L4 Flashcards
(21 cards)
Plaque biofilm
Cooperating community of organisms with interbacterial and host-bacterial interactions
Stages of biofilm
Free swimming Attachment Growth Maturation Succession
Pellicle is made up of
Salivary glycoproteins
Antibodies
Bacteria after attachment
Synthesis of new outer membrane proteins
Active cellular growth
Co-Aggregation
Mediated by
Cell-Cell recognition of genetically distinct type in solution
Mediated by Protein/glycoprotein on one cell and carb on another
Co-adhesion
Cell-Cell Recognition of genetically distinct types when one is already adhering to surface
Influences on Co-adhesion
Temperature (none above 37 degrees)
Lactose (increase Lac decreases co-adhesion
Maturation involves
Replication
Metabolic partners
Firm attachment
Extracellular matrix
Primary colonizers
Mostly Gram (+) Streptococci
Secondary colonizers
Fusobacterium Nucleatum
Tertiary colonizers
Porphyromonas Gingivalis
Sources of matrix
Dead bacterial cells
Saliva
Gingival exudate
Gram POSITIVE matrix is very _____
Contains (2)
Fibrillar due to dextrans and levans
Bacteria near sulcular epithelium vs tooth attached
No interbacterial matrix
More spirochetes and flagellated bacteria
Robust biofilm in the presence of O2
Strep cristatus: factultative aerobe
Fusobacterium nucleatum: Anaerobe wants strep
Porphyromonas gingivalis: ob. anaerobe NEEDS coaggregation
Advantages of biofilm living
Defense
Protection from external changes
Transfer of information and genetic material
S. Cristatus can enter epithelial cells by
F. Nuc brings it in and this is dangerous because S.cristatus is gram (+)
Mechanisms for resistance
Biofilm bacteria grow more slowly
Exo-polymers retard diffusion (Ion exchange and enzymes that inactivate antibiotics)
Expression of different genes
Backbone of biofilm
Exopolysaccharides
Lower layer descrition
Tightly bound
Steep diffusion gradient
Polysaccharide matrix
Layers of biofilm
Lower Layer
Loose Layer
Fluid layer: nourishes biofilm by molecular diffusion
