Differences in antimicrobial susceptibility among hospitals in an integrated health system.

We evaluated the differences in antimicrobial susceptibility among hospitals in three different integrated healthcare systems. Each system provided antibiogram-susceptibility reports from representative hospitals. Reports were analyzed for statistically significant differences between hospitals in a given system for nine important organisms. We found numerous significant interhospital differences in antimicrobial-susceptibility patterns within health systems. For this reason, the practice of combining antibiotic-susceptibility data into a systemwide antibiogram should be discouraged.