Final; Invasive Pathogens of Mucosal Surfaces Flashcards
What are the seven Fs of transmission
feces food fluids fingers flies fomites fornication
For some bacteria, as few as how many organisms can cause disease
50-100
How many organisms does it typically take to cause disease
millions
What three things work to prevent infection in humans
natural barrier defenses
innate immunity
adaptive immunity
What assists in creating a physical barrier defense
natural anatomical and physiological properties
i.e. acidity (pH 1-2 to 9)
How many cell layers protect the interior of the body from billions of microbes on mucosal surfaces
single cell layer
What are the layers of the natural barrier
water layer
mucous
glycocalyx
microvili
What are the two ways in which the pathogens can pass through the epithelial layer
invade the epithelial cells
cleave tight junctions
What is a main reason we are not always infected with gram-negative pathogens
there are so many normal flora bacteria in out intestines; out-compete infectious agents
What appears when there is a suppressed microbiota
pores; of which the infectious agents can get in
This cleaves the β 1,4-glycosidic linkages between NAM and NAG
lysozyme (aka muramidase)
This has a bacteriostatic effect via sequestering iron
lactoferrin
This disrupts the bacterial membranes of GM- and GM+ (as well as fungi)
cathelicidin
This creates pores in microbes (all microbes can be affected)
defensisn
α-defensins are produced by which cells
neutrophils and paneth cells (in the intestines)
β-defensins are produced by which cells
epithelial cells
Microboes with a low infectious dose tend to be what
acid resistant
Microbes use this to adhere to tissue to resist being shed
fimbriae/pili
This in microbial cell membranes effects of cationic antimicrobial peptides
cationic amino acids
These sequester iron in low iron environments
siderophores
These recognize microbes via PRRs
macrophages
Recognition of a PRR activates what
the microphages and the ability to kill many microbes
and the inflammatory response
These are part of the inflammatory response that also initiate the adaptive immune response and recruit other cells
cytokines
Which TLR is the most important for the pathogens we discussed
TLR-4
Inflammatory cytokines such as what can disrupt the tight junctions between epithelial cells
TNF-α; this opens a pathway for additional microbes
Microbes can develop this to resist phagocytosis
capsule
Microbes can develop mechanisms capable of neutralizing what
the phagocytic compartment of macrophages
The densest clusters of lymph nodes are found where
near mucosal tissues
This is generated in the lymph nodes
adaptive immune response
True or False
Every mucosal surface is similar in all defensive mechanisms
True
What are the two main types of invasive bacterial pathogens
salmonella spp.
shigella spp.
What type of symptoms are a result of invasive bacterial pathogens
small volume of stool
bloody stool
leukocytes in stool
tissue ulcerations
In which part of the intestine are invasive bacterial pathogens found
large intestine
What are the four species of Shigella that are distinguished by the O antigen
S. dysenteriae
S. flexneri
S. boydii
S. sonnei
How large is the inoculum size for Shigella
very small; 100-1000
This trait of Shigella facilitates survival through the stomach
acid resistance
This is controlled by a global regulatory system of genes under the control of RpoS made in the stationary phase
acid resistance
Acid resistance occurs when Shigella are grown in which condition
anaerobically
Shigella will do what in the colon
multiply and colonize
What is the series of events that happens when Shigella grows in an anaerobic condition
it will first turn on virulence genes that aid in acid resistance then when it reaches the acid, it turns on invasion genes
The mucosal surface is resistant to a Shigella invasion, but what is not
the basal surface
Shigella enters via which cells via what
M cells; via outer membrane proteins called invasion plasmid antigens
Shigella is released where and causes what
released into lamina propria, ingested by the macrophages and inflammation causes illness
When the neutrophils get into the lumen and attack a pathogen, what happens
it loosens the tight junctions
These cells will ingest Shigella facilitated by bacterial factors
epithelial cells
These lyse the phagosomal vesicle
bacterial proteins
Intracellular spread facilitated by this,
IcsA; an ATPase that causes actin polymerization
True or False
IcsA can actually go into adjacent epithelial cells by passing lamina propria
True
This develops when invaded cells die and slough off
an ulcer
True or False
All species of Shagella induce inflammatory diarrhea with leukocytes in the stool
True
What is different about S. dysenteriae type 1
it produces shiga toxin; which kills intestinal epithelial and endothelial cells and disrupts Na absorption
These diseases are caused by salmonella
gastroenteritis
typhoid fever
How is salmonella spread
fecal (human or animal) - oral transmission
How large of an inoculum is required for salmonella
relatively large; 10-100 million
Which microbe is more acid sensitive; salmonella or shigella
salmonella
Salmonella in a low pH triggers what
expression of at least 40 proteins found on pathogenicity islands on large virulence plasmids
When salmonella approaches the cells surface, what happens
induces the activity of cell signaling pathways and cause an increase in cellular Ca++
When salmonella induces the cell signaling and Ca increase, what also happens
it induces surface ruffles and uptake of the organisms (microbe directed phagocytosis)
Unlike shigella, salmonella does what upon entering vesicles
remains within the vesicle for many hours
Once salmonella is released into lamina propria what happens
it induces NaCl loss from the host cell
Macrophages engulf most of the salmonella, but some escape and cause what
transient bacteremia
What is different about typhoid
it will enter the lymphatic system and will survive and grow in macrophages throughout the body
What is dangerous about the typhoid spread
strictly a human reservoir
asymptomatic carriers (typhoid Mary)
carriers have colonized gall bladders
True or False
Invasive enteric pathogens are not able to respond to environmental changes
False; they do respond
How are invasive enteric pathogens identified
based upon symptoms and stool cultures
Antibiotic resistance was first identified where
in Shigella
