VANCOMYCIN-RESISTANT ENTEROCOCCUS-FAECIUM IN A VETERANS AFFAIRS MEDICAL-CENTER - ASSOCIATION WITH ANTIBIOTIC USAGE

Background: Colonization and infection with vancomycin-resistant Enter ococcus faecium (VREF) has been associated with the use of vancomycin and other antibiotics in individual patients, The objective of this st udy was to determine the association of VREF with the aggregate usage of antibiotics on nursing units in a hospital. Methods: This was a ret rospective correlation study A usage ratio was calculated for each par enteral antibiotic on each nursing unit as the per-bed usage by weight of that antibiotic divided by its average usage throughout the hospit al. An average usage ratio (AUR) for each nursing unit was calculated as the mean of usage ratios of individual antibiotics. The AUR was use d to compare the usage of antibiotics among nursing units in the hospi tal. The incidence of VREF: infections on individual nursing units in a Veterans Affairs Medical Center was correlated with the usage of par enteral antibiotics separately and in aggregate in uni-variate and mul tivariate regression analyses. Results: The AUR was strongly and posit ively correlated with the recovery of VREF on individual nursing units . By univariate analyses, increasing use of each antibiotic tested was associated with isolation of VREF but only clindamycin remained signi ficant in the multivariate model, However, usage of various antibiotic s was highly interrelated, and only clindamycin usage was significantl y correlated with usage of all other antibiotics studied. Intensive ca re and acute care units and units with fewer patient beds were more li kely to have patients with VREF infection than were subacute care unit s (p < 0.003) or larger units (p < 0.01). Conclusions: VREF infections were associated with greater aggregate antibiotic use on nursing unit s. Determination of antibiotic usage ratios may provide a convenient a nd useful tool for examining the association of antibiotic usage with other nosocomial infections.