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Need to Know > microbiology need to know > Flashcards

microbiology need to know Flashcards

1
Q

how is a biofilm formed?

A
  • 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
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2
Q

what factors affect colonisation growth?

A
  • surface roughness
  • whether the surface is hydrophobic or hydrophillic
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3
Q

what is a biofilm?

A

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

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4
Q

what is the difference between candidosis and candidiasis?

A

candidosis affects the mouth
candidiasis has systemic general effects

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5
Q

give examples of candida species

A
  • albicans
  • glabrata
  • tropicalis
  • parapsilosis
  • krusei
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6
Q

which 2 organisms are resistant to flucanozole?

A
  • candida glabrata
  • candida krusei
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7
Q

define “faculatively anaerobic”

A

usually respires aerobically but can respire anaerobically if no air present

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8
Q

define “obligately anaerobic”

A

can only breathe anaerobically
harmed in the presence of oxygen

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9
Q

define “canophilic anaerobic”

A

thrive in high cone of CO2

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10
Q

define micro aerophilic

A

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

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11
Q

give 5 methods of identifying micro-organisms

A
  • gram staining
  • ziehl-neelsen staining
  • PCR
  • blood agar, selective agar (mannitol salt)
  • H&E staining
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12
Q

what microorganism causes caries (most commonly)?

A

streptococcus mutans

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13
Q

what gram stain is streptococcus mutans?

A

gram positive cocci

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14
Q

give 4 examples of cariogenic bacteria

A
  • streptococcus mutans
  • lactobacillus acidophilis
  • acitnomyces viscosus
  • nocardia spp
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15
Q

give virulence factors of cariogenic bacteria

A
  • synthesis of glucans
  • extrsuion of hydrogen ions through ATPase
  • polysaccharides store glycogen and protect the matrix
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16
Q

what bacteria are responsible for periodontal disease?

A
  • prevotella intermedia
  • porphyromonas gingivalis
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17
Q

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

A

porphyromonas ginigivlalis
tannerella forsythia
treponema denticola

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18
Q

what are the virulence factors of candida albicans?

A

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

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19
Q

how is denture stomatitis diagnosed in the lab?

A

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

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20
Q

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

A

microbiome

attached to surface - biofilm

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21
Q

what are key microbial stages of caries plaque formation

A

adhesion
collonisation
maturation
acid prodcution

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22
Q

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

A

glucans (glucosyltransferase - attach)

ATPAse (control pH)

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23
Q

what is the bacterium associated with secondary endodontic infections

A

enterococcus faecalis

24
Q

what are virulence factors of enterococcus faecalis

A

gelatinase
superoxide
cytolysins
adhesins
collagenase

25
Q

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

A

sterile sampling procedures

active/functional bacteria

26
Q

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

A

next generation sequencing

27
Q

what is the limitation of next generation sequencing

A

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

28
Q

what are systemic diseases associated with periodontal biofilms

A

periodontitis
Rheumatoid arthritits

29
Q

why do biofilms not allow antibiotics to penetrate them?

A
  • biofilms can produce a penetration LPS which prevents antimicrobials and antibiotics from penetrating
  • require mechanical disruption- medication alone will not remove them
30
Q

what is the process that leads to inflammation?

A
  • 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
31
Q

give 2 bacterial dection methods

A
  • PCR test
  • culture on suitable agar medium
32
Q

what is required into order to complete a PCR test?

A
  • double strnaded DNA template
  • primers specific to the particular gene
  • dNTPs
  • enzyme Tag SNA polymerase- catalyses the synthesis of new DNA strands
33
Q

what gene do PCR primers target?

A

165 rRNA gene

34
Q

what is the main microorganism associated with endodontic infections?

A

E. faecalis

35
Q

What are the classifications for candida

A

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

36
Q

What microbes because candida infections

A

Albicans
Glabrata
Krusei
Tropicalis
Parasilosis

37
Q

What candida species are resistant to fluconozole

A

Glabrata
Krusei

38
Q

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

A

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

39
Q

What are virulence factors of Candida Albicans

A

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

40
Q

What are risk Factors for candida

A

Denture wearer
HIV
Immunocompromised patients
Prolonged Steroid/Antibiotic
Diabetic

41
Q

name virulence factors of E. faecalis

A
  • gelatinase
  • superoxide
  • cytoglycins
  • adhesins
  • collagenase
42
Q

What are the treatments for patients with candida

A

Immunocompromised - systemic (fluconozole) and topical (nystatin or chlorhexidine)

Dry mouth - Topical only

Good OH - Systemic or topical

Bad OH - OHI and CHLORHEXIDINE

43
Q

what do gram + bacteria stain purple?

A

thick petigloglycin layer in cell wall

44
Q

what microbes area associated with gingivitis

A

A. A.
Provotella Intermedia
Fusobacterium

45
Q

what microbes area associated with perio

A

P. Gingivalis
T. forsynthia
T. Denticola
Provatella intermedia

46
Q

What are systemic implications of periodontal microbes

A

Diabetes
RA

47
Q

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

A

a gram negativ anaerobe is forming

48
Q

What are virulence factors of perio microbes

A

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

49
Q

describe next generation sequencing

A

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

50
Q

What are methods for sampling

A

Oral Rinse
Oral Swab
Biopsy
Plaque sample

51
Q

what microorganisms are responsible for caries?

A
  • streptococcus mutans
  • lactobacillus
  • prevotella spp
  • actinomyctes
52
Q

What is the methodology of antibiotics

A

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

53
Q

give virulence factors for cariogenic microbes

A
  • extracellular polysaccharides - adhesion
  • glucans- adhesion
  • ATPase- control pH
  • acidogenicity- produces acid
  • acid tolerant- survives at low pH
54
Q

How do bacteria become resistant to treatment

A

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

55
Q

what is a contra indication of fluconazole

A

warfarin and statin

56
Q

hoe do you break the chain of infection

A

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

57
Q

what are the stages of caries plaque formation?

A

adhesion
collonisation
maturation
acid production

Need to Know (21 decks)

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