Actinomyces israelii is classically associated with which features?

• A. Staphylococcus aureus
• B. Escherichia coli
• C. Neisseria gonorrhoeae
• D. Actinomyces israelii

Answer: (D)

Actinomyces israelii is the organism classically responsible for actinomycosis, a chronic granulomatous infection. The hallmark presentation is cervicofacial disease with indurated swelling and draining sinus tracts, often containing sulfur granules in the purulent discharge. This organism is an anaerobic, Gram-positive, branching filamentous bacterium that is part of the normal oral flora and tends to cause disease after mucosal disruption, such as dental trauma or poor dentition. Pelvic actinomycosis can occur with long-term IUD use. These features are distinctive for actinomycosis and set it apart from infections caused by Staphylococcus aureus, Escherichia coli, or Neisseria gonorrhoeae, which are associated with different clinical syndromes.