1-23 Enteric Bacteria Flashcards Preview

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Flashcards in 1-23 Enteric Bacteria Deck (17):

List at least 4 pathogenic enterobacteriaceae and at least three defining traits of the group

E.coli, Y.enterocolitica, and genera Shigella and Salmonella

Gram -
non-spore forming
straight rod shaped
facultative anaerobes


describe the importance of horizontal gene transfer to the group's pathogenic potential

enteric bacteria are particularly inclined to sharing DNA via horizontal transfer.

-Leads to extreme abx resistance being a common trait


describe process of antimicrobial sensitivity testing

1. smear agar with bacteria
2. disks of antibiotic on plate
3. incubate
4. examine - zones of clearing indicate effective antibiotics.
5. After measuring, compare to table to determine most effective abx


importance of pili and type III secretion systems as virulence factors for foodborne enterobacteria

bacteria ANCHOR on interinal epithelia via pilli. otherwise get washed away.

type III secretion systems are involved in adhesion, delivery of enterotoxin, and macrophage subversion.


describe the typical function of type III secretion systems in the pathogenesis of enterocolitis and/or spread to lymph nodes

in salmonella - uses type III to render macrophage uptake ineffective. Will either
1. subvert macrophages and infect epithelial cells
2. or ride macrophage to the lymph nodes, allowing for major organ invasion.


describe how Y.enterocolitica and S. typhi subvert the macrophages

both use as trojan horse
y.entero - local lymph node infection and false appendicitis

s.typhi - systemic lymph node infection


define Hemolytic-uremic syndrome

HUS - when shigella and enterohemmorhagic E.coli escape gut they release shiga toxin to bloodstream.


define reactive arthritis

autoimmune disease triggered by infection. patients positive for human leukocyte antigen b27 may develope after an infection by shigella, salmonella, yersinia, campylobacter, or chlamydia.

conjunctivitis, urethritis, arthritis
"cant see, cant pee or climb a tree"



why are non foodborne opportunitic enterobacteriaceae pathogens difficult to treat?

ICU bugs - difficult to treat and typically only cause illness in those already sick. Sometimes treatment must occur before lab results arrive. Major nosocomial pathogens that infect catheters, wounds.


examples of ICU bugs?

Klebsiella, Enterobacter, Serratia, Proteus, Providencia, and Morganella


foodborne enterobacteria infections are generally ________ and prevented by?


water treatment, handwashing, food pasteurization, and cooking.


Enterobacteriaceae is a ________ grouping including foodborne members (4) and opportunistic pathogens (6)

Shigella, E. coli, Salmonella, and Yersinia

Klebsiella, Enterobacter, Serratia, Proteus, Providencia, and Morganella.


important virulence factors in the gut

pili (for attaching – the GI and urinary tract constantly push contents out unless they are anchored)

type 3 secretion systems (for adhesion, enterotoxins, subverting gut macrophage).


enterobacteriaceae often allow themselves to be...

sampled by M-Cells in the peyers patches. Then alter local macrophages for bacterial survival/spread into the exterior surface of the gut (using T3SS).

Some use macrophages as trojan horses to lymph nodes locally (y.enterocolicita) false appendicities

or system wide (s.typhi, typhoid fever)


what traits are shared by all the enterobacteriacae?

gram - rods
not strictly aerobic
problematic antibody resistances


what enteric bacterial infection may lead to HUS?

tell-tale sign?

shigella or eneterohemmorghenic e.coli strains

schitocytes - broken blood cells in smear


non-foodborne enterobacteriaeceae are often

opportunistic pathogens, normal flora gone bad

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