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.