Oral Flora I
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Transcript of Oral Flora I
Oral Flora I
Karen Ross
2007
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Anaerobic Bacteria of Clinical Importance
Genera Anatomic SiteBacilli (rod)Gram-negative Bacteroides
Colon
Fusobacterium* Mouth, Colon
Tannerella* Mouth
Prevotella* Mouth
Porphyromonas* Mouth
Gram-positive Actinomyces* Mouth
Lactobacillus Mouth, Vagina
Propionibacterium Skin
Eubacterium, Bifidobacterium and Arachnia Mouth, Colon
Clostridium Colon, also found in the soil
Cocci (spheres)
Gram-positive PeptostreptococcusColon
Gram-negative Veillonella* Mouth, Colon
Porphrymonas gingivalis
• Gram -ve coccobacilli• Anaerobic, dark pigmentation on media containing lysed blood.• Black pigmentation due to accumulated hemin used as an iron source
for growth• The diseases collectively termed periodontitis are bacterial infections
which begin with inflammation of the periodontium, and can progress to loss of teeth. Untreated infections lead to destruction of the periodontal ligament and alveolar bone. It is estimated that over 49,000,000 people in the United States have some form of periodontitis (Cutler et al., 1995). These diseases are infectious conditions which may progress over several years with episodes of exacerbation and remission. Periodontitis occurs with higher frequency in patients with systemic diseases such as diabetes mellitus, AIDS, leukemia, neutropenia, Crohn's disease, and Down's syndrome (Neville et al., 1995)
Virulence Factors of P.gMolecules and Organelles
Proteases -arginine and lysine specific cysteine proteases
Hemagglutinins -mediate the binding of Pg to epithelial cells and erythrocytes
LPS-very different composition from enteric bacteria lacks endotoxicity
Fimbriae -peritrichous (all directions), neccesary for infection
Outer membrane vesicles -outgrowth of outer membrane, platelet aggregation, precise delivery of virulence factors, can enter where Pg cannot
Polysaccharide capsule -six serotypes, reduced phagoscytosis
Cytotoxic metabolic end products -include butyrate, propionate, have low molecular weights which allows them to easily penetrate periodontal tissue and disrupt the host cell activity
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Tsute Chen, Department of Molecular Genetics,The Forsyth Institute.
MechanismsAdhesion, colonization and dental plaque
(biofilm) formationEpithelial and Endothelial cell invasionProteolysis - proteases degrade host proteins
including fibrinogen, plasma proteins, cytokines, can also activate neutrophils
Inflammatory response -can activate and suppress components of the innate immune response.
Bone resorption, bone destruction, and bone formation inhibition -LPS, fimbrial and outer membrane consituents play a major role. Eg. LPS causes release of bone resorption mediators (cytokines) from fibroblasts, macrophages and monocytes. These mediators also induce host cell proteases that destroy both bone and connective tissue and inhibit synthesis of collagen by osteoblasts.
(Lamont et al., 1995)
gingipainsgingipainsLPSLPS
CCR5CCR5
PAR 1-2PAR 1-2TLR 2-4TLR 2-4
EndosomeEndosome
Other HIV receptorsOther HIV receptors
CCR5CCR5
CCR5 tropic HIV-1CCR5 tropic HIV-1
CXCR4 tropic HIV-1CXCR4 tropic HIV-1
CCR5CCR5
Porphyromonas Porphyromonas gingivalisgingivalis
Oral Oral
keratinocyteskeratinocytes
CD4CD4
CCR5CCR5
HIV target HIV target CD4(+) T cellsCD4(+) T cells
Courtesy of Rodrigo Giacaman-Sarah; Herzberg Lab
Morphological changes were delayed in KB-MRP8/14.
Morphological changes of epithelial cells
after exposure to P. gingivalis
Morphological changes of epithelial cells
after exposure to P. gingivalis for 24 h
wild type
fimbriae-deficient mutant
P. gingivalis proteases
Cysteine proteases
• Arg-gingipain, RgpA, RgpB
• Lys-gingipain, Kgp
Cells expressing calprotectin are more resistant to cell detachment mediated by P. gingivalis proteases, Kgp and Rgp.
Strain Phenotype
ATCC33277 Wild type
KDP129 Kgp-deficient mutant
KDP133 RgpA, RgpB-deficient mutant
KDP136 Kgp, RgpA, and RgpB-deficient mutant
Morphological changes of epithelial cells after exposure to P. gingivalis wild type and protease-deficient mutants for 24 h
Gram -ve, filament shaped, non motile, non pigmentedAnaerobe
Virulence factorsHydrolases -produces a trypsin-like protease, and an arginine-specific
cysteine protease, and a sailase.Hemolytic activity -cyteine protease, iron acquisition from erythrocytesCo-aggregation -P. gingivalis, S. cristatis Adhesion -leucine rich surface protein (BspA), binding to RBCs,
fibroblasts, leukocytes, and epithelial cells (see above)
Seok-Woo Lee, School of Dental and Oral SurgeryColumbia University
Tannerella forsythia
Treponema denticola
Motile helical rodsIrregular (3-8) spiralsGram-ve cell wallAnaerobe, able to be grown in vitro
MoleculesMajor outer membrane protein(Msp) - 53-
kDa adhesin with pore forming activity, cytotoxic for epithelial cells and erythrocytes
Proteinases -Dentilisin/PrtP/CTLP involved in cell attachment, tissue destruction, tissue invasion
Hemin- and lactoferrin-binding proteins -iron acquisition and utilises lactoferrin from the saliva
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'TREPONEMA DENTICOLA’by Joe Dixon, 2007
Treponema denticola
MechanismsMotility and chemotaxis - motility
mutants fail to infect their hosts. Maneuvering in viscous fluids, gingival crevice is highly viscous.
Hemagglutination and hemolytic activityAdhesion - Fibroblasts, extracellular
matrix, epithelial cells, endothelial cells coaggregation
Invasion-Tissue and cellular invasion, produce lesions in tissue models, penetrate epithelial and endothelial cell monolayers
Proteolytic activity Dentilisin/PrtP/CTLP disrupts cell junction and impairs epithelial monolayers
Immunosupppressive activity - lymphocyte proliferative responses to antigens and mitogens suppressed
T. d induces actin rearrangement and detachment of human gingival fibroblasts. Baehni et al., 1992
Fusobacterium nucleatum
Gram -ve, anaerobic, cigar-shaped bacilli with pointed endsRecovered mainly from periodontal pocketsIn combination with oral spirochaetes) causes fusospirochaetal
infections -acute necrotizing ulcerative gingivitis, vincents angina, cancrum oris or noma
Toxic metabolites -butyrate, proprionate, ammonium ionsCoaggregation -anchor, bridge formationAdhesion -binds to fibronectin
-binds PMNs, macrophages, lymphocytes, HeLa cells, fibroblasts, both periodontal ligament and gingival fibroblasts and buccal epithelial cells
Invasion -epithelial cells
Collaborative invasion
Edwards, Grossman, and Rudney 2006, Infect Immun 74: 654
Tissue culture experiment
F. nucleatum invades epithelial cells
S. cristatus does not invade cells
After coaggregation, S. cristatus is carried inside by F. nucleatum
Prevotella intermedia
Anaerobic, Non-motile, Short, round-ended, Gram-ve rods
VirulenceFimbriae -4 different typesHydrolasesHemolysin and hemagglutininCoaggregationAdhesionInvasion Induction of inflammatory lymphokines
Veillonella spp.
• V. parvula, V. dispar, V. atypica• Non-motile, nonsporulating, small, anaerobic Gram-ve
cocci• Commensals of the oropharynx, gastrointestinal tract
and female genital tract • Unable to use carbohydrates or amino acids, ferment
organic acids to propionic and acetic acids, CO2 and H2• Component of early plaque, may use lactic acid
produced by streptococci the early colonisers -metabolic cooperation
Capnocytophaga spp.
C. gingivalis C. ochraceaC. sputingenaC. granulosaC. haemolyticaHydrolasesTrypsin-like protease
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Actinomyces • Gram+ve anaerobic and microaerophilic• Filamentous, branching,gram-positive rods.
Older microbiologists sometimes referred to actinomyces as fungi because of the were long like fungal hyphae. However, they are only about a tenth as wide.
• They normally reside in the human mouth, throat, large intestine, vagina, and the crevices between teeth and gums, especially underneath dental plaque.
• Normal flora and is not transmitted from person to person. • Not usually virulent, reside as saprophytes in the body without
producing disease. • Problem only if they have the opportunity to grow on a surface
away from oxygen. They stick to one another, and eventually can break loose as a mass that is too big to be engulfed by the body's defense cells.
Actinomycosis• Actinomyces israelii• Tooth abscess or a tooth extraction and the endogenous organism becomes
established in the traumatized tissue and causes a suppurative infection(pus). • These abscesses are not confined to the jaw and may also be found in the
thoracic area and abdomen. • The patient usually presents with a pus-draining lesion, so the pus will be the
clinical material you send to the laboratory. • Yellow sulfur granules, characteristic of this organism, can be seen with the
naked eye. You can also see these granules by running sterile water over the gauze used to cover the lesion. The water washes away the purulent material leaving the golden granules on the gauze.
• Aggregation• Co-aggregation
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Fusobacterium nucleatum cells coaggregating with Porphyromonas gingivalis cells.
Fusobacterium nucleatum intergeneric coaggregations in the form of corn-cob
formations
Kolenbrander et al., 2000
Kolenbrander et al., 2006
Advantages of co-aggregationPhysical contact -attachmentMetabolic exchangeSmall-signal-molecule-mediated communicationExchange of genetic material
Streptococcus oralis in three-fold excess over partner Prevotella loescheii (arrows)
Fusobacterium nucleatum
P. loeschii does not coaggregate with F. nucleatum but S. oralis coaggregates with both and acts as a coaggregation bridge
Kolenbrander et al., 2006
Kolenbrander 2006
Reviews: light reading :)
Socransky and HaffageePeriodontal microbial ecologyPeriodontology 2000Vol 38:135-187, 2005
Kolenbrander et al.,Bacterial interactions and sucessions during plaque developmentPeriodontology 2000Vol 42: 47-79, 2006