<prompt> Which organismal infection is highly virulent cause corneal ulcer perforation within 48 hr?Herpes simplexPseudomonasStaphylococciAspergillus  <response>: Pseudomonas bacterial keratitis is most virulent and can cause corneal ulcer perforation within 48 hours. Pseudomonas ulcer : Most common cause of infection in contact lens users Very virulent Can stimulate fungal corneal ulcer Impoant Points to Remember in Bacterial Keratitis: Symptoms more pronounced than sign. Staphyococcus most common cause for bacterial keratitis. Most common cause of contact lens related keratitis- Pseudomonas. Ulcer Serpens- Pneumococcus. Organisms that can breach intact corneal epithelium - Gonococci, Meningiococci, Shigella, Corynebacterium diphtheria, H. influenza biotype III, Listeria monocytogenes 