18 Questions
How does the increase in intracellular calcium levels in enteropathogenic E.coli affect the host cell?
The increase in intracellular calcium levels activates actin-severing enzymes and protein kinases, which then lead to vesiculation and disruption of the microvilli.
What is the role of protein kinases in the pathogenesis of enteropathogenic E.coli infection?
The activation of protein kinases by the increase in intracellular calcium levels allows for maximal activation of the protein kinases, resulting in major changes to the cytoskeleton and alterations in the permeability of the membrane to ions.
How do the changes in ion permeation caused by enteropathogenic E.coli infection lead to the secretory diarrhea associated with this disease?
The changes in ion permeation result in ion secretion and reduction in absorption, resulting in the secretory diarrhea that is the hallmark of this disease.
What is the significance of the large plasmid found in a majority of enteropathogenic E.coli isolates?
The large plasmid found in a majority of enteropathogenic E.coli isolates codes for its adhesive properties, which is crucial for the bacteria to attach to the host epithelium.
How do microbial biofilms develop, and what is their role in the context of medical devices?
Microbial biofilms develop when microorganisms adhere irreversibly to a submerged surface and produce extracellular polymers that facilitate adhesion and provide a structural matrix. In the context of medical devices, biofilms can form on the surface of indwelling devices that have been inserted into the body.
What are some local anatomic conditions that can influence microbial growth?
Amounts and types of nutrients available, pH, oxidation reduction potentials, resistance to local antibacterial substances
What is the significance of the increase in intracellular calcium levels in the pathogenesis of enteropathogenic E.coli infection?
The increase in intracellular calcium levels is a key event that activates actin-severing enzymes and protein kinases, leading to disruption of the host cell's microvilli and changes in the cytoskeleton and membrane permeability, which are crucial for the bacteria to establish a successful infection.
How do bacteria adhere to specific epithelial cells?
Through the presence of bacterial pili/fimbriae or other microbial surface components
What is the role of microbial interactions in determining their prevalence in the flora?
Competition for nutrients, inhibition of growth by metabolic products produced by other microorganisms
Why is the normal microbial flora important in health?
Participates in human nutrition and metabolism
What is the mechanism that allows microorganisms to grow and multiply while avoiding removal by surface fluids and peristalsis?
Adherence to specific receptor sites on epithelial cells
How do some microorganisms avoid removal by the flushing effects of surface fluids and peristalsis?
By adhering to specific receptor sites on epithelial cells
How do biofilms make microorganisms resistant to antibiotic treatment?
Microorganisms within biofilms are imbedded within the extracellular polymer matrix, which makes them highly resistant to antibiotic treatment.
Why do individuals with biofilm infections often require surgical replacement of the prosthesis or removal of the catheter or central line?
These infections are refractory to antimicrobial therapy, so surgical intervention is required to remove the infected device.
Why is iron acquisition a critical requirement for microorganisms once they adhere to a body site?
Iron is required for the subsequent growth and multiplication of the microorganism after it adheres to a body site.
Why is the concentration of usable iron low in the human body?
The majority of iron in the human body is bound by lactoferrin, transferrin, ferritin, and hemin, leaving little free iron available to support microbial growth.
What mechanisms have microorganisms evolved to acquire iron from their environments?
Microorganisms have evolved a number of mechanisms for the acquisition of iron from their environments.
How do biofilms provide an example of iatrogenic activities that create new niches for microorganisms to exploit as causes of human infection?
Biofilm formation on embedded plastic and stainless steel devices, which are used in well-intentioned medical treatments, provides an example of how these activities create new environments for microorganisms to colonize and cause infections.
Test your knowledge on the mechanisms used by microorganisms to adhere to host cells and trigger pathogenic events, illustrated by the example of enteropathogenic E.coli. Explore how intracellular calcium levels, actin-severing enzymes, and protein kinases contribute to vesiculation and disruption of microvilli.
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