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Oral Surgery · single question

Odontogenic infections predominantly contain which type of bacteria?

  1. Obligate aerobes only
  2. Obligate anaerobes
  3. Gram-positive cocci only
  4. Facultative anaerobes only
Show answer and explanation

Correct answer: B. Obligate anaerobes

  • A. Incorrect. Obligate aerobes are not the predominant organisms in odontogenic infections — they cannot survive the hypoxic, necrotic environment.
  • B. Correct. ODONTOGENIC INFECTIONS are predominantly caused by OBLIGATE ANAEROBES (and some facultative anaerobes). As infection progresses and oxygen tension drops, obligate anaerobes (Peptostreptococcus, Fusobacterium, Prevotella, Bacteroides) predominate. These are the bacteria most commonly isolated from dental abscesses and space infections.
  • C. Incorrect. While streptococci (gram-positive cocci) are among the early colonizers, the predominant bacteria in established odontogenic infections are anaerobes.
  • D. Incorrect. Facultative anaerobes (like streptococci) are the early colonizers, but established odontogenic infections shift predominantly to obligate anaerobes.

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