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Introduction to Oral Pathogens

Introduction to Oral Pathogens. There are some bacteria that cause a disease, but there are some diseases that bring about a condition that is ideal for the growth of some bacteria. -Pasteur. Reasons for Uncertainty/Confusion in Defining Microbial Periopathogens.

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Introduction to Oral Pathogens

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  1. Introduction to Oral Pathogens

  2. There are some bacteria that cause a disease, but there are some diseases that bring about a condition that is ideal for the growth of some bacteria. -Pasteur

  3. Reasons for Uncertainty/Confusion in Defining Microbial Periopathogens • “Periodontal disease” may be periodontal diseases • Mixed infections • Large number of species present • Many species are difficult to grow • Time of sampling may be wrong • Different sites in same patient may have different bacteria • Opportunistic species grow as result of disease rather than as cause. • Association studies • Carrier states • Phenotypically “normal”, but infected with pathogen • Strains of putative pathogens may vary in virulence. Some may harbor phage or plasmids.

  4. Bacteroides Group • B. fragilis • Porphyromonas • Prevotella

  5. Porphyromonas & Prevotella • Both gram-negative rods, black colonies on blood agar • After Bf, most common cause of human infection by anaerobic gram-negative bacilli • Habitat: oral cavity, upper alimentary, respiratory tracts, colon • unusual endotoxin • Infections: dental, sinus, pulmonary, human bite • Susceptible to penicillins

  6. General Characteristics of Bacteroides forsythus • Renamed in 1986 for “fusiform Bacteroides” • Gram-negative, anaerobic, pleomorphic often fusiform • Cells are nonmotile and have no flagella • This species demonstrates a distinctive surface layer • Requires exogenous N-acetyl-muramic acid for growth • One of a few oral species demonstrating strong trypsinlike activity • Periodontopathogen; associated with progressive attachment loss in subjects before therapy (RPP) and in refractory periodontitis

  7. Peptostreptococcus and Microaerophilic Streptococci • Confusing taxonomy • Some peptostrep reassigned to genus Streptococcus • Gram-positive cocci; chains; slow growers in O2 or CO2 • Habitat: normal oral flora; colon; female genital tract • Penicillin sensitive; aminoglycoside resistant

  8. Peptostreptococcus • Opportunists, often associated with other organisms • Present in cerebral abscess, pelvic peritonitis, anaerobic cellulitis, septic thrombophlebitis • Gas production; can be smelly

  9. Treponema denticola • Treponema; Greek, turning thread • General Characteristics: • Gram-negative, anaerobic, chemoorganotroph, very motile in highly viscous environment, rifampin resistant • Growth conditions: peptone-yeast extract-serum medium + fatty acids, cocarboxylase

  10. Background • Mounting evidence implicating T. denticola in the etiology of human periodontitis. • T. denticola overgrowth is synonymous with the presence of clinical inflammation. • Armamentarium of proteolytic, cytolytic, and adherence properties • Meager and confusing information about which T. denticola antigen(s) are recognized by the humoral immune system or the characteristics of the antibodies produced.

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