Estimated burden of methicillin-resistant Staphylococcus aureus in California hospitals after changes to administrative codes, 2005-2010.

We assess the impact of revised International Classification of Diseases, Ninth Revision, codes on methicillin-resistant Staphylococcus aureus burden in California hospitals. Codes were rapidly adopted, demonstrating new capture of colonization and continued relatively stable capture of infections. Nevertheless, despite new colonization codes, coded data demonstrated poor retention between serial hospitalizations.