Flashcards in Lecture 1 - Oral Ecology and microbial diversity Deck (62):
how do we detect bacterial species?
traditional methods include MICROSCOPY, CULTIVATION while new methods include 16S sequencing
do we have more bacterial cells or human cells?
Bray-Curtis beta diversity chart
defines that each body site harbors a distinct microbial community
study of interrelationships of organisms and their environment
specific combination necessary for survival of an organism
parameters may be PHYSICAL, CHEMICAL and biological
the hard surfaces of teeth are unique because?
they are non-shedding. Microorganisms can form stable, thick biofilms ("dental plaque")
can microorganisms invade soft tissues?
yes. in periapical and odontogenic infections
what are some soft oral surfaces bacteria can adhere to?
hard oral surfaces are either ___________ or _________
subgingival or supragingival
floating in water
attached to a surface in biofilms
example of biofilms
plaque on teeth
gunk in drains
rings in toilets
slippery coating on rocks in streams
biofilms are made up of ______________ and ____________ in an ________ environment
the sticky material that holds biofilm together is
what are the 3 stages of biofilm life cycle?
T/F biofilm can be formed by single bacterial species
T/F biofilms often include many species of bacteria
T/F biofilms also include other micro-organisms like fungi, algae, protozoa
What turns on biofilm-adaptive genes?
when bacteria detects surfaces
when bacteria detects each other (quorum sensing)
when signals pass between bacteria
____________: stable, slow-growing communities that are highly resistant to antibiotics, host defenses and mechanical disruptions (antiseptics and disinfectants)
what are the 3 primary mechanism for biofilm antimicrobial resistance?
1. slowing of diffusion
2. "persister cells": alive but metabolically inactive survive and repopulate biofilm
3. exchange of resistance genes
T/F most bacteria in the mouth is free-floating
They need to attach or they'd be lost
biofilms can cause what 4 things?
osteonecrosis secondary to bisphosphonate therapy
T/F to prevent oral biofilms we might need to prevent invasive diseases like cellulitis as well
what are the 3 surface sites for adherence?
host surfaces (receptor molecules)
direct bacterial interactions
promotes by providing binding sites or inhibits by agglutinating and clearing
salivary binding is done by what 4 methods?
what common measures are used to disrupt bacterial adherence in the mouth?
toothbrush and floss
T/F the percentage of oxygen is greater in a closed mouth than in the air
F 12-14% oxygen in mouth. 21% in air
Positive oxidation-reduction potential means LOW oxygen (T/F)
+ = aerobe = high oxygen
- = anaerobe = low oxygen
what requires oxygen at atmospheric levels for growth?
can switch between aerobic and anaerobic metabolism
facultative anaerobes or facultative aerobes
requiring low levels of oxygen
anaerobic metabolism but tolerates the presence of oxygen
do not use oxygen as nutrient. Oxygen is toxic, killing or inhibiting growth
obligate anaerobes or aerophobes
sensitivity of anaerobes to oxygen is due to the genetic inability to make enzymes like:__________, ____ and _________
T/F In the absence of enzymes like catalase and peroxidase, oxygen products with superoxide and peroxide cannot cause damage to cellular components
they can cause damage
Which enzyme(s) detoxify oxygen radicals that are generated by living systems in presence of oxygen?
The distribution of Which enzymes(s) determines their ability to exist in the presence of oxygen?
T/F Older plaque gets thick and becomes sheltered from oxygen
Older plaque has higher oxidation-reduction potential and corresponding shift in microflora
F - lower Eh
T/F aerobic species are found primarily in oxygen-protected sites like the sulcus or mature coronal plaque
F - anaerobic
which species are found in supragingival plaque?
facultative and microaerophilic
what common therapy is designed to exploit oxygen sensitivity of oral bacteria?
T/F bacterial fermentation of sugars to lactate is an example of directly affecting pH
F - indirect
Direct method example - drinking soft drink
pH normally ranges from __-____
low pH inhibits most species except:
acid tolerant (aciduric) strep and lactobacilli
what are the two major physical nutrient niches in oral cavity?
supragingival - saliva and ingested food
subgingival - crevicular food and cells
2 inorganic salts
3 amino acids
T/F endogenous nutrients are not sufficient for plaque.
endogenous nutrients are not sufficient for caries.
F (they are sufficient)
T - they need exogenous carbs
which secretory immunoglobulin in saliva prevents adhesion?
which immunoglobulin in crevicular fluid is directed against periodontally important organisms both systemically and locally produced?
what is the main defense of innate immunity?
epithelial barrier and desqaumation
what are the major salivary proteins?
alpha-amylase: digests starches and binds bacteria
which salivary defense generates superoxide radicals which inactivate bacterial enzymes leading to bacterial death?
which salivary defense binds iron so that it is not bioavailable to bacteria?
salivary lactoferrin and serum transferrin
which salivary defense digest peptidoglycan in bacterial cell wall leading to osmotic disruption and cell death?
which salivary defense modulates salivary calcium and phosphate chemistry?
acidic proline rich proteins and statherin
which bacterium converts lactate to propionate?
T/F veillonella lowers pH for acid-sensitive strep
F - raises pH
Which vitamin is synthesized by veillonella parvula?
vitamin K3 is used by which two bacteria?
Vitamin K3 synthesis and use is an example of what?
Which strep bacterium produces enocin to inhibit s. pyogenes?
organisms occupy niche, preventing establishment of new strains is: