A 33-year- old female dairy farmer develops a severe headache and neck stiffness. A lumbar puncture is performed, and a Gram stain of the CSF obtained shows many short, gram-positive rods. Physical examination - Her temperature is 38.2°C, with no papilledema.

Figure: CSF sample, gram stain micro (high resolution) Based on the clinical findings, what could be the most likely causative agent in this case? *This case is from Docplexus Editorial Team for educative purpose only.