Screen of Selleck library.

Members of the Selleck library of Food and Drug Administration-approved drugs (catalog no. L1300; Selleck Chemicals, Houston, TX) were screened for agents that potentiate the antimicrobial activity of mupirocin toward S. aureus strain UAMS-1. To do so, 1 × 10⁵ CFU of S. aureus UAMS-1 was added to individual wells of a 96-well microtiter plate, mixed with 0.03 μg ml⁻¹ mupirocin (0.5× MIC) and 50 μM test agent in Mueller-Hinton broth (MHB) (100-μl total well volume). Microtiter plates were incubated at 37°C for 16 h, and individual wells were inspected for growth. Wells lacking growth were considered to represent agents that either potentiated the antimicrobial properties of mupirocin or mupirocin-independent antimicrobial microbial properties. All drugs that resulted in no growth were confirmed in duplicate and were plated without mupirocin to measure their inherent antimicrobial activity.