Incidence and susceptibility or pathogenic bacteria vary between intensivecare units within a single hospital: Implications for empiric antibiotic strategies

Background: The purpose of this study was to determine whether the incidenc e of recovery and patterns of antibiotic susceptibility of pathogenic bacte ria vary between intensive care units (ICUs) in a single teaching hospital. Methods: Culture and susceptibility results were collected prospectively fo r a 3-month period (April through June 1999) in each of the surgical, traum a, and medical ICUs, The number of unique isolates and susceptibility patte rns were determined. Susceptibility of isolates among ICUs was compared wit h chi(2). Results: statistically significant differences between ICUs in susceptibili ty to various antibiotics were found for Staphylococcus aureus, Enterococcu s sp, Acinetobacter sp, Enterobacter sp, Klebsiella sp, and Pseudomonas sp, Notably, vancomycin-resistant Enterococcus was not seen in the medical ICU , whereas it was seen in both the surgical and trauma ICUs, Klebsiella spp resistant to ceftazidime were seen only in the trauma ICU, The aminoglycosi des and quinolones had attenuated activity against Pseudomonas sp in the su rgical ICU, whereas they remained highly effective in the trauma ICU. Cefaz olin had no activity against the Enterobacter sp in either of the surgical ICUs, but was highly effective in the medical ICU. Conclusion: Although the microbiologic results of this study should not be extrapolated to other institutions, the principle is of value. There is var iability between ICUs in a single large teaching hospital in susceptibility of bacterial pathogens to various antibiotics. This may have implications in the design of empiric antibiotic strategies and the planning of the hosp ital formulary. Hospital wide or composite ICU antibiograms are inadequate for planning empiric therapy in the ICU.