Acute necrotizing ulcerative gingivitis (ANUG) occurs due to poor oral hygiene which encourages plaque to form on teeth, causing inflammation of the surrounding gum tissues. The microorganisms that are known to inhabit the damaged tissues are oral spirochaete which includes Borrelia,Fusobacteria, Bacteroidese and Peptostreptococcus. Streptococcus is not an oral spirochaete therefore is excluded. I hope this helps.
