Introduction to Introduction to Oral PathogensOral Pathogens
There are some bacteria that cause a There are some bacteria that cause a disease, but there are some diseases disease, but there are some diseases that bring about a condition that is that bring about a condition that is ideal for the growth of some bacteria.ideal for the growth of some bacteria.
-Pasteur-Pasteur
Reasons for Reasons for Uncertainty/Confusion in Defining Uncertainty/Confusion in Defining
Microbial PeriopathogensMicrobial Periopathogens ““Periodontal disease” may be periodontal Periodontal disease” may be periodontal
diseasesdiseases Mixed infectionsMixed infections Large number of species presentLarge number of species present Many species are difficult to growMany species are difficult to grow Time of sampling may be wrongTime of sampling may be wrong Different sites in same patient may have Different sites in same patient may have
different bacteriadifferent bacteria Opportunistic species grow as result of disease Opportunistic species grow as result of disease
rather than as cause.rather than as cause. Association studiesAssociation studies
Carrier statesCarrier states Phenotypically “normal”, but infected with pathogenPhenotypically “normal”, but infected with pathogen Strains of putative pathogens may vary in virulence. Strains of putative pathogens may vary in virulence.
Some may harbor phage or plasmids.Some may harbor phage or plasmids.
BacteroidesBacteroides Group Group
B. fragilisB. fragilis PorphyromonasPorphyromonas PrevotellaPrevotella
Porphyromonas & Porphyromonas & PrevotellaPrevotella
Both gram-negative rods, black colonies on Both gram-negative rods, black colonies on blood agarblood agar
After After BfBf, most common cause of human , most common cause of human infection by anaerobic gram-negative bacilliinfection by anaerobic gram-negative bacilli
Habitat: oral cavity, upper alimentary, Habitat: oral cavity, upper alimentary, respiratory tracts, colonrespiratory tracts, colon
unusual endotoxinunusual endotoxin Infections: dental, sinus, pulmonary, human Infections: dental, sinus, pulmonary, human
bitebite Susceptible to penicillinsSusceptible to penicillins
General Characteristics General Characteristics of of Bacteroides forsythusBacteroides forsythus
Renamed in 1986 for “fusiform Bacteroides”Renamed in 1986 for “fusiform Bacteroides” Gram-negative, anaerobic, pleomorphic often Gram-negative, anaerobic, pleomorphic often
fusiformfusiform Cells are nonmotile and have no flagellaCells are nonmotile and have no flagella This species demonstrates a distinctive surface This species demonstrates a distinctive surface
layerlayer Requires exogenous N-acetyl-muramic acid for Requires exogenous N-acetyl-muramic acid for
growthgrowth One of a few oral species demonstrating strong One of a few oral species demonstrating strong
trypsinlike activitytrypsinlike activity Periodontopathogen; associated with progressive Periodontopathogen; associated with progressive
attachment loss in subjects before therapy (RPP) attachment loss in subjects before therapy (RPP) and in refractory periodontitisand in refractory periodontitis
PeptostreptococcusPeptostreptococcus and and Microaerophilic Microaerophilic
StreptococciStreptococci Confusing taxonomyConfusing taxonomy Some peptostrep reassigned to genus Some peptostrep reassigned to genus
StreptococcusStreptococcus Gram-positive cocci; chains; slow Gram-positive cocci; chains; slow
growers in Ogrowers in O22 or CO or CO22
Habitat: normal oral flora; colon; Habitat: normal oral flora; colon; female genital tractfemale genital tract
Penicillin sensitive; aminoglycoside Penicillin sensitive; aminoglycoside resistantresistant
PeptostreptococcusPeptostreptococcus
Opportunists, often associated with Opportunists, often associated with other organismsother organisms
Present in cerebral abscess, pelvic Present in cerebral abscess, pelvic peritonitis, anaerobic cellulitis, septic peritonitis, anaerobic cellulitis, septic thrombophlebitisthrombophlebitis
Gas production; can be smellyGas production; can be smelly
Treponema denticolaTreponema denticola
Treponema; Greek, turning threadTreponema; Greek, turning thread General Characteristics:General Characteristics:
Gram-negative, anaerobic, Gram-negative, anaerobic, chemoorganotroph, very motile in highly chemoorganotroph, very motile in highly viscous environment, rifampin resistantviscous environment, rifampin resistant
Growth conditions: peptone-yeast Growth conditions: peptone-yeast extract-serum medium + fatty acids, extract-serum medium + fatty acids, cocarboxylasecocarboxylase
BackgroundBackground
Mounting evidence implicating Mounting evidence implicating T. denticola T. denticola in the etiology of human periodontitis.in the etiology of human periodontitis.
T. denticola T. denticola overgrowth is synonymous with overgrowth is synonymous with the presence of clinical inflammation.the presence of clinical inflammation. Armamentarium of proteolytic, cytolytic, and Armamentarium of proteolytic, cytolytic, and
adherence propertiesadherence properties Meager and confusing information about Meager and confusing information about
which which T. denticola T. denticola antigen(s) are recognized antigen(s) are recognized by the humoral immune system or the by the humoral immune system or the characteristics of the antibodies produced.characteristics of the antibodies produced.