microbiology

Question 1

plaque biofilm

Answer 1

organized cooperating community of organisms with specific inter-bacterial and host-bacterial interaction s

Question 2

biofilm attachment begins when ______________ adhere to acquired pellicle.

Answer 2

planktonic bacteria

Question 3

salivary pellicle consists of ____________ and ___________.

Answer 3

salivary glycoproteins, antibodies

Question 4

during the attachment phase of biofilm formation, _________ and __________ change within the pellicle.

Answer 4

surface charge and free energy

Question 5

________ attachers have specific attachment structures like fimbriae, extracellular polymenrs and glycocalyx.

Answer 5

rapid

Question 6

following attachment bacteria begin to _____________ and cellular growth becomes active.

Answer 6

synthesize new outer membrane proteins

Question 7

what is co-aggregation during biofilm growth phase?

Answer 7

cell-to-cell recognition of genetically distinct cell types; 2 distinct species are needed to interact, cells are suspended then form clumps which attach to pellicle

Question 8

what is co-adhesion during biofilm formation?

Answer 8

interactions between suspended and already adhering micro-organisms.

Question 9

what influences co-adhesion and what can modify it?

Answer 9

influenced by temperature (no co-adhesion at temps greater than 37degC) and lactose (increase lactose, decrease co-adhesion); modified by mouthwash, fluoride toothpaste, etc.

Question 10

during biofilm maturation, increase __________, _____ and _________.

Answer 10

replication and matrix formation, diversity and ecological succession

Question 11

primary colonizers bind to the ______________.

Answer 11

salivary pellicle

Question 12

T/F: primary colonizers can be both gr+ and gr-

Answer 12

True

Question 13

T/F: in general, no-mutan streptococci are associated with disease

Answer 13

False: ass with health

Question 14

example of secondary colonizer (bridge species).

Answer 14

fusobacterium nucleatum- prolific cooagregator

Question 15

T/F: pathogenic species are gr+ secondary colonizers

Answer 15

False, gr- tertiary colonziers

Question 16

when a biofilm increases in thickness, a _______ gradient develops, with completely anaerobic conditions in the deeper layers; while a ________ gradient develops as a result of bacterial metabolism

Answer 16

oxygen, reverse fermentation product

Question 17

What nourishes the supragingival plaque?

Answer 17

dietary products dissolved in the plaque

Question 18

What nourishes subgingival plaque?

Answer 18

periodontal tissues and blood (indirectly affected by diet)

Question 19

How does subgingival plaque get nutrients from tissues and blood?

Answer 19

bacterial hydrolytic enzymes breakdown host macro-molecules into peptides and amino acids

Question 20

what are 3 sources of baterial matrix?

Answer 20

dead bacterial cells, saliva, gingival exudate (JE fluid)

Question 21

what forms the backbone of biofilm?

Answer 21

exopolysaccharides

Question 22

the ______ layer of the biofilm contains a dense layer of microbes, polysaccharide matrix and steep diffusion gradients.

Answer 22

lower

Question 23

Why is mechanical therapy followed by antibiotics the best way to remove a biofilm-induced infection?

Answer 23

due to steep diffusion gradients of lower layer

Question 24

the _________ layer of biofilm is irregular in appearance and extends into surrounding medium

Answer 24

loose

Question 25

the ________ layer of biofilm is a stationary sublayer with a moving fluid layer and nourishes biofilm by molecular diffusion.

Answer 25

fluid

Question 26

the shape of supragingival plaque micro-colonies depends on __________.

Answer 26

shear force

Question 27

towers or mushroom micro-colony shape indicates ________.

Answer 27

low shear force

Question 28

elongated colonies capable of oscillation indicates a __________.

Answer 28

high shear force

Question 29

(supragingival) gr- interbacterial matrix is _________ due to dextrans and levans.

Answer 29

very fibrillar

Question 30

(supragingival) gr+ interbacterial matrix is ________ and contains ________ vesicles, filled with __________ and ________ and probably involved in _____________.

Answer 30

very regular, tri-laminar, endotoxins, proteolytic enzymes, adherence

Question 31

interbacterial carbs use _______ and ______ as energy sources.

Answer 31

dextrans, fructans

Question 32

In subgingival plaque, ________ forms primary attachment.

Answer 32

cuticle (unknown origin)

Question 33

in subgingival plaque, bacterial layers near sulcular epithelium do NOT have ________ and there are more _______ and ________ bacteria.

Answer 33

inter-bacterial matrix, spirochetes, flagellated