Increasing prevalence of methicillin resistance in serious ocular infections caused by Staphylococcus aureus in the United States: 2000 to 2005

PURPOSE: To report the nationwide prevalence of methicillin resistance in serious ocular infections involving Staphylococcus aureus and profile in vitro antimicrobial susceptibility of S aureus from ocular isolates over time. SETTING: Mount Sinai School of Medicine, New York, New York, USA. METHODS: Data on S aureus submitted to The Surveillance Network (TSN) by more than 200 laboratories in the United States from January 2000 to December 2005 were reviewed. The prevalence of methicillin resistance in S aureus ocular infections and in vitro susceptibility to antibiotic agents commonly used to treat or prevent ocular infections were determined. RESULTS: The proportion of S aureus infections culture-positive for methicillin-resistant S aureus (MRSA) increased from 29.5% in 2000 to 41.6% in 2005. The MRSA ocular isolates were multidrug resistant; that is, in vitro resistance to 3 antibiotic agents or more, including all fluoroquinolones tested. CONCLUSIONS: Multidrug-resistant MRSA is increasing in serious ocular infections. Based on the rate of increase in the TSN database, MRSA cultures from serious ocular infections could be more common than methicillin-susceptible S aureus within 2 to 3 years. Large-scale national surveillance programs are needed to monitor in vitro antimicrobial resistance trends in ocular isolates.