This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cornea, Subject name: Ophthalmology
Which organism infection is virulent and may cause corneal ulcer perforation within 48hrs? 
Select and explain. 
A. Pseudomonas, B. Aspergillus, C. Herpes simplex, D. Staphylococci
A: Pseudomonas
Answer: A: Pseudomonas 
Explanation: Ans. (a) PseudomonasRef: Khurana 6/e, p. 102* "Pseudomonas ulcers are usually associated with hypopyon, spread very rapidly & may even perforate within 48 - 72 hrs.* Pseudomonas is the most common gram negative organism causing corneal ulcer.