necrobacillosis

Necrobacillosis is an infectious disease caused by necrobacilli, most commonly Fusobacterium necrophorum, a Gram-negative anaerobic bacillus that is part of the normal mucosal flora of humans and many animals. It is an opportunistic pathogen that causes necrotizing, suppurative infections when tissue integrity is breached or immunity is compromised.

In veterinary medicine, necrobacillosis is particularly associated with cattle and other ruminants, where Fusobacterium necrophorum commonly contributes to liver abscesses, calf diphtheria (necrotic laryngitis), and other septic lesions of the head, neck, or thorax. In humans, infections range from pharyngitis and peritonsillar abscess to more invasive diseases such as septicemia and Lemierre’s syndrome, although the term necrobacillosis is largely historical in contemporary medical usage.

Transmission and risk factors include poor oral hygiene, recent trauma to mucosal surfaces, dehydration, and conditions that favor anaerobic growth. The organism produces tissue-destructive enzymes and toxins that promote necrosis and abscess formation and can spread via the bloodstream.

Diagnosis relies on detection of fusobacteria in abscess material or tissue, typically by anaerobic culture and microscopy showing slender, fusiform Gram-negative rods; molecular methods may aid detection. Differential diagnoses include other anaerobic and facultative pathogens causing necrotizing infections.

Treatment involves antibacterial therapy effective against anaerobes (for example, beta-lactam antibiotics with beta-lactamase inhibitors or clindamycin, often with metronidazole), plus surgical drainage or debridement of necrotic tissue when indicated. Management also addresses underlying predisposing conditions and supportive care. Prognosis varies with the site and extent of infection.