A 35-year-old woman presented with swelling and pain of her left wrist of ten days' duration. Twelve days ago she was bitten on the left hand by her pet cat. Two days later she developed pain, redness, and swelling of her hand. O/E, Mild fever Erythematous left wrist and thenar eminence Reduced range of motion of fingers The white blood cell count was 13,000/ml, with a marked increase in the percentage of immature granulocytes. Gram stain of the wrist fluid was done. What is the most likely cause?