What type of organism is Actinomyces israelii?

Actinomyces israelii is classified as a Gram-positive anaerobic rod. This organism belongs to the genus Actinomyces, which is known for its filamentous bacterial structure and its characteristic growth in anaerobic conditions.

Actinomyces israelii is part of the normal flora of the human oral cavity and gastrointestinal tract but can be pathogenic under certain conditions, leading to diseases such as actinomycosis. Being Gram-positive means that its cell wall retains the crystal violet stain used during the Gram staining procedure, appearing purple under a microscope. The anaerobic nature signifies that it can grow in environments devoid of oxygen, which is crucial for its survival and pathogenesis.

This classification is key in microbiology as it informs treatment options and understanding how the organism interacts with the human host, particularly in terms of susceptibility to antibiotics and the type of immune response that may be elicited.