Non-Spore-Forming Anaerobic Bacteria causing Endodontic Infections: Fusobacterium nucleatum

Non-spore-forming anaerobic cocci and rods are a heterogeneous group of bacteria that form the predominant bacterial population on the skin and mucous membranes in humans. The most important anaerobic gram-negative non-spore-forming bacteria are in the genera Bacteroides, Fusobacterium, Porphyromonas, Prevotella and Parabacteroides. These microorganisms are primarily opportunistic pathogens, usually responsible for endogenous infections in humans, and are more often isolated in polymicrobial associations with other anaerobic and aerobic bacteria. Almost half of the chronic sinus and ear infections and almost all periodontal infections are polymicrobial associations of gram-negative anaerobes, the most frequently isolated being Prevotella, Porphyromonas, Fusobacterium nucleatum and Bacteroides non-fragilis. These microbes have stringent nutritional requirements and grow slowly in nutrient environments in laboratory conditions for 3 or more days. A major component of their cell wall is the lipopolysaccharides (LPS), which, in the genus Bacteroides, have little or no endotoxin activity, unlike the LPS molecules in aerobic gram-negative rods such as bacteria of the genus Fusobacterium. By applying a suitable therapeutic approach and treatment, life-threatening conditions are avoided.