Antimicrobials Flashcards
What do coordinate or global regulatory circuits do?
control the expression of genes encoding multiple virulence factors in some bacteria
What is quorum sensing?
a signaling system between bacterial cells that regulates the transcription of multiple genes
What is quorum sensing dependent on?
the production of one or more diffusable signal molecules called autoinducers or pheromones which enable a bacterium to monitor its own population density
Quorum sensing is an example of _____ _____ _____ in single-celled prokaryotic organisms.
coordinated multicellular behavior
What is quorum sensing used to regulate?
diverse physiological processes such as production of virulence determinants, swarming, bioluminescence and antibiotic synthesis
What are defensins?
antibacterial polypeptides that are the major effector mechanism of the natural immune system
What are some cell types tat produce defensins?
epithelial cells of the intestine, respiratory tract, mammary gland, skin, kidney, eye, and tongue, and granulocytes
What is the function of defensins?
they behave as amphiphiles that bind to the target cell membrane and form a pore or channel, attack fungi and eukaryotic cells, and stimulate wound healing by inducing synthesis of other compounds
What does the activation of toll-like receptors result in?
the production of inflammatory mediators and other products
What is the role of toll-like receptors on immune cells?
they signal that bacteria are attacking the cell
What defense mechanisms does the skin have?
mechanical barrier of dry, nonliving tissue, fatty acids, lysozyme, and normal flora
What are the defense mechanisms of mucous membranes?
mucus, cilia, phagocytic cells, saliva, stomach acid, proteolytic enzymes, flushing action of urine, tears, etc., and normal flora
What is iL1s role as a defense mechanism?
it induces fever and attracts and activates phagocytes
Normal tissues with a ___ ___ ____ are a very _____ environment for bacteria.
good blood supply, hostile
What are killed bacterins made from?
bacteria grown in culture that are then killed
How is an autogenous bacterin made?
a bacterial isolate is obtained from a diseased herd, then the isolate was used to make a bacterin for immunization of new animals coming into the same herd
What organisms are difficult to make a bacterin from?
organisms that have capsules composed of polysaccharides or organisms with polysaccharide outer layers
What is used to make a modified live vaccine?
living organisms
What is the advantage of modified live vaccines?
living pathogens are more likely to express antigens that are important in a good immune response
What are the types of genetically engineered vaccines?
Gal E, Aro A, carrier
What are Gal E vaccines?
galactose epimerase-less mutants - cell wall deficient organisms that do not survive host immune responses well
What are Aro A vaccines?
aromatic pathway mutants - these organisms are unable to synthesize PABA and thus folic acid, and subsequently DNA
What is a carrier vaccine?
an avirulent organism into which genes for antigens of other bacteria or viruses have been cloned
What is a toxoid?
an immunizing product derived from a toxin whereby the toxic portion has been inactivated but the immunogenicity has been preserved