34 - Microbial interactions Flashcards

1
Q

Oral Eubiosis

A

Microbial balance within the oral cavity

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2
Q

Oral Microflora

A
  • Can be resident/transient
  • Acquired from saliva, food + H20

It can also cause various diseases:

  • abscesses
  • dental caries
  • gingivitis
  • periodontal diseases
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3
Q

Interactions

A
  • Interspecies collaboration
  • Interspecies competition
  • Interspecies communication
  • Collaborative invasion
  • Bacterial co-aggregation
  • Microbial relationship
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4
Q

Interspecies collaboration

A

Some anaerobic species such as P.gingivalis need a co-aggregation to survive in the presence of oxygen

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5
Q

Interspecies competition

A

Many oral species produce substances that kill closely related competitors

eg. Wild type S.mutans

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6
Q

Interspecies communication

A

Bacteria sense other species based on their characteristics

Eg. Streptococci ferment CHO + excrete lactic acid ⇢ Veillonella uses lactic acid for nutrition

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7
Q

Collaborative invasion

A

F.nucleatum invades epithelial cells but S.Cristatus cannot

After co-aggregation ⇢ S.Cristatus is carried inside by F.nucleatum

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8
Q

Bacterial co-aggregation

A

Process that helps in development + maintenance of mixed-species biofilm communities

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9
Q

Microbial relationship

A

Complex of relations between microbial species:

  • Neutral ⇢ between 2 species that live together without affecting the other
  • Synergy ⇢ Between 2 species living together + both mutually favoured
  • Antagonism ⇢ Between 2 microbes living together + yielding inhibition of their function
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10
Q

Bacterial plaque

A

Subgingival plaque

  • G- only
  • In tooth’s sulcus

Subgingival plaque

  • On approximal, occlusal + cervical surfaces
  • Main species ⇢ Facultative anaerobes (S. Actinomyces) + G- (Veillonella, Haemophilus)
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11
Q

!!!Note!!!

A

Oral microflora varies between people

Biofilm

  • Initiated by bacterial adhesion to surface
  • Occurs when bacteria attaches to surface + excretes exopolymer
  • Exopolymer ⇢ imbeds bacteria + attracts other microbes to newly formed microfilm

Oral plaque = main biofilm in mouth

  • Attracts high concentration of bacteria
  • Leading to oral diseases
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