<prompt> A 23 year old male patient presented with abrupt onset of fever, headache and myalgia followed by petechial rash and ahritis 2 to 10 days after exposure to a rat bite. He is diagnosed with Rat-bite fever. What is the causative organism of this disease?Klebsiella granulomatisEikenella corrodensStreptobacillus moniliformisErysipelothrix rhusiopathiae  <response>: Streptobacillus moniliformis is a gram negative, non motile, non capsulated and highly pleomorphic sho bacillus. They causes rat - bite fever. In man, organism enter through the wound caused by bite of rat. When infection is acquired by ingestion of food, milk water contaminated with excreta of rat it is known as Haverhill fever or Erythema ahriticumepidemicum. This is characterised by fever, polyahritis and petechial rash. Good to know: Klebsiella granulomatis causes donovanosis. Eikenella corrodens causes oppounistic infections. Erysipelothrix rhusiopathiae causes erysipelas. Ref :Ananthanarayanan Panikers ed- 8th pg 39. 