Fusobacterial infections: an underestimated threat.

The involvement of fusobacteria in a wide range of human and animal infection has long been recognised. Slow-growing anaerobes, often in polymicrobial culture, they are not always identified but are present mainly in the oropharynx, from where they are bloodborne to other sites or aspirated into the lung. Fusobacterium nucleatum is commonly found in periodontal disease and produces tissue irritants such as butyric acid, proteases and cytokines. It has strong adhesive properties due to the presence of lectins, and these outer-membrane proteins mediate adhesion to epithelia and tooth surfaces, and coagglutination with other suspected pathogens. F. necrophorum may cause necrotising tonsillitis and septicaemia, leading to the spread of infection and the development of abscesses in the lung and brain--a form of Lemierre's syndrome. Calf diphtheria, foot rot and other infections in animals are well defined, with the pathogenic mechanisms involving leucotoxins, endotoxins and adhesins. A foul smell produced by butyric acid and other metabolic products is common to all fusobacterial infections. Identification using simple tests is within the scope of most laboratories.