Abstract
Staphylococcus aureus is an important human bacterial pathogen responsible for a wide variety of ocular diseases, including sight-threatening infections such as keratitis, corneal flap melt after laser-assisted in situ keratomileusis (LASIK), cellulitis, endophthalmitis, and panophthalmitis. Staphylococcus aureus isolates that are resistant to methicillin are known as methicillin-resistant Staphylococcus aureus (MRSA) and are usually also resistant to other β-lactam antimicrobial drugs. In current practice, methicillin sensitivity is usually performed with oxacillin or cefoxitin, as methicillin is no longer commercially available in the United States. Oxacillin is more likely to maintain its activity during storage better than methicillin, while cefoxitin can give more reproducible and accurate results than tests with oxacillin or methicillin. The organisms are still called “MRSA” and not “oxacillin-resistant Staphylococcus aureus” or “cefoxitin-resistant Staphylococcus aureus” because of this historic role.