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BDS stage 2 > Microbiology for Dentists Theme 2 > Flashcards

Microbiology for Dentists Theme 2 Flashcards

1
Q

What is the autochthonous microbiotia ?

A

microorgansims characteristically found at a particular site

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2
Q

What is the allochthonous microbiotia ?

A

microorganims transiently present at a site

they dont thrive at the site but may colonise transiently if the site becomes compromised.

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3
Q

Where are archaea detected at increased levels ?

A

periodontal disease

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4
Q

What are the most common type of virus found in the mouth ?

A

bacteriophages

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5
Q

What is the most common viral pathogen in the mouth ?

A

HSV-1

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6
Q

Which viruses are asymptomatic in the mouth so care is needed for cross infection ?

A

hepatitis B and HIV

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7
Q

What is the most common fungus in the mouth ?

A

candida

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8
Q

What are the most abundant bacteria in the mouth ?

A

oral streptococci

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9
Q

What are the characteristics of oral streptococci ?

A

gram positive

alpha haemolytic

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10
Q

Which diseases are bacteria responsible for ?

A

caries
periodontitis
abcesses

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11
Q

What happens with oral streptococci and kiss plates ?

A

oral streptococci are alpha haemolytic - brownish colour change

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12
Q

What is alpha haemolysis ?

A

produces hydrogen peroxide which bleaches haemoglobin - Fe changes transition states from Fe3+ to Fe2+

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13
Q

How many species of bacteria naturally colonise the mouth ?

A

700 species- 13 phyla

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14
Q

How many of the species in the mouth can be cultured ?

A

50%

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15
Q

How long does it take to form mature dental plaque ?

A

1-4 minutes

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16
Q

Where do bacteria live in the mouth ?

A

tongue
cheek
palate
teeth

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17
Q

What are the lips, cheeks and palate like as a microbial habitat ?

A

have epithelial cells that are shed continually which get rid of bacteria

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18
Q

What is the tongue like as a microbial habitat ?

A

highly papillated which creates an anaeorbic environment

tongue is reservoir for obligate anaerobes

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19
Q

What are the teeth like as a microbial habitat ?

A

no shedding as no epithelial cell

prone to colonisation by bacteria

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20
Q

What is the enamel pellicle ?

A

a protein film between enamel and bacteria that supports and inhibits bacterial adhesion. Prevents enamel dissolution

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21
Q

Why do we culture microflora ?

A

understand physiology and biochemistry
link organism to disease
identify pathogenesis mechanisms
test antibiotics

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22
Q

How can it be hard to culture certain microflora ?

A

some bacteria are dormant - not easily reactivated

some species are fastidious

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23
Q

What are the culture independent methods of microbial analysis ?

A

PCR
Hybridisation
NGS- Metagenomics/targeted

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24
Q

What are holobionts ?

A

we are superorganisms of our on cells and microbiotia - act as one biological unit

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25
Q

Which streptococci are enriched in dental plaque compared to soft tissues ?

A

gordonii and sanguinis

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26
Q

Is saliva sterile ?

A

it is only sterile when secreted but accumulates with bacterial cells

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27
Q

Are there more bacteria attached to epithelial cells than there are free in saliva ?

A

more attached to epithelial cells

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28
Q

How are bacteria removed from oral surfaces ?

A

sloughing epithelial cell
mechanical debridement
active release

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29
Q

What is the problem with sampling saliva to look at the oral microbiome ?

A

there are different amounts of bacteria in the plaque compared to the soft tissue

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30
Q

What is the core microbiome ?

A

13 phyla present in almost everyone

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31
Q

What is the peripheral microbiome ?

A

species present in some and not others

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32
Q

Why do some microbiomes form clusters in different individuals ?

A

differences in the metabolome

this could be correlated with disease susceptibility

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33
Q

What does the acquired enamel pellicle do ?

A

it protects enamel

protects against the dissolution of enamel by keeping calcium and phosphate together

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34
Q

How does saliva help control plaque accumulation ?

A

aggregating bacteria which are then swallowed

having antimicrobial effects

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35
Q

Which salivary proteins bind to bacteria ?

A

MG2
Gp340
PRPs
Statherin

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36
Q

What are the roles of the salivary proteins ?

A

agglutinate
aggregate
inhibit
promote/inhibit microbial colonisation

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37
Q

What is aggregation/agglutination ?

A

occurs in the fluid phase
results in large clumps
large clumps removed in swallowing

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38
Q

What is adhesion ?

A

proteins in the saliva pellicle interact with bacteria resulting in the adhesion of bacteria to teeth

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39
Q

What is unique about salivary proteins ?

A

exhibit different bacteria binding proteins when in solution than on the surface

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40
Q

What are immunoglobulins present in saliva as ?

A

secretory IgA

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41
Q

What is the resting flow rate of IgA ?

A

33 mg/100 mL

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42
Q

What is the stimulated flow rate of IgA ?

A

6 mg/100 mL

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43
Q

What is the purpose of antibodies ?

A

to agglutinate bacteria - removed by swallowing

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44
Q

Which immunoglobulins are present in the GCF and what is their purpose ?

A

IgG and IgM

activate complement and opsinisation

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45
Q

What are examples of host receptors that bind bacteria ?

A

PRPs

Stahtherin

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46
Q

What are Proline rich proteins (PRPs) ?

A

they act in calcium phosphate stabilisation

found in high concentrations in parotid and submandibular saliva

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47
Q

Why are PRPs cyptitopes ?

A

they change conformation and reveal binding sites that bacteria want to bind to

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48
Q

What are the fucntional domains of PRPs and what do they do ?

A

N term- binds to Hydroxyapatite

C term binds to Actinomyces, Strep mutans and Sanguinis

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49
Q

What is statherin ?

A

main funcntion is calcium phosphate stabilisation
binds to hydroxyapatite and bacteria like actinomyces
secreted by parotid and submandibular glands

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50
Q

What does lysozyme do ?

A

cleaves bacterial cell walls

causes no enzymatic cell degradation

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51
Q

Where can you find lysozyme ?

A

tears
saliva
sweat

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52
Q

What is the downside of lysozyme ?

A

not equally effective against all bacteria

oral bacteria are more tolerant of it

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53
Q

What does lactoperoxidase do ?

A

catalyses the production of hypothiocynate from hydrogen peroxide ( by product of bacterial metabolism) and thiocyanate (in saliva)

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54
Q

What does hypothiocyanate do ?

A

uncharged so penetrates bacterial cell membranes

inhibits bacterial glycolysis

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55
Q

What does lactoferrin do ?

A

binds iron and makes it unavailable

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56
Q

What is the acquired enamel pellicle ?

A

protein film that forms on the surface of enamel
contains salivary glycoproteins and bacterial products
eg. PRPs which allow bacterial adhesion

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57
Q

Which tooth surfaces are available for colonisation ?

A

fissures
smooth surfaces
approximal
gingival crevice

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58
Q

Is supragingival plaque aerobic or anaerobic ?

A

aerobix

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59
Q

Where is supragingival plaque present ?

A

in health on the teeth

in cracks and fissures it can leads to caries

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60
Q

What is the nutrient source of supragingival plaque ?

A

saliva

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61
Q

Is subginigival plaque aerobic or anaerobic ?

A

anaerobic

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62
Q

What are significant amounts of subgingival plaque associated with ?

A

periodontitis

ginigivitis

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63
Q

What is the nutrient source of subgingival plaque ?

A

gingival crevicular fluid

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64
Q

When does plaque accumulate faster ?

A

day

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65
Q

Where do pioneer colonisers attach to ?

A

salivary pellicle

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66
Q

What are environmental factors affecting plaque formation ?

A

diet

smoking

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67
Q

What are bacterial factors affecting plaque formation ?

A

co aggregation

bacterial adhesins that recognise the pellicle

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68
Q

What is the cyclic nature of plaque build up ?

A

initial colonisation- Streptococcus, Actinomyces, Veillonella
Microflora alteration phase- Fusobacterium and Prevotella
Lack of cleaning leads to dental caries and periodontitis

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69
Q

What is the role of the acquired enamel pellicle ?

A

primary colonising bacteria in plaque attach to it

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70
Q

What are the characteristics of the acquired enamel pellicle ?

A 
1-3 micrometres thick 
can permeate the outer layer of enamel 
not easily removed 
present on most enamel surfaces
a deposit of saliva proteins
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71
Q

How is the enamel pellicle formed ?

A

by the preceipitation of denatured saliva proteins

it is selective- proteins with a high binding affinity bind to the tooth surface

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72
Q

As well as saliva proteins what else does the pellicle contain ?

A

components of the GCF

oral mucosa and microbial cells

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73
Q

What are the functions of the enamel pellicle ?

A

lubricant
reduces mobility of calcium and phosphate ions - this stops the dissolution of enamel - demineralisation
prevents inappropriate crystal growth- stops dental calculus
contains enzymes

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74
Q

What is within the pellicle which prevents inappropriate crystal growth ?

A

statherin and PRPs

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75
Q

Which active enzymes are within the pellicle ?

A 
amylase
lysozyme 
peroxidase 
carbonic anhydrase 
glucosyltransferase
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76
Q

What does the pellicle do with bacteria ?

A

can inhibit and be a substrate for bacterial adhesion

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77
Q

What is within the pellicle that allows bacteria to adherer ?

A

the salivary proteins have receptors for bacteria

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78
Q

Name some salivary proteins in the pellicle ?

A 
MGI
Amylase
PRPs
Statherin 
Gp340
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79
Q

Which bacteria are present in initial plaque ?

A

50% of bacteria in initial plaque are streptococci

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80
Q

What are the human oral streptococci groups ?

A

mitis
anginosis
salivarius
mutans

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81
Q

What is the mitis streptococcus group ?

A

the most numerous in the mouth

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82
Q

What is the anginosis streptococcus group ?

A

commensal but found at abcesses

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83
Q

What is the salivarius streptococcus group ?

A

generally commensal but also used as probiotics

also found elevated in dental caries

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84
Q

What is the mutans streptococcus group ?

A

associated with dental caries

found in mature plaque and is not an early coloniser

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85
Q

What is the most abundant bacterium in initial plaque ?

A

Streptococcus Oralis

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86
Q

What are streptococcal adhesins ?

A

they are proteins on the surface of oral streptococci that can adhere to receptors on salivary proteins in the pellicle

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87
Q

What is an example of a streptococcal adhesin ?

A

antigen I/II

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88
Q

What is antigen I/II ?

A

a large multi domain protein on the surface of oral streptococci
mediates adhesion to the gp340 salivary agglutinin protein in the pellicle

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89
Q

What are the other functions of antigen I/II ?

A

can bind to to other bacteria like actinomyces

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90
Q

What structural properties allow antigen I/II to bind to other bacteria ?

A

it has a C-motif that covalently binds to peptidoglycan

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91
Q

What are the pioneer coloniser species ?

A

actinomyces

veillonella

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92
Q

What are actinomyces ?

A

gram positive pleimorphic rods
facultative anerobes
harmless but can cause disease

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93
Q

What are veilonella ?

A

gram negative cocci
strict anaerobes
feed on lactate produced by other oral bacteria

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94
Q

Does veilonella cause disease ?

A

not associated with disease but elevated in caries

found in supraginigival plaque although its aerobic

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95
Q

How does veilonella survive in supragingival plaque if its anaerobic ?

A

the surrounding aerobic bacteria use the oxygen so that the environment becomes anaerobic

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96
Q

What is the process of dental plaque formation ?

A 
adhesion to the surface 
coaggregation 
coadhesion 
mature biofilm with matrix 
dispersal
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97
Q

What is the appearance of mature supragingival plaque ?

A

stratified

gram positive cocci and short rods a tooth surface with filament towards the outer layers

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98
Q

What does supragingival mature plaque cause ?

A

causes a shift towards acidogenic/aciduric bacteria

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99
Q

Does the amount of plaque correlate with dental caries ?

A

no evidence to support correlation

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100
Q

What does accumulation of plaque at the gum line cause ?

A

irritates tissues and can lead to calculus formation
this leads to gingivitis (reversible)
can progress to periodontitis (irreversible)
accompanied with a change in oral microbiotia

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101
Q

What is present in the subgingival crevice in the mouth ?

A

few bacteria
anaerobic bacteria- not found elsewhere
asacchrolytic, proteolytic bacteria found here

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102
Q

What do early colonisers support the attachment of ?

A

bridging organsims

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103
Q

What are bridging organisms ?

A

they stick to perio pathogens and trigger inflammation of the gingiva

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104
Q

What is an example of a bridging organism ?

A

fusobacterium nucleatum

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105
Q

What is fusobacterium nucleatum ?

A

gram negative
proteolytic
anaerobic
long rods

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106
Q

What does fusobacterium nucleatum do ?

A

forms co aggregates with early coloniseres and later colonisers
invades host epithelial cells
present in high numbers in subgingival plaque

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107
Q

What is supragingival calculus a deposit of ?

A

saliva

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108
Q

What is subgingival calculus a deposit of ?

A

serum

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109
Q

What does the rough surface of calculus do ?

A

trigger inflammation

leading to gingivitis and periodontitis

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110
Q

Where does calculus form ?

A

near salivary duct opening

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111
Q

What is calculus ?

A

mineralised plaque

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112
Q

What are sialoliths ?

A

form in salivary ducts

they are supersaturated Calcium phosphate

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113
Q

What are the mechanisms of enamel loss ?

A

fracture
caries
erosion
abrasion

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114
Q

What is caries ?

A

loss of enamel due to bacterial acid production

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115
Q

What is erosion ?

A

loss of enamel due to dietary acids

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116
Q

What is abrasion ?

A

loss of enamel due to mechanical wear

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117
Q

What is the main component of enamel ?

A

biological appatite

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118
Q

What is biological appatite made from ?

A

Ca
Phosphate
hydroxyl ions

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119
Q

Is biological appatite soluble ?

A

sparingly soluble

increased solubility at low pH

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120
Q

What happens to pH after a sugar rinse according to stephans curve ?

A

there is a drop in pH

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121
Q

What happens after the drop in pH ?

A

after the decrease in pH the pH tries to return to normal

this is the time in which the enamel dissolved as it is exposed to a low pH

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122
Q

What is the critical pH ?

A

roughly 5.5

this is the pH which under the enamel dissolves quicker

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123
Q

What happens if you rip water on enamel ?

A

enamel will eventually dissolve
an equilibrium isnt reached as water is always being replaced
fresh water doesnt have any calcium in it - calcium always leaving the tooth

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124
Q

Why doesnt saliva dissolve enamel ?

A

supersaturated calcium phosphate doesnt come into contact with the enamel as the statherin and PRPs bind to the ions maintaining the enamel

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125
Q

How do you calculate the solubility product ?

A

the ion concentrations multiplied

the ion concentrations must be multiplied by their respective power

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126
Q

What is the ionic product ?

A

the same as the solubility product but in solution

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127
Q

If IP>SP ?

A

solution is supersaturated

unless the ions are stabilised in some way like by stahterin etc

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128
Q

What if SP >IP ?

A

solution is unsaturated and you get dissolution

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129
Q

What are the 2 ways that calcium hydroxyapatite can dissolve ?

A

loss of hydroxide ions

loss of phosphate ions

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130
Q

What happens with the loss of hydroxide ions ?

A

adding acid means hydroxyapatite dissolves phosphate and hydroxyl ions
increasing acid means hydroxyl ions must decrease - pulling out hydroxyl ions to maintain equilibrium

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131
Q

What happens with the loss of phosphate ions ?

A

hydrogen ions bind to phosphate ions - pulling out phosphate ions
IP drops and SP is higher - dissolution

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132
Q

What is the effect on the critical pH if someone has lower calcium and phosphate concentrations ?

A

leads to a higher critical pH of about 6.5- this means there is a greater range of pH over which dissolution can occur

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133
Q

The KSP of a sparingly soluble halids is 4x10^8 moles

How many moles of each element will dissolve in a litre of water ?

A

square root
solubility product is the product of the ion concentrations.
2x10^4

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134
Q

in the global burden of diseases which is the most 2nd prevalent disease ?

A

Latent tuberculosis

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135
Q

What is the name for the total genetic information in a complex population ?

A

metagenome

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136
Q

Which of the following species is most strongly acidogenic ?

A

lactobacillus fermentum

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137
Q

The concept that the total amount of plaque is responsible for dental caries is ?

A

specific plaque hypothesis

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138
Q

Which of the following species belongs to the mutans group streptococci ?

A

Streptococcus Sobrinus

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139
Q

At the crtical pH of enamel what is the relationship of the KP to IP ?

A

KP=IP

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140
Q

In acidic conditions hydroxyapatite dissolves because ions are removed from solution. Which ions are likely to be removed ?

A

Hydroxide

phosphate

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141
Q

What are the different types of caries ?

A 
primary 
secondary 
residual 
active v inactive 
early childhood caries
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142
Q

What is early childhood caries ?

A

presence of one or more decayed missing or filled tooth surfaces in any primary tooth between birth and 71 months

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143
Q

Which type of caries are becoming prominent ?

A

occlusal, interproximal and EDJ caries ever since the late 19th century

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144
Q

Why is caries set to increase in global prevalence ?

A

greater longevity and population growth

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145
Q

Which bacteria are commonly acossiated with caries ?

A

mutans streptococci
lactobacillus
actinomyces
bifidobacterium - scardovia wigiassae

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146
Q

How are the streptococci broken up ?

A

broken into groups with each group containing differnt species

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147
Q

What bacteria does the mutans group contain ?

A

strep mutans

strep sobrinus

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148
Q

What are the features of the mutans streptococci ?

A

gram positive
catalase negative
sacchrolytic
facultative anaerobes

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149
Q

What are the caries associated with streptococci ?

A

S mutans
S sobrinus
non mutans acossaited low pH streptococci

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150
Q

What are the characteristics of S mutans ?

A

acidogenic
aciduric
produces glucans from sucrose

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151
Q

What is different about S.Sobrinus comapred to S.mutans ?

A

more acidogenic

more adherent

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152
Q

Why does Kochs postulates not match up with Strep mutans ?

A

organism must be present in all cases of disease and not in healthy individuals- this cannot be the case because strep mutans is in 96% of the population and the level rather than the presence is important

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153
Q

Which bacteria are acossiated with early childhood caries ?

A

bifidobacterium
scardovia wiggisae
they have been isolated on acid agar

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154
Q

What are the characteristics of Scardovia Wiggisiae ?

A

anaerobic
pleomorphic
gram positive bacilli
sacchrolytic - produces acetic and lactic acid

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155
Q

What is the problem with S mutans ?

A

it has a low predictive value- there are other species like Prevotella that have a higher predictive value

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156
Q

What are germfree animals ?

A

no microorganism present in them

used to investigate microbial aetiology

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157
Q

What are examples of virulence factors ?

A

adhesins
acid production
aciduricity

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158
Q

What are examples of adhesins ?

A

antigen I/II
glucosyltransferases
aciduricity

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159
Q

How do bacteria remain aciduric ?

A

DNA repair proteins

protective membrane proteins

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160
Q

How are carbohydrates utilised by bacteria ?

A

glucose and sucrose make acid and intracellular storage polymers
sucrose also makes exopolysaccharides

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161
Q

How do bacteria uptake sugar ?

A

polysaccharides are digested

monosaccharides and disaccharides are imported

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162
Q

What is xylitol ?

A

a sugar substitute

imported, metabolised and knocked out - futile cycle

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163
Q

How is glucose uptake described ?

A

constitutive

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164
Q

What happens in high sugar conditions ?

A

lactate is the major product
homolactic fermentation
intracellular polysaccharides are made

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165
Q

What happens in low sugar conditions ?

A

mixed acid fermentation - heterofermentation
lactate dehydrogenase is inhivited
Intracellular polysacchrides are digested

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166
Q

Why is oxygen important in fermentation ?

A

it is an important regulator

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167
Q

What are intracellular polysaccharides ?

A

produced via glucose 1 phosphate when carbohydrates are in excess
make a glycogen type glucan
they are broken down and used for glycolysis in starvation

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168
Q

How do you get greater acid tolerance ?

A

pre acidification results in greater acid tolerance

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169
Q

What are mechanisms of acid adaptation ?

A

reduced permeability of cell membrane to protons
induction of proton translocating ATPase
induction of alkali production systems
induction of stress proteins

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170
Q

What are the purpose of stress proteins ?

A

protect enzymes and nucleic acids from denaturation

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171
Q

What alkali systems are higher in caries free subjects ?

A

salivary arginine deaminase

urease

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172
Q

What do strep gordonii and strep sanguinis do with urease ?

A

arginine breaks down to urea by arginase

urea broken down to carbon dioxide and ammonia bu urease

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173
Q

What do strep salivarius and actinomyces do with arginine deaminase ?

A

arginine broken down citrulline releasing ammonia

citrulline enters the carbomoyl phosphate cycle releeasing ammonia

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174
Q

What are the macromolecules that form the basic structure of the matrix ?

A

polysaccharides
proteins
nucleic acids

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175
Q

What do the macromolecules do ?

A

form a scaffolding

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176
Q

What are the small molecules that are trapped in the matrix ?

A

nutrients
signalling molecules
trace metals

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177
Q

What are exopolysaccharides ?

A

polymers made of sugar residues that are secreted by a microorganism into the environement

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178
Q

What are the 2 types of exopolysaccharides ?

A

glucans and fructans

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179
Q

What are glucans made by ?

A

glucosyltransferase

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180
Q

What are fructans made by ?

A

fructosyltransferases

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181
Q

What are glucans ?

A

polymer of glucose formed outside the cell using sucrose as the substrate

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182
Q

Why is sucrose the substrate for glucan synthesis ?

A

contains a high energy glycosidic bond

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183
Q

What are 2 examples of fructan polymers ?

A

inulins and levans

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184
Q

What are inulins ?

A

insoluble
contain beta 2,1 bonds
can be cross linked with beta 2,6 bonds
identical to a fructose polymer in vegetables- used as a long term carbohydrate storage rather than starch

185
Q

Who synthesises inulins ?

A

streptococcus mutans

steptoccus salivarius

186
Q

What are levans ?

A

contain beta 2,6 bonds
water soluble
rotate polarised light to the left

187
Q

Who makes levans ?

A

strep sanguinis
strep salivarius
strep sobrinus

188
Q

What are the 2 examples of glucan polymers ?

A

mutans and dextrans

189
Q

What is mutan ?

A

water insoluble
core is alpha 1-3 linked
70% of plaque exopolysaccharide is mutan
some can be mostly alpha 1-3 linked but with some alpah 1-6 links

190
Q

What is dextran ?

A 
soluble 
almost all alpha 1-6 bonds 
rotates polarised light to the right 
synthesised by strep salivarius 
many variations with alpha 1-3 linked glucose side chains
191
Q

How do enzymes form glucans and fructans ?

A

enzymes make alpha 1,3 and alpha 1.6 links

192
Q

What is special about enzymes that make glucans and fructans ?

A

they dont need a primer

can add to preexisting glucan which induces a conformational change

193
Q

How are GTFs made and secreted ?

A

they are secreted into plaque and are extracellular

different bacteria secrete different enzymes

194
Q

What do glucans act as ?

A

receptros for unrelated GTFs

195
Q

What are the other enzymes present in the matrix ?

A

proteases

dextrinases

196
Q

What are some examples of GTFs ?

A

glucansucrase
dextransucrase
mutansucrase

197
Q

What are some examples of FTFs?

A

fructansucrase
inuslosucrase
levansucrase

198
Q

What does GTF-S cleave ?

A

water soluble dextran like glucans with an alpha 1-6 backbone

199
Q

What does GTF-I cleave ?

A

insoluble glucans with alpha 1-3 backbone

200
Q

What does GTF-SI cleave ?

A

partially soluble alpha 1-3 polymer

201
Q

Which gene codes for GTF-I ?

A

gtfB

202
Q

Which gene codes for GTF-SI ?

A

gtfC

203
Q

Which gene codes for GTF-S ?

A

gtfD

204
Q

How many types of FTFs are there ?

A

2- one synthesis an inulin like polymer and the other a levan

205
Q

Which bacteria make fructans ?

A

strep mutans

strep salivarius

206
Q

What is mutan essential for ?

A

strep mutans biofilms

207
Q

Which sugar produces a thicker biofilm matrix ?

A

bacteria grown in glucose produce a thicker matrix and bacteria grown in sucrose thicker matrix

208
Q

What can mutanase potentially do ?

A

treatment with mutanase can potentially reduce biofilm formation

209
Q

What will knocking out genes like gtfB do ?

A

reduce biofilm formation - thin biofilms

210
Q

What do biofilms do with microcolonies ?

A

biofilms form mutan rich colonies- clusters of polysaccharides that have a low pH - acid is localised to certain areas- enamel degradation

211
Q

What happens if you add sucrose to a culture of bacterial cells ?

A

the bacterial cells will clump as they will use sucrose to make glucans
bacteria have glucan binding proteins on the surface
aggregate

212
Q

How are FTFs related to caries aetiology ?

A

FTFs are very active in plaque
however the amount of fructan in plaque is low
suggests that fructan is turned over rapidly and then used quickly as a short term energy store

213
Q

How are FTFs thought to contribute to caries ?

A

they extend the fermentation time on plaque bacteria

214
Q

What do glucans do with mutans streptococci ?

A

they help them to stick

215
Q

What do soluble dextrans mediate ?

A

cell aggregation

216
Q

What do insoluble glucans contribute to ?

A

cell adherence

217
Q

How do other bacteria adhere to strep mutans ?

A

via glucan ridges

218
Q

Which interactions do glucan bridges lead to ?

A

metabolite cycling
signalling
competition

219
Q

What are amyloids ?

A

proteins that form robust fibrils that are hard to degrade

they run perpendicular to the length of the fibril

220
Q

What are fucntional amyloids ?

A

have a function in biofilm stabiliisation
melanin formation
innate antiviral immune response

221
Q

Which bacteria produce large amiunts of the extracellualr DNA ?

A

p.Aureginosa

222
Q

What does treatment with DNase lead to ?

A

disrupts biofilms temporarily

can reduce periodontal pathogen colonisation

223
Q

What re the functions of extracellular DNA ?

A 
gene transfer
chelates metal ions 
biofilm formation 
antimicrobial protection 
nutrient uptake 
biofilm stability
224
Q

What is plaque fluid ?

A

the fluid which fills spaces between bacteria in dental plaque

225
Q

How much is the plaque fluid ?

A

30% of total plaque volume

226
Q

What is the composition of plaque fluid ?

A

modified saliva
bacterial metabolites
gingival fluid

227
Q

What is the function of the plaque fluid ?

A

acts as a buffer between saliva and tooth
maintains calcium, phosphate ans fluoride concentrations
can retain antimicrobials in tooth wash

228
Q

What is periodontitis ?

A

spectrum of diseases

affects tooth supporting structures

229
Q

What happens to the junctional epithelium in periodontitis ?

A

junctional epithelium at base of gingival crevice migrates down root of tooth to form periodontal pocket

230
Q

Migration of the junctional epithelium is a result of ?

A

direct microbial action but also a result of exaggerated host immune response

231
Q

Changes in the microbiotia lead to ?

A

changes in the environmental conditions

232
Q

What is the size of deep pockets ?

A

5mm +

233
Q

What can recession be to the extent of ?

A

apical third of the tooth

234
Q

What are some manifestations of periodontitis ?

A

loss of periodontal bone support
mobility
tooth loss
triangular shaped boe defects- intrabony periodontal pocket

235
Q

What are some factors influencing periodontal disease ?

A 
tobacco
oral hygeine 
medication 
type 2 diabetes 
stress
systemic
236
Q

What is the development of periodontal disease ?

A

initial microbial homeostasis
change in environment leads to altered microbial population
exaggerated inflammatory response
damage to periodontium

237
Q

What is the cementum colonised by ?

A

gram positive species like actinomyces and streps- early colonisers
bridging organisms- fusobactrium nucleatum allow microbial organisms to attach
environmental change can lead to co-aggregation and co-adhesion

238
Q

What is microbial dysbiosis ?

A

conditions changing mean shift in bacteria becoming pathogenic - disease promoting microbiotia

239
Q

Besides microbial dysbiosis what is also important in periodontits ?

A

hyper inflammatory host response

individual patient

240
Q

What type of microbiotia promotes periodontitis ?

A

synergistic
dysbiotic
shape the disease provoking microbiotia

241
Q

Describe the microbial changes in periodontal disease ?

A 
disordered collection 
aggregation
interspecies interactions 
structured heterogenic communties 
keystone pathogens 
dysbiosis 
expression of virulence factors
242
Q

How can we determine the subgingival microbiota ?

A

direct sampling from perio pockets
cultivation of samples
molecular techniques

243
Q

What is the problem with trying to determine the species in subgingival plaque ?

A

most perio pathogens are anaerobic- when exposed to air cant culture

244
Q

What is checkerboard hybridisation ?

A

DNA probes made for existing bacterial sequences
DNA taken from host and purified
probes used to identify which species are present

245
Q

What does the intensity of the signal correlate with ?

A

the amount of organism

semi quantatative

246
Q

What is the red complex ?

A

frequently associated with severe periodontal disease

247
Q

What are the 3 organisms of the red complex ?

A

Porphyromonas.gingivalis
Tannerela.forsytha
Trepnoma.denticola

248
Q

Which organisms are the initial colonisers in periodontal disease ?

A

Streptococcus- commensal

249
Q

Which organisms are bridging organisms ?

A

fusobacterium nucleatum

250
Q

What are the characteristics of F. Nucleatum ?

A

gram negative
proteolytic
anaerobic
long rod shaped

251
Q

What does F . nucleatum do ?

A

forms co-aggregates
with early colonisers- strep
late colonisers- T. denticola
inavdes host epithelial cells

252
Q

What are the characteristics of red complex bacteria ?

A

gram negative
proteolytic - destroy proteins in GCF
fastidious anaerobe

253
Q

What is Porphyromonas gingivalis ?

A 
short rods
produces black/brown pigments using iron 
highly proteolytic 
adheres to oral streptococci 
keystone
254
Q

What are keystone pathogens ?

A

disproprotionately important role in causing disease

255
Q

What is tannerella forsytha ?

A

short rods tapered
difficult to grow in monoculture
possess a glycosylated S layer- hide from immune system

256
Q

Why doesnt Kochs postulates apply to periodontitis ?

A

not culturable
not present in all cases of disease
more than 1 species involved
level rather than presence more important

257
Q

What is the TM7 phlyum ?

A

frequently detected in subgingival dental plaque
elevated in mild perio
can grow when co-cultured- actinomyces odontlyctus
small genome- reflects dependence on others for growth

258
Q

What are the adhesins of P.gingivalis ?

A

major fimbriae- adhesion and invasion

minor fimriae- coaggregation

259
Q

What does the P.gingivalis capsule do ?

A

allows them to evade host immunity - phagocytosis and complement activation

260
Q

What does the LPS of P.gingivalis do ?

A

it is potently inflammatory

261
Q

What do P.gingivalis proteases do ?

A

extracellualr cysteine proteases-
cleave host proteins and collagens
major antigen in infection

262
Q

What are the functions of Extracellular cysteine proteases ?

A

nutrition
processing
haemogluttinin
adhesion

263
Q

What is AA ?

A

exception to the ecological plaque hypothesis
aggressive forms of periodontitis
facultative anaerobe

264
Q

What is the function of AA ?

A

adhesion
impairment of host defence
tissue invasion
bone resorption

265
Q

What is the function of AA adhesins ?

A

tight adherence by fimbriae and locii

bind to epithelial cells and enhance receptor medaited endocytosis

266
Q

What are leukotoxins ?

A

pore forming toxin

targets immune cells expressing B2-integrin

267
Q

What other AA toxins are there ?

A

cytolethal distending toxin

268
Q

What is AA JP2 ?

A

clone associated with aggressive forms of periodontitis
storng leuukotixin activity
W.african adolescents

269
Q

Are fungi eukaryotic or rokaryotic ?

A

eukaryotic

270
Q

What are ascomycota ?

A

they can form ascospores

candida doesnt even though it is part of the ascomycota

271
Q

What are basidiomycota ?

A

can cause disease - cryptococcus

272
Q

What is the morphology of fungi ?

A

they grow as branched tubes called hyphae

273
Q

What is the relative size of fungi ?

A

they are smaller than human cells but bigger than bacteria

274
Q

What is the structure of the fungi cell wall ?

A

thick rigid cell wall
made of ergesterol rather than cholesterol
divided into 2 layers

275
Q

What is the outer layer of the fungi cell wall like ?

A

amorphous
glycoproteins
carbohydrates
mannans

276
Q

What is the inner layer of the fungi cell wall like ?

A

glucans and chitin

277
Q

Why is the fungi cell wall important ?

A

for adherence and antigenicity

278
Q

What is the carriage rate of candida ?

A

35-55%

279
Q

What is the most common fungi species in the mouth ?

A

fungi

280
Q

What are some members of the genus candida ?

A 
candida albicans 
candida glaborata 
candida kruvei 
candida tropicalis 
candida dublineisis
281
Q

Is the genus candida pathogenic ?

A

most non pathogenic

282
Q

What does it mean if candida are dimorphic ?

A

they can transition between yeast and hyphal form

283
Q

What is the significance of hyphae ?

A

they can be disease causing and invade epithelium

284
Q

What does it mean if candida is opportunsitic ?

A

change in the environment

change in the gene expression and expression of virulence factors

285
Q

What is the process of candida becoming pathogenic ?

A

normal commensals
change in environemntal conditions
candida proliferation
pathogenic and disease

286
Q

What are the different morphologies of candida ?

A

hyphae
budding yeast
pseudohyphae and chlamydosphore

287
Q

What is morphotype switching ?

A

swich between yeast and hyphal form

288
Q

What is morphotype switching controlled by ?

A 
osmotic shock 
temperature fluctuations
pH 
nutrients 
oral bacteria
salivary factors- statherin
289
Q

Where can you find candida ?

A

in mixed species biofilms

amongst cocci and roda

290
Q

How can bacteria influence candida ?

A

presence of bacteria can influence how they switch from hyphae to yeast
serum triggeres hyphae profuction
peptidoglycan can trigger hyphal formarion

291
Q

How can Strep Gordonii influence hyphae ?

A

strep gordonii antigen I/II mediate binding to C.Albicans hyphae

292
Q

How does Strep mutans influence hyphae ?

A

produces competence stimulating peptide which inhibits C.Albicans hyhae formation

293
Q

What is competence stimulating peptide ?

A

allow transformation and DNA transfer

294
Q

What type of relationships do oral bacteria have with C.Albicans ?

A

synergistic or competitive

295
Q

Overall do Oral streptococci benefit or inhibit C.Albicans ?

A

benefit

296
Q

Does lactobacillus inhibit or benefit oral bacteria ?

A

inhibit

297
Q

What type of agar is Candida grown on ?

A

Sobarand dextrose agar

selects agaisnt bacteria due to low pH

298
Q

Which candida species have true hyphae ?

A

albicans

dublineisis

299
Q

Which differential agar is candida grown on ?

A

CHROMagar

different species have different morphologies

300
Q

How else can we identify Candida species ?

A

using different carbohydrates

diff species have diff nutritional requirements

301
Q

What are the virulence factors of candida ?

A 
adherence 
morphology 
phenotype switching 
hydrolytic enzymes
candidalysin
302
Q

How does adherence work as a candida virulence factor ?

A

candida can adhere to epithelium or prostheses and resist saliva flow
produce adhesins

303
Q

Which adhesins do candida produce ?

A

mannoproteins
fibrils
agglutinin like sequence proteins
hyphal wall protein

304
Q

How does morphology act as a candida virulence factor ?

A

polymorphic/dimorphic
hyphae formation allows
oral epithelium invasion
evade pahgocytosis

305
Q

Which factors are hyphae produced in response to ?

A

temperature
carbon dioxide
alkaline pH

306
Q

How does phenotypic switching act as a candida virulence factor ?

A

change morphology in response to environmental stimuli

influence antigenicity, adhesion and drug susceptibility

307
Q

Which hydrolytic enzymes do Candida produce ?

A

Aspartyl proteinases

phospholipases

308
Q

What do aspartyl proteinases do ?

A 
nutrtion 
cell morphology siwtching 
remove tissue barriers
cleave immune proteins
facilitate adherence
309
Q

What do phsopholipases do ?

A

hydrolyse phospholipids leading to host cell membrnae damage
cell lysis
receptor exposure

310
Q

What is candidalysin >

A

a lytic peptide that punches holes in epithelial cell

allows penetration of host tissue

311
Q

What are some manifestations of candidasis ?

A

denture stomatitis
biofilm formation on surface of dentures
damage arises due to hyphal formation
neutrophil damage

312
Q

What are some local factors that can make patients predisposed to candidasis ?

A

dentures
inhaled corticosteroid inhalers
reduced salivary formation
rich carb diet

313
Q

What are some systemic factors that can make patients predisposed to candidasis ?

A 
medication
diabetes
nutritional deficiency 
salivary gland hypofunction 
HIV
age extermities
314
Q

How can we diagnose oral candidosis ?

A

appearance- erethrema, white patches

lab tests- blood tests, oral swab, biopsy and histology

315
Q

What are the primary forms of oral candidosis ?

A

acute pseudomembreanous candidosis
acute erythemous candidosis
chronic erythemous candidosis
chronic hyperplastic candidosis

316
Q

What is acute pseudmembranous candidosis ?

A

red mucosa
plaques can be scraped off hard palate and tongue
inhaler use

317
Q

What is acute eryhtemous candidosis >

A 
painful red patches
cracking of dorsum 
loss of filiform papillae 
due to antiobiotic sore mouth 
antibiotic use removes bacteria but leads to candida overgrowth
318
Q

What is chronic erythemous candidosis ?

A

denture stomatitis
poorly fitting denture
no hyphae invasion
lack of OH

319
Q

What are the treatment methods for denture stomatitis ?

A

wash dentures in chlorhexidine/sodium hypochlorite

leave dentures out as much as possible

320
Q

What is chronic hyperplastic candidosis ?

A 
candidal leukoplakia on sides of mouth 
heavy smokers 
can progress to malignancy 
cant be scraped off 
candidal hyphae invade epithelial layer
321
Q

What are parasites ?

A

eukaryotic pathogens

322
Q

Which parasites are part of the excavata group ?

A

leismania

trichomonas tenax

323
Q

Which parasites are part of the amoebozoa ?

A

entamoeba gingivalis

324
Q

What is symbiosis ?

A

association between organisms from different species

325
Q

What is mutualism ?

A

both partners benefit from interaction and are co-dependent for thriving

326
Q

What is commensalism ?

A

one partner benefits whereas the other is neither harmed nor receives benefit

327
Q

What is parasitism ?

A

one partner relies on the host for nutrients and shelter at cost to the host and leads to host damage

328
Q

What are obligate symbionts ?

A

can only live together in symbiosis
highly adapted to body sites in one host
most parasitic protozoa are obligate symbionts and require a host to complete their life cycle

329
Q

What are facultative pathogens ?

A

they dont cause disease all the time

330
Q

What are opportunstic pathogens ?

A

cause pathologies when the host is compromised

331
Q

In which situations can the host be compromised ?

A

AIDS
immunodeficinecy
malnutrition
chemotherapy

332
Q

Which are the best adapted parasites ?

A

the ones that are least pathogenic and dont harm their host

333
Q

Which 2 functions must the mucosa mediate ?

A

protect the individual from insults- microbial, chemical and physical
facilitate exchange

334
Q

Which interactions are required for healthy mucosa ?

A

microbes interact with epithelial cells and with immune cells

335
Q

What are supraorganisms ?

A

interactions between human and microbial cells

336
Q

What is a eubiotic microbiotia ?

A

promotes health

337
Q

What is a dysbiotic microbotia ?

A

promotes diseases
abnormal, micorbial and taxonomic structures lead to pathologies
even in the absence of pathogens

338
Q

What are pathobionts ?

A

members of the microbiotia that have the potential to cause damage

339
Q

What does monexenous mean ?

A

parasite requires a single host for life cycle completion
T.tenax
E.gingivalis

340
Q

What does heteroxenous mean ?

A

two or more hosts required for completion
1 host is intermediate for development other is definite for sexual development
Leishmania

341
Q

What does promiscuous mean ?

A

infect broad range of hosts

T.tenax

342
Q

What are zoonoses ?

A

human disease caused by animal parasites

animals are reservoirs for human pathogens

343
Q

Which archaea are in the oral cavity ?

A

methanobrevibacter

344
Q

Which microbial eukaryotes are present in the oral cavity ?

A

fungi

microbial parasites- T.tenx/E.gingivalis

345
Q

What are autochtnous microbiotia >

A

characteristically found at a particular site
adapted to grow in the cavity
T.tenax and E.gingivalis

346
Q

What are allocthnous micrbiota ?

A

transiently present due to host compromise

347
Q

What is the route of transmission of Leishmania ?

A

sand flies

348
Q

What are the 3 main pathobiologies of Leishmania ?

A

cutaneous leishmania- most common. skin lesions etc
visceral leishmania- fever, weight loss, spleen and liver
mucocutaeneous leishmania- destruction of mucous membranes- requires nose, mouth entry

349
Q

What are 2 common microbial eukaroyotes assocaited with periodontitis ?

A

T.tenax

E.gingivalis

350
Q

What are the types of Trichmonas ?

A

Trichomonas vaginalis
trichomonas gallinae
trichomonas tenax

351
Q

Which eukaroyte is found in the periodontal pcoket ?

A

t.tenax

352
Q

How is E.gingivalis transmitted ?

A

foecal oral route

353
Q

What is the relationship between E.gingivalis and periodontits ?

A

could target homeostatic bacteria

direct contributor to inflammation

354
Q

What are the 4 types of anti fungal drugs ?

A

polyenes
azoles
5-flucoytosine
echinocadnins

355
Q

What are polyenes ?

A

nystain
disrupt fungal cell membranes by interacting eith ergesterol and making the membrane leaky
topical

356
Q

What are azoles ?

A

miconazole
inhibit ergesterol biosynthesis
topical and systematic

357
Q

What is 5-flucocytosine ?

A

inhibt DNA and protein synthesis

systematic

358
Q

What are echinocardins ?

A

inhibt Beta 1-3 D-glucan aynthesis
intravenous
microfungin

359
Q

What must be considered with anti-fungal medication ?

A

fungi are slow growing- long course of treatment

consider other drugs being given

360
Q

What are dental abscesses ?

A

collection of pus which is walled off by a barrier of inflmmatory reaction

361
Q

How can abscesses develop ?

A

confined space that bacteria can gain entry to and multiply

362
Q

What is a dentoalveolar abscess ?

A

pulp death due to bacterial invasion as a result of dental caries

363
Q

What are the routes of infection for a dentoalveolar absecess ?

A 
exposed dentine tubules
pulp exposure 
bacteremia 
root fracture 
endodontic infection
364
Q

What is an endodontic infection ?

A

infected pulp

365
Q

What does root canal treatment do ?

A

clean out the canals and seal them to prevent bacterail access

366
Q

Which chemicals are used to clean out root canals ?

A

sodium hypochlorite
chlorhexdine
calcium hydroxide
iodine

367
Q

Which species are resistant to root canal treatment ?

A

enterococcus faecialis

result in flare ups

368
Q

What is a periodontal abscess ?

A

differentiated from dentoalveoalr due to a vital pulp

369
Q

How does periodontal abscess develop ?

A

foreign material in an estabished periodontal pocket

leads to swelling, eryhtrema and pus at gingival margin

370
Q

Species associated with periodontal abscesses ?

A

porphyromonas
fusobacterium
actinomyces
haemolytic strep

371
Q

How can we treat a dentoalveoalr abscess ?

A

local measures- RSI and scaling
irrigation of root canal
antispetics - chlorhexidine mouthwash
extraction

372
Q

Which bacteria are present in dental abscesses ?

A

usually anaerobes- facultative and strict

373
Q

Which facultative anaerobes can you find in dental abscesses ?

A

viridans strep
saphy
strep anginosus

374
Q

Which obligate anaerobes can be found in dental abscesses ?

A

fusobacterium
preveotella
T. denticola

375
Q

What are factors that can affect bacterial populations in abscesses ?

A

oxygen tension
availability of nutriets like proteins
bacterial interactions

376
Q

Why might you find bacterial popualtions with 3/4 species ?

A

multiple infection but only certain species survive

one species infects and paves the way for others

377
Q

What does coaggregation lead to ?

A

coinvasion of epithelial cells or dentine tubules

378
Q

What is an example of coinvasion into epithelial cells ?

A

Fusobacterium nucleatum aggreagates with S.cristatus into cells

379
Q

What is an example of coinvasion into dentine tubules ?

A

P.gingivalis and S.gordonii

380
Q

What are localsied spreads of infection ?

A

soft tissue abscesses

cellulities- inflammation spreads through connetive tissue

381
Q

What are extreme spreads of infection >

A

sinuses
osteomyelitis
adjacent fascial layers
maxillary sinus

382
Q

What is osteomyelitis ?

A

inflammation of the medullary bone - maxill and mandible

posterior extension to the cortical bone and the periosteum

383
Q

What are typical isolates found in osteomyelitis ?

A

obligate anaeroboes

actinomyces

384
Q

What are treatment optiond for osteomyelitis ?

A

local debridement
topical antispetic
antibiotics

385
Q

Give some examples of tissue sapces ?

A

pterygomandibualr space
lateral pharyngeal space
sublingual, submandibular, submental

386
Q

Where can infection from 1-6 go ?

A

sublingual space

387
Q

Where can infection from 1-3 go ?

A

submental space

388
Q

Where can infection from 6-8 go ?

A

buccal space

389
Q

Where can infection from an 8 go ?

A 
submasseteric space 
pterygomandibular space 
lateral pharyngeal space 
retropharyngeal space
mediastinum
390
Q

How can we treat dental abscesses ?

A 
local measures 
drain pus 
tooth extraction 
drain root canals 
devride infected periodontal pocket 
irrigate operculum
391
Q

When do you prescribe antibiotics ?

A

evidence of spreading infection

systemic involvement

392
Q

When is there evidence of spreading infection ?

A

lymph node involvement
swelling
lockjaw

393
Q

When is there evidence of systemic involvement ?

A

fever
dysphagia
malaise
temp over 38

394
Q

What are warning signs ?

A 
raising of tongue 
elevated floor of mouth 
neck swelling 
fever 
voice hoarosness 
breathing difficulty
395
Q

Which antibiotics can be presribed for infections ?

A

metronidazole

amoxicillin

396
Q

What is ludwigs angina ?

A

progression of dentoalveolar infection to tissue spaces
neck swelling
difficulty breathing
to mediastinum

397
Q

Which bacteria are involved in Ludwigs angina ?

A

prevotella
porporymonas
fusobacterium
anaerobic strep

398
Q

What is pericoronitis ?

A

superficial infection of operculum
usually lower 8s
local sprea of infection
infection in space between tooth and overlying tissue

399
Q

Which anaerobic bacteria are involved in pericoronitis ?

A

p.intermdium
anaerboc streptococci
fusobacterium
A.actinomycecomitans

400
Q

How can we manage pericoronitis ?

A

locla measures
irrigation
extraction
metronidazole if systemic

401
Q

What is cerviofacial actinmycosis ?

A

opportunsitic infectin caused by Actinomyces- A.isrealii
submandibular swelling/ angle of mandible swelling
thick yellow pus granules - sulphur granules

402
Q

What are the visible granules in C.actinomycosis ?

A

calcified aggregates of actinomyces filaments

403
Q

What is ANUG ?

A

poor OH, stress, immunocompromised, smokers
grey pseudomembrane - superficial infection of gingival margin
treponema and prevotella

404
Q

How can we treat ANUG ?>

A

OHi improvement
remove supra/subgingival plaque dpeosits
scaling
ultrasonic debridment

405
Q

What are seocndary forms of oral candidosis ?

A

angualr cheilitis
median rhomboid glossitis
chronic mucocutaenous candidosis

406
Q

What causes angualr cheilitis ?

A

candida
staph
strep

407
Q

What is angualr cheilitis ?

A

lesions that affect the angles of the mouth
bilatera
soreness
eryhthema

408
Q

What causes denture related angualr cheilitis ?

A

candida from mouth

409
Q

Where do staphylocci originate in angualr cheilitis ?

A

anterior part of nose

410
Q

If angualr cheilitis is fungal how do we treat ?

A

miconazole cream

411
Q

If angualr cheilitis is bacterial how do we treat ?

A

sodium fusidate

412
Q

What is median rhomboid glossitis ?

A

shape on dorsum of tongue
atrophy of filiform papillae
smoking and inhaled steroids are cause

413
Q

What is chronic mucocutanous candidosis ?

A

imapired cellular immunity agaisnt candida

assocaited with rare congenital disorders

414
Q

What is the relationship between diabetes mellitus and periodontal disease ?

A

increased periodontal disease with diabetes

periodontal inflammation may impact glycaemic control

415
Q

What is the relationship between periodontal disease and adverse pregnancy reactions ?

A

periodontal disease linked with preterm babies

F.nucleatum and P.gingivalis found in preterm baby amniotic fluid

416
Q

What is the association between cardiovascualr disease and Periodontitis ?

A

periodontal disease leads to increased inflammation

atheroscleorsis - P. gingivalis and F.nucleatum maintain inflmmation sites like plaque

417
Q

What does inflammatory periodontal disease lead to ?

A

cytokine production

LPS exposure

418
Q

What are the sources of Hallitosis ?

A

85-90% oral
5-10% nose
3% tonsils
1% other

419
Q

What are oral causes of halitosis ?

A 
poor OH 
gingivitis and periodontal disease 
oral infections 
unclean dentures 
xerostomia 
smoking 
dental abscesses
420
Q

What are the causes of xerostomia ?

A 
mouth breathing
fasting 
prolonged talking 
stress
salivary gland hypofucntion
421
Q

What are some bacterial niches where halitosis can originate ?

A

posterior dorsum of the tongue
gingival sulcus
pockets
interdental spaces

422
Q

Where else can halitosis originates ?

A

oral candidosis and oral tumours

423
Q

Why is the tongue a bacterial niche ?

A

tongue coating has deep fissures
bacteria can adhere and avoid saliva flushing
create anaerobic environment

424
Q

What type of bacteria are prominent with hallitosis ?

A

gram negative anaerobes

425
Q

What are the most active bacteria in hallitosis ?

A

P.gingivalis
T.denticola
Tannerella Forsythia

426
Q

What is hallitosis primarily caused by ?

A

degradation of sulfur containing amino acids derived from proteins from exofoliated epithelial cells, plaque or blood.

427
Q

What are some VSCs ?

A

hydrogen sulphide

dmethylsulphide

428
Q

What are some non sulfur compounds that dont cause hallitosis ?

A

skatole

cadaramine

429
Q

How can we assess halitosis ?

A

assess smell of breath, floss and tongue scrapes
use gas chromatography- sensitive to hydrogen sulphide
use BANA - detect periodontal pathogens

430
Q

What arguments are for an association between peridontal disease and halitosis ?

A

gram negative microorganisms that cause hallitosis are associated with periodontal disease
Halitosis found in those with periodontitis
elevated VSCs in pockets 4mm+

431
Q

What are the arguents against relationship between periodontitis and halltosis ?

A

periodontally healthy patients have hallitosis
tongue dorsum is main cause
periodontally pockets are partially sealed which prevent gas transfer
tongue cleaning reduces VSCs

432
Q

How can we treat hallitosis ?

A

mask the malodour
reduced the bacteria mechanically and nutrients
chemical reduction of microbe load- mouthwashes
oxidising agents like chlorine dioxide which degrade VSCs and make them non volatile

433
Q

What is FAA agar ?

A

cultivation of fastiduous anaerobic microorganism

selective if you add antiobiotics vancomycin and neomycin

434
Q

Why is there a low level of glucose in FAA agar ?

A

prevents alcohol and acid production

also essential growth factor for anaerobes

435
Q

What does reduced transport fluid do ?

A

provides anaerobic conditions acting as a reducing agent

436
Q

Is FAA selective or indicative ?

A

indicative

selective if you add antibiotics

437
Q

What is MSB ?

A

with tellurite omitted it is selective for S.Mutans and sobrinus
indicative as well

438
Q

What is TYCS ?

A

tryptone
yeast
cysteine
sucrose

439
Q

What does TYCS do ?

A

used to differentiate strep mutans from sanguis

uses high sucrose content to promote glucan formation by S Mutans which will form distinctive colonies

440
Q

Is TYCS selective or indicative ?

A

both

seletive for mutans but indicative of mutans and salivarius

441
Q

What is blood agar ?

A

nutrient rich non selective medium

442
Q

Which bacteria are common around mouth and nose ?

A

staphylococci- non haemolytic

443
Q

What is alpha haemolysis ?

A

green colour change as hydrogen peroxide vlrach the heaemoglobin in the blood agar

444
Q

What is beta haemolysis ?

A

complete lysis of RBCs

light colour

445
Q

What is gamma haemolysis ?

A

no haemolysis

446
Q

What is chlorhexidine mouthwash used for ?

A

reduces potentially pathogenic flora to a minimum to allow re establishment of a healthy balance
used in periodontal patients and pre surgery

447
Q

What does the snyder test detect ?

A

acidogenic and aciduric bacteria

potential indicative caries test

448
Q

What does the snyder medium contain ?

A

2% glucose and bromescol green

449
Q

Which bacteria are detected in the snyder test ?

A

lactobacilli - found in carious lesions as there is a low pH in carious lesions- selective

450
Q

Which carbohydrate do bacteria ferment in the snyder test ?

A

glucose into lactic, acetic and formic acid

451
Q

Why does P.gingivalis form dark colonies on blood agar ?

A

contains porphoryn pigments that contain haem

prevotella also does this

452
Q

The antibiotics vancomycin and neomycin added to FAA are selective for which bacteria ?

A

fusobacterium

453
Q

What is the selective agent in MSB agar ?

A

bacitracin- selective for S.mutans

454
Q

How do you work out CFU/ml ?

A

number of colonies x dilution factor/ volume of culture plate

455
Q

Why is CFU not the same as number of cells in a culture ?

A

CFU contains dead cells

multiple cells can make a CFU

456
Q

What is staph agar ?

A

selects for staphylococci by having a high NaCl concentration

457
Q

What is McConkey agar ?

A

selects for enterobacteria like e.coli

high concentration of bile salts

458
Q

What is candida agar ?

A

low pH , chloramphericol

selects for canddia as they tolerate a low pH in the mouth and vagina

459
Q

What is bacictracin ?

A

an antibiotic

s.sonrinus and mutans are resistant to it so they can be selected for using it

BDS stage 2 (28 decks)

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