| Gram-negative bacteria |
| Bacteroides fragilis group: B. fragilis, B. thetaiotaomicron, B. distasonis, B. ovatus, B. vulgatus |
| Pigmented Prevotella (formerly Bacteroides): P. intermedia, P. melaninogenica, P. corporis, P. denticola, P. loescheii, P. nigrescens |
| Prevotella (other): P. bivia (formerly B. bivius), P. disiens (formerly B. disiens), P. oralis (formerly B. oralis) |
| Porphyromonas asaccharolytica (formerly B. asaccharolyticus) |
| Fusobacterium: F. nucleatum, F. necrophorum, F. varium |
| Bilophila: B. wadsworthia |
| Gram-positive cocci |
| Peptostreptococcus: P. intermedius, P. micros, P. anaerobius, P. magnus, P. asaccharolyticus, P. prevotii |
| Gram-positive, spore-forming bacilli |
| Clostridium: C. perfringens, C. difficile, C. sporogenes, C. sordellii, C. septicum, C. tertium, C. ramosum, C. novyi, C. histolyticum, C. bifermentans, C. innocuum, C. tetani, C. botulinum |
| Gram-positive, non-spore-forming bacilli |
| Cutibacterium (formerly Propionibacterium): C. acnes |
| Eubacterium: E. lentum |
| Bifidobacterium: B. dentium |
| Actinomyces: A. israelii, A. naeslundii, A. odontolyticus, A. viscosus |