Biology of Infectious Agents Flashcards
muticellular community of bacteria attached to a surface, surrounded by a self-produced extracellular polymer matrix
biofilm
what percentage of microbial infections are caused by biofilm
60-80%
there are how many different species of oral biofilm (plaque)
> 600
what are free swimming bacteria called
planktonic
what is the definition when bacteria are irreversibly attacehed
sessile
what is surface conditioning
absorbtion of organic molecules onto a clean surface forming a conditioning film easy for bacteria to adhere/attach to
what is the name given to the 1st bacteria to attach to a conditioned surface
pioneer bacteria or primary colonizers
what bonds bacteria in reversible adhesion
van der waals forces
what bonds bacteria in irreversible adhesion
adhesion molecules (proteins)
secondary colonizers bind to ?
primary colonizers
fusobacterium nucleatum (F. nucleatum) has what purpose in biofilm formation
bridge species, meaning it bridges gap b/w early and late colonizers
what does cooperative consortia mean with regards to formation of biofilm
specific species of biofilm group together based upon their most important needs (ex. anearobic vs aerobic)
what volume percentage does the extracellular polymer make up vs. the actual bacteria in biofilm ?
polymer 75-95 %
bacteria 5-25 %
what are the 3 types of biofilm dispersal
active - enzyme degradation of extracellular polymer
passive - fluid flow causing movement, human intervention
new pioneer cells
what are the stages of the biofilm cycle
attachment, coloniization, growth, maturation, dispersal
REPEAT
What are 4 advantages of biofilm to microbes
- resistant to antimicrobials
- resistant to host defenses (WBC, phagocytes)
- resistant to mechanical removal
- use eachothers waste/resources for energy
what are the advantages of biofilm to the host
presence of good species of biofilm can prevent colonization of harmful species by
- occupying space
- producing defense molecules killing other species
adhesion molecules would be considered primary or secondary colonizers ?
primary colonizers
what is quorum sensing
process of cell-cell communication of bacteria measuring density of species w/in an environment
what is the purpose of quorum sensing
to synchronize behaviors that individual bacteria can’t perform alone
what stimulates light production by enzyme luciferase
when a threshold concentration of an inducer is reached
what is the signal molecule in gram negative bacteria
Acyl homoserine lactone (AHL)
what type of quorum sensing uses the same molecule for both a receeptor and regulater
Gram negative bacteria
T/F all quorum sensing is species specific
F
what is the signal molecule in gram positive quorum sensing
oligopeptide
what type of quorum sensing involves peptides leaving the cell then binding to a receptor and activating a downstream repsonse/regulatory gene
gram positive bacteria
what is the signal molecule used in quorum sensing of multiple species (non-species specific)
auto-inducer 2 (AI-2)
T/f Quorum sensing triggers 1 specific process for all bacteria
F, triggers many different responses
T/F Quorum sensing can trigger virulent genes liek toxins, proteases, and lysins
T
How could you inhibit biofilm formation
Block quorum sensing, cuz quorum sensing triggers biofilm formation
If you were to inhibit biofilm formation by inhibiting quorum sensing what would you attack ?
- signalling molecules
- receptors
