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8 Cards in this Set
- Front
- Back
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Describe the different stages of bacterial film formation!
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1) initial attachment of cells with pili to the surface - inert or living.
2) production of EPS (Exopolysaccharide) resulting in more firmly attachement. 3) development of biofilm, more EPS 4) maturation of biofilm, mushroom like structure, a tunnel through 5) dispersion of single cells from the biofilm (look for better nutrition places, flagella develops) |
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Describe briefly the pathogenesis of the cardiac valve biofilm formation!
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A) adherens of bacteria to the heart valves
B) microcolony formation by the bacteria C) maturation of the vegetation biofilm D) embolization of detached biofilm |
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Describe briefly a concept of development of biofilm on a medical implants! (kan komma på tent!!)
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A) planktonic bacteria can be cleared by host defenses (antibodies and phagocytic cells) and are susceptible to antibiotics
B) the adherent bacteria form a biofilm on the typically inert biomaterial surface, rendering them invisible to host defenses and protecting them from antibiotics C) phagocytic cells are attracted to the biofilms and attempt to engulf the biofilm but cannot. While the phagocytosis process has been frustrated, phagocytic enzymes are still released which damage the host tissue D) planktonic bacteria are released from the biofilm which can cause a spread of the infection to neighboring tissue |
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Describe the mechanisms of resistance to antimicrobial agents in biofilms! (kan komma på tent!)
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1) induction of the general stress response
2) increasing expression of multiple drug resistance (MDR) pumps (send antibiotics out of the bacteria) 3) activating quorum-sensing systems (more EPS) 4) changing profiles of outer membrane proteins (OMPs) |
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why are bacteria in the form of biofilms more resistant to Cell Mediated Immune system, Antibiotics and other environmental stresses?
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Bacteria in biofilms are much more resistant to lots of stresses because of the matrix of biofilm. Most of biofilms form an outer barrier by secreting extracellular polymeric materials, also called glycocalyx. This slimy layer blocks many stress factors such as chemicals, leukocytes, viruses and other predators.
Also, the rate of exchange of genetic materials between microorganisms in biofilm is about 600 times higher than those of in planctonic environment. Since many resistance genes are encoded in plasmids, frequency of genetic exchange is in proportion to the resistance to stresses. |
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What role does quorum sensing play in the formation of biofilms?
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Quorum sensing involves a density-dependent response/signal that initiates biofilm formations by the secretion of polysaccharide materials (EPS formation). It can also be linked to recruitment of other cells or even other types of organisms including prokaryotic-eukaryotic signaling
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Which statements about quorum sensing are true?
A) Quorum sensing occurs between individuals of the same species, but not between different species B) Quorum sensing allows microbial populations to respond to stimuli as a whole C) Quorum sensing controls expression of genes coding for virulence factors, antibiotic production and luminescence D) Interference with quorum sensing prevents biofilm formation |
B, C and D are correct
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What is quorum sensing?
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The use of secreted signaling molecules to regulate gene expression on a community level within and between bacterial species or between prokaryotes and eukaryotes
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