An alcoholic person presents with pain in the right eye. On examination an ulcer is noted in the inferior cornea and the surrounding cornea is clear. Scraping took from the ulcer showed large, square-ended gram-negative diplobacilli. Which of the following is the most likely causative agent?

This patient has developed corneal ulcer secondary to infection with moraxella liquefaciens. It usually causes indolent oval ulcer that usually affects the inferior cornea and progresses into the deep stroma over a period of days. Scrapings taken from the lesion may contain large, square-ended Gram-negative diplobacilli. It often occurs in a patient with alcoholism, diabetes mellitus, or other causes of immunosuppression. Pseudomonas corneal infection often is associated with soft contact lenses especially extended-wear lenses. Scrapings from the ulcer may contain long, thin Gram-negative rods that are often few in number. Ref: Biswell R. (2011). Chapter 6. Cornea. In P. Riordan-Eva, E.T. Cunningham, Jr. (Eds), Vaughan & Asbury's General Ophthalmology, 18e.