All of the following organisms are associated with periodontitis EXCEPT:

The primary periodontal pathogens are gram-negative anaerobes. The most significant include: Porphyromonas gingivalis (red complex), Tannerella forsythia (red complex), Treponema denticola (red complex), Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, and Prevotella intermedia. Streptococcus intermedius is a gram-positive facultative anaerobe (Streptococcus anginosus group) that is associated with deep-seated infections such as liver and brain abscesses, not typically with periodontitis. It is a normal commensal of the oral cavity that becomes pathogenic in other body sites.