Does antimicrobial resistance cluster in individual hospitals?

Factors that affect the resistance rates for an organism-drug combination in a given hospital also might influence resistance rates for other organism-drug combinations. We examined correlations between resistance prevalence in non-intensive care inpatient areas of 41 hospitals participating in phase 3 (1998-1999) of Project ICARE (Intensive Care Antimicrobial Resistance Epidemiology). We focused on statistically significant (P<.05) Pearson correlation coefficients for methicillin-resistant Staphylococcus aureus, coagulase-negative staphylococci, vancomycin-resistant enterococci, and resistance to third-generation cephalosporins, imipenem, and fluoroquinolones in Escherichia coli, Klebsiella pneumoniae, Enterobacter species, and Pseudomonas aeruginosa. Resistance prevalence rates in individual hospitals were not strongly correlated among gram-positive organisms, and few correlations were seen between rates in gram-positive and gram-negative organisms. More frequent significant associations were found among resistance rates for gram-negative organisms. Resistance to third-generation cephalosporins in K. pneumoniae was significantly correlated with the majority of other sentinel antimicrobial-resistant organisms. High prevalence of this organism may serve as a marker for more generalized resistance problems in hospital inpatient areas.