Enteric Bacteria Flashcards
What are enteric bacteria?
bacteria that cause gut infections
What are some ENTERIC bacteria? (11)
Shigella E. coli Salmonella Y. en-te-ro-co-li-ti-ca Y. pseudotuberculosis Vibrio Campylobacter Helicobacter Bacteroides/Preveotella Clostridium Listeria
What are the three main groups the enterobacteriaceae are classified into?
Major Foodborne
Minor Foodborne
ICU Bugs
What are the major foodborne enterobacteriaceae? (3)
Shigella
E. coli
Salmonella
What are the minor food borne enterobacteriaceae? (2)
Y. enterocolitica
Y. pseudotuberculosis
What are the ICU bugs? (2x3)
- Kleb-siella/Enterobacter/Serra-tia
- Proteus/Providencia/Mor-ganella
What are the DEFINING characteristics of enterobacteriaceae? (7)
Gram (-) Non-sporulating Straight Rods Facultative Aerobes Catalase + Oxidase - Glucose Fermenters
COMMON characteristics of enterobacteriaceae?
Promiscuous to new DNA
How does promiscuous to new DNA play a role?
Acquired Gut Virulence Factors
Ab resistance
What are two types of acquired virulence factors?
- -pili for adhesion
- -T3SS for adhesion and subverting Macrophages
What is the difference between commensalism E.coli and uropathogenic E.coli?
The acquisition of “P” Fimbriae (do to DNA uptake) –> adheres to bacteria inside urinary track –> UTI’s and kidney failure if not treated
Who are more susceptible to UTI’s?
Women of child bearing years
Individuals with diabetes
What are the addition of T3SS as virulence factors helpful for in Enterobacteriaceae?
Subverting Macrophages
They can directly pass materials from inside the bacteria (such as exotoxins) directly into the inside of the host cell
How do enterobacteriaceae get into the host cell? (2)
They either force the cell to form an actin bundle, which the bacteria can easily adhere to
Or they can subvert the endocytosis process and either
-use the endosome as a growth compartment
-escape the endosome and travel around cytosol freely
What is the typical infection of major food borne enterobacteriaceae?
Generally these bacteria can not penetrate the exterior part of the lumen. But they use M-cells to get into the lumen. They subvert the M-cells normal process of sampling, forcing the M-cells to refrain from killing them. Allowing the bacteria to pass through and reach the Macrophage. The MO then undergoes apoptosis–>releasing the bacteria into the sterile side. From here they attack the inside of the lumen and do a backward infection (intracellular infection)
What are M cells?
They are in charge of immunosurveillance of the lumen. The purposely pick up particle and microorganisms, sampling them and raising an immune response if necessary
What VF do these enterobacteriaceae need?
Ones to subvert endocytosis
Ones to induce apoptosis
What is an antimicrobial sensitivity assay?
It is to test for resistance of Antibiotics in certain bacteria
How do you perform it?
Spread an even layer of bacteria on plate
Place disk (previously soaked in diff antibiotics) on plate
Incubate
Check for clearance
Refer to the table to see if clearance is significant
Salmonella
Gram (-)
Motile - flagella
> 2500 serovars exist
Usually aquired from contaminated food
Why would it be difficult to make a vaccine against Salmonella?
There are far too many serovars (types)
What is the pathogenesis of Salmonella?
Enterocolitis
Enteric Fever
–more server –> typhoid fever
Enterocolitis causes?
Inflammation, diarrhea, nausea, vomiting
About Enterocolitis
- Immune response restricts it to the gut, spreading to the blood stream is rare
- Need a high infectious dose
- Gastric acid kills most (ppl on anti-acids are more susceptible)
- Bacteria attach by fimbriae to cells lining the intestinal lumen
- ->specifically M-cells of the Peyer’s patch
