A Single Hospital-Wide Antibiogram is Insufficient to Account for Differences in Antibiotic Resistance Patterns Across Multiple ICUs

Background Infection is a common cause of mortality within intensive care units (ICUs). Antibiotic resistance patterns and culture data are used to create antibiograms. Knowledge of antibiograms facilitates guiding empiric therapies and reduces mortality. Most major hospitals utilize data collection to create hospital-wide antibiograms. Previous studies have shown significant differences in susceptibility patterns between hospital wards and ICUs. We hypothesize that institutional or combined ICU antibiograms are inadequate to account for differences in susceptibility for patients in individual ICUs.Methods Culture and susceptibility data were reviewed over a 1-year period for 13 bacteria in the following ICUs: Surgical/Trauma, Medical, Neuroscience, Burn, and Emergency department. Antibiotic management decisions are made by individual teams.Results Nine species had sufficient data for inclusion into an All-ICU antibiogram. E coli and S aureus were the most common isolates. Seven species had significant differences in susceptibility patterns between ICUs. E cloacae showed higher rates of resistance to multiple antibiotics in the STICU than other ICUs. P aeruginosa susceptibility rates in the NSICU and BICU were 88% and 92%, respectively, compared to 60% and 55% in the STICU and MICU. Cephalosporins and Aztreonam had reduced efficacy against E coli in the NSICU, however remain effective in other ICUs.Conclusions The results of this study show that different ICUs do have variability in antibiotic susceptibility patterns within a single hospital. While this only represents a single institution, it shows that the use of hospital-wide antibiograms is inadequate for creating empiric antibiotic protocols within individual ICUs.