Fusobacterium necrophorum is a species of bacteria responsible for Lemierre’s syndrome and other medical problems. It is an obligate anaerobe and is a common inhabitant of the alimentary tract within humans and animals.

F. necrophorum is a rod-shaped species of Gram-negative bacteria. It is an obligate anaerobe and is a common inhabitant of the alimentary tract within humans and animals.^[1]

F. necrophorum is responsible for 10% of acute sore throats,^[2] 21% of recurrent sore throats^[3][4] and 23% of peritonsillar abscesses^[5] with the remainder being caused by Group A streptococci or viruses. Other complications from F. necrophorum include meningitis, complicated by thrombosis of the internal jugular vein, thrombosis of the cerebral veins,^[6] and infection of the urogenital and the gastrointestinal tracts.^[7]

Although this infection is rare, researchers agree that this diagnosis should be considered in a septicaemic patient with thrombosis in an unusual site, and underlying malignancy should be excluded in cases of confirmed F. necrophorum occurring at sites caudal to the head.^[8]

F. necrophorum infection (also called F-throat^[9]) usually responds to treatment with penicillin or metronidazole, but penicillin treatment for persistent pharyngitis appears anecdotally to have a higher relapse rate, although the reasons are unclear.

This bacterium has been found to be associated with the foot disease thrush in horses. Thrush is a common fungal infection that occurs on the hoof of a horse, specifically in the region of the frog. F. necrophorum occurs naturally in the animal’s environment, especially in wet, muddy, or unsanitary conditions, such as an unclean stall.^{[10] [11]} Horses with deep clefts, or narrow or contracted heels are more at-risk to develop thrush.

F. necrophorum is also a cause for lameness in sheep. Its infection is commonly called scald. It can last for several years on land used by either sheep or cattle, and is found on most land of this type throughout the world. Due to its survival length in these areas, it is unrealistic to try to remove it. Sheep most often get scald due to breakage or weakness of the skin surrounding the hoof. This can occur due to strong footbaths, sandy soils, mild frostbite, or prolongened waterlogging of a field, and results in denaturing of the skin between the cleats.^[12]

• Fusobacterium necrophorum treatment^[13]

• 1. In adults

• Preferred regimen: Combination therapy of Metronidazole 500 mg IV q8h AND Ceftriaxone 2 gm IV q24h

• 2. In children

• Preferred regimen: Combination therapy of Metronidazole 10–15 IV mg/kg q8h AND Ceftriaxone 80–100 mg/kg q12h
• Alternative regimen (1): Imipenem
• Alternative regimen (2): Ampicillin-Sulbactam
• Alternative regimen (3): antipseudomonal penicillins
• Alternative regimen (4): Clindamycin
• Note: More frequent dosing of ceftriaxone is needed in cases of CNS infection.

^[1]