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Oral Flora II
Karen Ross
2007
Identification of Oral Microorganisms
16S DNA based detection
Use 2 oligo-nucleotide primers universal to ALL bacteria
16S rDNA, PCR amplification of the total saliva or plaque
DNA pool, clone the PCR product and sequence.
Variation allows similar species to be distinguished.
Currently over 125,000 bacterial 16S sequences have been
deposited in major public databases (Genbank, Ribosomal
Database Project.
Phylogeny -can construct a tree of evolutionary
relationships
In the oral cavity more than 700 bacterial species or
phylotypes have been detected. At least 50% have not
been cultivated yet.
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Schachtele et al.,2007 Oral Streptococci: Commenals and opportunistic
pathogens (chapter 16) in Molecular Biology of Streptococci.
Nasopharynx
• S. pneumoniae
Vestibular mucosa
• S. vestibularis
Buccal mucosa
• S. mitis
• mitis group
• anginosus group
Tooth surface
• mitis group
• mutans group
• anginosus
group
Saliva
• S. salivarius
• S. mitis
• S. oralis
• mitis group
• anginosus group
Tongue
• S. salivarius
• S. mitis
Tonsils
• S. sanguis
• S. mitis
• S. mutans
• mitis group
• anginosus group
Pharynx
• S. mitis
• S. oralis
• mitis group
• anginosus group
Windows of Colonization
S. mitis
A
S. sanguinis
B
S. mutans
C
0
6
12
18
Age (months)
24
30
36
Mutans Group
• S. mutans and S. sobrinus most common
Virulence factors
• Specific adherence to tooth surface using antigen I/II
adhesin and GTF (glycosyl transferase )
• Production of extracellular polysaccharides (dextran)
allows the cariogenic bacteria to stick onto the teeth and
form a biofilm
• acid-tolerance (aciduricity)
• Able to maintain microbial growth and continue acid
production at low pH values
• Rapid metabolism of sugars to lactic and other organic
acids
• Lower the pH to below 5.5, the critical pH. Drives the
dissolution of calcium phosphate (hydroxyapatite) of the
tooth enamel (acidogenicity)
• Accumulation of intracellular polysaccharides
(carbon/energy reserve)
Mitis salivarius agar levans and dextrans
Streptococcus mitis
• Gram+ve cocci
• Binds amylase (breaks down starch in glucose)
• Commensal - pathogen
• Shares 99% sequence identity with S. pneumoniae
• Endocarditis, toxic shock-like activity
Virulence
• Pneumococcal ply gene for pneumolysin and surface adhesin
PsaA found in many strains
• Bind platelets
• Members of the mitis group are naturally competent and able
to take up foreign DNA
Streptococcus
pneumoniae
•
•
•
Pneumococcus, Diplococcus pneumoniae
facultative anaerobic, gram+ bacteria, cocci in pairs, lancet-shaped,
fastidious
Pneumonia, meningitis, sometimes occult bacteremia
• Nasopharynx in up to 60% of the population
•
Major virulence factor is the capsule
– Antiphagocytic
– non-encapsulated organisms are avirulent
• Pneumolysin, pore forming hemolysin
–
–
–
–
Stimulates production of inflammatory mediators
Activates phopholipases in endothelial cells
Toxic to pulmonary endothelial and epithelial cells
Inhibits cilial beat
Endocarditis
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•Certain dental or medical
procedures. Dental procedures
that cause bleeding may allow
bacteria to enter your
bloodstream. Bacteria may also
be a concern with procedures
done elsewhere in the body,
such as in the respiratory tract.
•An infection or other
medical condition. Bacteria
may spread from an infected
area, such as a skin sore. Gum
disease, a sexually transmitted
disease or an intestinal disorder
— such as inflammatory bowel
disease — also may give
bacteria the opportunity to
enter your bloodstream.
•Catheters or needles.
•Common activities. Even
everyday activities such as
brushing your teeth or chewing
food can allow bacteria to enter
your bloodstream — especially
if your teeth and gums are in
poor condition.
Oral streptococci and infective endocarditis
•
•
•
•
•
•
•
•
Oral cavity -cause no known disease in the oral cavity except for
cariogenic mutans streptococci
Blood -systemic pathogens, major cause of infective endocarditis
Coagulopathies in neutropenic or immunocompromised patients
Enter the blood stream on a daily occurrence in most people, brushing
ones teeth or eating an apple
S. sanguinis, S. oralis, and S. gordonii (viridans streptococci)
are the most common oral streptococcal species recovered from the
platelet vegetations
Attach to and colonize diseased or injured heart valves.
Virulence factors include production of dextran, glucan and other
exopolysaccharide polymers which serve to encase colonized
streptococci on the heart valve and resist antimicrobial attack of
phagocytic cells antibodies, complement and antibodies.
Able to induce platelet aggregation.
Able to bind connective tissues
Microbiota of the human mouth in health and disease
Health
Teeth
Streptococci
Streptococcus
Streptococcus
Veillonellae
Streptococcus
Streptococcus
Actinomyces
mitis bv. I
gordonii
samguis
oralis
Tongue
S. mitis bv. 2
Streptococcus salivarius
Disease
Dental caries
S. sanguis
S. oralis
Mutans streptococci
Veillonellae
S. mitis bv. I
S. gordonii
Actinomyces
Lactobacilli
Gingivitis
Actinomyces naeslundii
S. sanguis
Fusobacterium nucleatum
Selenomas sputigena
Haemophilus parainfluenzae
Actinomysces israelii
S. mitis
Peptostreptococcus
Prevotella intermedia
Campylobacter sputorum
Veillonellae
Chronic periodontitis
Clone 1025
TM7
Fusobacterium animalis
Atopobium parvulum
Eubacterium sp. Strain
PUS9.170
Abiotrophia adiacens
Dialister pneumosintes
Filifactor alocis
Selenomonas sp. Strain GAA14
Streptococcus constellatus
Campylobacter rectus
Chronic periodontitis contd.
Tannerella forsythia
Porphyromonas endodontalis
Wolinella recta
Treponema sp. Strain I:G:T21
F. nucleatum
Atopobium rimae
Megasphaera sp clone BB166
Catonella morbi
Eubacterium saphenum
Gemella haemolysans
Streptococcus anginosus
Campylobacter gracilus H.
parainfuenzae
Prevotella tannerae
Porphymonas gingivalis
Petostreptococcus micros
Localized aggressive
peridontitis (LAP)
Eikenella corrodens
Capnocytophaga sputigena
Actinobaccilus
actinomycetemcomitans
P. intermedia
Lactobacillus
•
•
•
•
•
Gram +ve cocobacilli alpha or non hemolytic.
L. casei, L. rhamnosus, L. acidophilus, L. oris
Ferment carbohydrates to form acids (acidogenic)
Tolerate acid (aciduric)
Major members of the normal flora of the vagina. The lactic
acid product of their metabolism helps to maintain the low pH
of the normal female genital tract that inhibits the growth of
pathogens
• Rarely cause disease
• Lactobacilli in the oral cavity probably
contribute to acid formation that leads to
dental caries.
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Lactobacillus species and a vaginal squaemous epithelial cell. CDC
Actinobacillus
actinomycetemcomitans
• Leukotoxin -binds monocytes, neutrophils and some
lymphocytes, forms pores and leakage of contents
• Cytotoxins -cytolethal distending toxin
(CDT)/immunosupressive factor (ISF)
• LPS -bone resorption, platelet aggregation and skin necrosis
• Fc-binding proteins -proteins that are associated with or
released from the cell surface that bind the Fc region of Igs.
Can compete with neutrophils for binding to the Fc and
therefore inhibit phagocytosis.
• Membranous vesicles (blebs)
• Extracellular amorphous material
• Fimbriae
Mechanisms
Adhesion
Invasion of epithelial cells
Colony phase variation -smooth and rough forms,
rough colony variants heavily fimbriated
Interference with host defense mechanisms inhibit PMN chemotaxis, resists phagocyte killing
(capsularlike material), causes release of
inflammatory mediators by immune cells.
Bone resorption -surface associated material
(SAM) containing a heat shock protein acts
directly onosteoclasts, LPS and proteolysissensitive factor in microvesicles.
Apoptosis -leukotoxin-mediated killing through the
activation of caspases, removal of acute
inflammatory cells
Fine et al., 1999
Dentin tubule infections
Pulpitis, pulp necrosis and
infection of the root canal
system
Streptococci most commonly
identified.
Obligate anaerobes also in
high numbers
Trench mouth
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It is also known as ”Vincent’s stomatitis”,
"Vincent's angina”, or "acute necrotizing
ulcerative gingivitis” (ANUG).The
common name was probably coined
during World War I when many soldiers
suffered from the condition. There are a
number of other theories to the origin of
the name. Vincent's angina was named
after French physician Jean Hyacinthe
Vincent (1862-1950)
Fusobacterium nucleatum and the oral
spirochaetes, Treponema spp. Forming a
fusospirochaetal complex. If you add
Clostridium perfringens you can get an
oral gas gangrene equivalent.