microbiology need to know

Question 1

how is a biofilm formed?

Answer 1

• adhesion to surface via weak VDW forces- if not removed then anchor onto surface more permanently using cell adhesion structures such as pili
• colonisation-biofilms grown via cell divison and recruitment
• accumulation
• complex community
• dispersal- biofilms spread and colonise new surfaces

Question 2

what factors affect colonisation growth?

Answer 2

• surface roughness
• whether the surface is hydrophobic or hydrophillic

Question 3

what is a biofilm?

Answer 3

a matrix-enclosed bacterial or fungal population adherant to each other and/or surfaces or interfaces

Question 4

what is the difference between candidosis and candidiasis?

Answer 4

candidosis affects the mouth
candidiasis has systemic general effects

Question 5

give examples of candida species

Answer 5

• albicans
• glabrata
• tropicalis
• parapsilosis
• krusei

Question 6

which 2 organisms are resistant to flucanozole?

Answer 6

• candida glabrata
• candida krusei

Question 7

define “faculatively anaerobic”

Answer 7

usually respires aerobically but can respire anaerobically if no air present

Question 8

define “obligately anaerobic”

Answer 8

can only breathe anaerobically
harmed in the presence of oxygen

Question 9

define “canophilic anaerobic”

Answer 9

thrive in high cone of CO2

Question 10

define micro aerophilic

Answer 10

requires oxygen but at a lower cone than is available in the atmosphere

Question 11

give 5 methods of identifying micro-organisms

Answer 11

• gram staining
• ziehl-neelsen staining
• PCR
• blood agar, selective agar (mannitol salt)
• H&E staining

Question 12

what microorganism causes caries (most commonly)?

Answer 12

streptococcus mutans

Question 13

what gram stain is streptococcus mutans?

Answer 13

gram positive cocci

Question 14

give 4 examples of cariogenic bacteria

Answer 14

• streptococcus mutans
• lactobacillus acidophilis
• acitnomyces viscosus
• nocardia spp

Question 15

give virulence factors of cariogenic bacteria

Answer 15

• synthesis of glucans
• extrsuion of hydrogen ions through ATPase
• polysaccharides store glycogen and protect the matrix

Question 16

what bacteria are responsible for periodontal disease?

Answer 16

• prevotella intermedia
• porphyromonas gingivalis

Question 17

which microorganisms are found in the red section of Socransky’s model?

Answer 17

porphyromonas ginigivlalis
tannerella forsythia
treponema denticola

Question 18

what are the virulence factors of candida albicans?

Answer 18

phospholipase contributes to host cell penetration
haemolysin facilitates hyphal invasion
proteinase aids in adhesion to epithelial cells

Question 19

how is denture stomatitis diagnosed in the lab?

Answer 19

smear test / microscopy
swab /culture on sabouraud’s agar / germ tube formation
angular cheilitis and acute pseudomembranous candidosis also the same

Question 20

what term is used to describe a collective group of microorganisms within the oral cavity and what are they referred to when they attach to a surface

Answer 20

microbiome

attached to surface - biofilm

Question 21

what are key microbial stages of caries plaque formation

Answer 21

adhesion
collonisation
maturation
acid prodcution

Question 22

what are virulence factors used by strep. mutans for enamel dissolution

Answer 22

glucans (glucosyltransferase - attach)

ATPAse (control pH)

Question 23

what is the bacterium associated with secondary endodontic infections

Answer 23

enterococcus faecalis

Question 24

what are virulence factors of enterococcus faecalis

Answer 24

gelatinase
superoxide
cytolysins
adhesins
collagenase

Question 25

why is it difficult to determine causality from a specific bacteria in endodontic infection

Answer 25

sterile sampling procedures active/functional bacteria

Question 26

what culture independent technique could be used to assess changes in the oral microbial populations following antibiotic exposure

Answer 26

next generation sequencing

Question 27

what is the limitation of next generation sequencing

Answer 27

limited to describing what is present rather than what communities are causing the problem

Question 28

what are systemic diseases associated with periodontal biofilms

Answer 28

periodontitis Rheumatoid arthritits

Question 29

why do biofilms not allow antibiotics to penetrate them?

Answer 29

* biofilms can produce a penetration LPS which prevents antimicrobials and antibiotics from penetrating * require mechanical disruption- medication alone will not remove them

Question 30

what is the process that leads to inflammation?

Answer 30

* vasodilation- increased blood flow (redness and warmth) * increased permeability- causes swelling * concentration of red cells- decreased velocity, stasis of blood flow * leukocyte adhesion and migragion- accumulation of inflammatory cells

Question 31

give 2 bacterial dection methods

Answer 31

* PCR test * culture on suitable agar medium

Question 32

what is required into order to complete a PCR test?

Answer 32

* double strnaded DNA template * primers specific to the particular gene * dNTPs * enzyme Tag SNA polymerase- catalyses the synthesis of new DNA strands

Question 33

what gene do PCR primers target?

Answer 33

165 rRNA gene

Question 34

what is the main microorganism associated with endodontic infections?

Answer 34

E. faecalis

Question 35

What are the classifications for candida

Answer 35

Pseudomemranous - thrush Erythematous - denture/HIV Hyperplastic - Leukoplakia Angular Chelitis Chronic Mucocutaneous

Question 36

What microbes because candida infections

Answer 36

Albicans Glabrata Krusei Tropicalis Parasilosis

Question 37

What candida species are resistant to fluconozole

Answer 37

Glabrata Krusei

Question 38

why is it difficult to determine which bacteria is the cause of an endodontic infection?

Answer 38

sterile sample procedures are required difficult to determine between active/functional bacteria

Question 39

What are virulence factors of Candida Albicans

Answer 39

Phospolipase - host cell penetration Hemolysin - Facilitates Hyphal invasion Proteinase - Adhesion to epithelial cells

Question 40

What are risk Factors for candida

Answer 40

Denture wearer HIV Immunocompromised patients Prolonged Steroid/Antibiotic Diabetic

Question 41

name virulence factors of E. faecalis

Answer 41

* gelatinase * superoxide * cytoglycins * adhesins * collagenase

Question 42

What are the treatments for patients with candida

Answer 42

Immunocompromised - systemic (fluconozole) and topical (nystatin or chlorhexidine) Dry mouth - Topical only Good OH - Systemic or topical Bad OH - OHI and CHLORHEXIDINE

Question 43

what do gram + bacteria stain purple?

Answer 43

thick petigloglycin layer in cell wall

Question 44

what microbes area associated with gingivitis

Answer 44

A. A. Provotella Intermedia Fusobacterium

Question 45

what microbes area associated with perio

Answer 45

P. Gingivalis T. forsynthia T. Denticola Provatella intermedia

Question 46

What are systemic implications of periodontal microbes

Answer 46

Diabetes RA

Question 47

what does it mean if clearing appears around a metronidaole disc on an agar plate?

Answer 47

a gram negativ anaerobe is forming

Question 48

What are virulence factors of perio microbes

Answer 48

Adhesion - Fimbriae Elaboration of Proteases - Phospholypase Endotoxins Capsular Polysaccharides Metabolic By-Products

Question 49

describe next generation sequencing

Answer 49

culture independent assesses changes in a population only determines what is present

Question 50

What are methods for sampling

Answer 50

Oral Rinse Oral Swab Biopsy Plaque sample

Question 51

what microorganisms are responsible for caries?

Answer 51

* streptococcus mutans * lactobacillus * prevotella spp * actinomyctes

Question 52

What is the methodology of antibiotics

Answer 52

inhibit cell wall synthesis cause injury to the plasma membrane of bacteria Inhibit transcription so cant reproduce Inhibit protein synthesis - cant reproduce

Question 53

give virulence factors for cariogenic microbes

Answer 53

* extracellular polysaccharides - adhesion * glucans- adhesion * ATPase- control pH * acidogenicity- produces acid * acid tolerant- survives at low pH

Question 54

How do bacteria become resistant to treatment

Answer 54

adapt cell wall to block entry of antibiotics Produce inactivating enzymes that destroy active component of drug treatment Alter target molecule to stop drug binding to bacteria and evade detection Efflux pump - bacteria produce efflux pump which removes drug out of the cell and lowers drug concentration inside cell

Question 55

what is a contra indication of fluconazole

Answer 55

warfarin and statin

Question 56

hoe do you break the chain of infection

Answer 56

Infectious agent - diagnosis/treatment Reservoir - disinfection Portal of exit - hand-washing and control aerosol/splatter Means of transmission - isolation, disinfection and hand-washing Portal of entry - first aid and hand hygiene Susceptible host - immunisation and treat underlying disease

Question 57

what are the stages of caries plaque formation?

Answer 57

adhesion collonisation maturation acid production