness

What bacterial species causes gastroenteritis?

salmonella

Describe the virulence factors of salmonella:

1. Type 3 secretion 2. intracellular endosome growth in macrophages

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

Salmonellas ability to use type 3 secretion induces:

Enteric epithelial uptake via M cells

The intracellular endosome growth in macrophages seen with salmonella species results in:

protein secretion that prevents phagosome lysosome fusion

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

Uptake of salmonella into the intestinal epithelia occurs through the induction of membrane ruffling that occurs by the:

remodeling of the actin cytoskeleton

When salmonella invoke membrane ruffling through the remodeling of actin cytoskeleton, this occurs through:

secretion of the virulence factors into the host cell

What occurs when salmonella invade beyond the intestinal epithelium?

transport to lymph nodes resulting in transient bacteremia

Enterobacter species that is responsible for causing more systemic symptoms:

S. typhii

In S. typhii the bacterium can pass through the epithelia of the gut and spread by:

surviving inside phagocytes

Where is the initial presence of S. typhii following ingestion:

small intestine

If the S. typhi spreads beyond the initial infection in the small intestine it will travel via ____ to the ___.

lymphatics; mesenteric lymph nodes

Once S. typhi reaches the mesenteric lymph nodes via the lymphatics, it will travel via ____ to cause ___.

thoracic duct to cause transient (primary) bacteremia

If s. typhi infection causes transient (primary) bacteremia, what will proceed?

multiplication of macrophages in the liver, spleen and bone marrow

When S. typhi progresses to septicemia, what results:

Fever, kidney and other organs infected

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

When s. typhi infects the gallbladder this results in:

Cholecystitis & carrier state

Infection of s. typhi that is maintained in the small intestines leads to:

inflammation and ulceration of Peyers patches

What is the significance of S. typhi getting into the kidney?

salmonella may be discharged into the urine following initial infection

What is the gram stain of enteric bacteria?

gram NEGATIVE

Vibrio cholera is a type of ____ bacteria

enteric

In terms of virulence factors, vibrio cholera is considered:

non-invasive (doesn't get inside the host cells)

Describe the gram stain and shape of vibrio cholera:

gram NEGATIVE; curved rods

Vibrio cholera is found in ____ & ___.

estuaries and marine environments

Give an example of a host that may carry vibrio cholera:

crab

Vibrio cholera are ____ tolerant

salt

Virulence factors of vibrio cholera include:

1. Toxin co-regulated pilus (tcp) 2. cholera toxin 3. ST toxin

The vibrio cholera toxin co-regulated plus (tcp) is virulence factor responsible for:

adhesion to the small intestinal epithelia

The vibrio cholera toxin virulence factor is also called:

heat-labile exotoxin "LT"

What is cholera toxin (heat-labile exotoxin "LT" responsible for?

Protein A causes cAMP rise leading to watery diarrhea

The addition virulence factor "ST" toxin contained in vibrio cholera is responsible for:

raising cGMP levels

In vibrio cholera, responsible for adhesion to epithelium of small intestine:

tcp (toxin co-regulated pilus)

The additional ST toxin in vibrio cholera contributes to watery diarrhea by:

raising cGMP levels causing electrolyte and subsequent outflow of water

What can cause and increase in cholera toxin binding in vibrio cholera infections?

neuraminidase

How does neuraminidase work to increase cholera toxin binding?

by cleaving sialic acid

The cholera toxin is encoded in:

bacteriophage genome called CTXphage

The CTXphage enters the bacterial cell through:

a toxin co-regulated pilus

TCP=

Toxin coregulated pilus

TCP production is induced with the ___, while production in other environments appears to be:

intestine; minimal

What is responsible for encoding the proteins that comprise the cholera toxin?

ctxA & ctxB

Describe the vaccine for cholera:

It is formalin killed meaning its non-pathogenic bacteria that has been inactivated but still a whole cell vaccine

What are the common epidemic strain of v. cholera?

Serovar O1

What is the newer strain of v. cholera?

serovar O139

List the virulence factors of vibrio cholera:

1. cholera toxin 2. toxin- coregulated pili 3. toxins 4. neurominidase

List the clinical features of infection with vibrio cholera:

severe watery diarrhea (disease is self-limiting as intestinal cells with surface bacteria are shed)

What is the treatment for vibrio cholera infection?

rehydration + electrolytes

What is the epidemiology of vibrio cholera:

1. fecal transmission in developing countries (can get into drinking water) 2. undercooked costal crabs

bacteria that looks very similar to vibrio cholera:

campylobacter jejune

Describe the gram stain and shape of campylobacter jejune:

gram negative & short S or curved/comma-shaped rods

A major virulence factor of campylobacter jejune includes:

growth in intestinal tract

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

A more common, but less severe source of gastroenteritis in the US compared to E. coli and Salmonella:

campylobacter jejune

What type of reservoir is seen with campylobacter jejune?

animal reservoir (intestinal)

Because campylobacter jejune utilizes an animal reservoir, this is called:

zoonosis

describe the transmission of campylobacter jejune:

Contaminated food (poultry/milk)

What percent of raw chicken contained campylobacter in the study:

89%

How is campylobacter typically resolved?

Without treatment in less than 1 week

Campylobacter disease being resolved creates:

protective immunity

Enteric bacteria- Exam III Flashcards

(142 cards)