Final answer:
The most likely etiology for the patient's condition is bacterial keratitis, commonly caused by Staphylococcus epidermidis and/or Pseudomonas aeruginosa.
Step-by-step explanation:
The most likely etiology for the patient's condition is bacterial keratitis. Bacterial keratitis is commonly caused by Staphylococcus epidermidis and/or Pseudomonas aeruginosa. Contact lens users are at a greater risk for developing this infection because these bacteria adhere well to the surface of the lenses. Proper care of contact lenses and avoiding overnight wear can greatly reduce the risk of infection.
Prompt and aggressive treatment with antibiotics is important to prevent blindness. The causative agent can be identified using bacterial cultures, Gram stain, and diagnostic tests of the isolated pathogen.