1. Persistence and Prevalence of MRSA on Ocular Surface following Primary MSSA/MRSA Infections Darlene Miller, DHSc, MPH, CIC David Almeida, MD, PhD Eduardo C. Alfonso, MD The authors have no financial interest in the subject matter of this poster.

2. Introduction Staphylococcus aureus remains the most common ocular pathogen recovered from ocular infections at our Institute. Colonization and persistent S. aureus infections can lead to chronic inflammation and severe ocular surface disease. Ocular Sources-BPEI 1990-June 2009,

3. Purpose To document the prevalence and persistence of (MRSA) colonization following primary S. aureus infections. To identify presister populations. To document changes in in vitro susceptibility to vancomycin among patients with chronic MRSA infections.

4. Methods Review of all MRSA Culture Positive Cases - 1990-June 2009 Colonizer= Patient with repeat MRSA positive culture after a treatment course of at least 10 days. Patient Demographics Age Sex Presenting Clinical Diagnosis Review and comparison of Vancomycin MICs

5. RESULTS MRSA Trends-All Ocular-1990-June 2009

6. Prevalence of MRSA Colonization/Persistence

7. Persistent MRSA Colonization Profile 22%, 11/50 had 3 or more positive cultures

8. Demographics-Age/Sex (N=50) Female = 54% Males = 46%

9. Clinical Diagnosis-Persistent MRSA Colonizers (N=50)

10. Change in Vancomycin MIC Among Repeat MRSA Isolates 24% increase in vancomycin MIC, (100% susceptible)

11. Summary MRSA rates increased from 8% at baseline (1990-1994) to 38% in the last 4.5 years (2005-June 2009). Persistent MRSA colonization remain stable over the 19 year period (7.7%). Persistent MRSA was more frequently recovered from conjunctivitis and women >60 yrs. 24% of repeat MRSA isolates demonstrated increased Vancomycin MICs

12. Clinical Relevance Colonization or Persistent MRSA on the ocular surface can serve as: Reservoir/foci for post surgical infections. Antigenic trigger for increased/chronic inflammation. Repeat or persistent MRSA isolation may impact in vivo efficacy of vancomycin.