An Analysis of the Value-Added of Antibiogram Subgroup Stratification

BackgroundStratified antibiograms are recommended to guide empiric clinical treatment. However, which strata to focus on, the limited number of isolates in identified strata, and the heavy associated workload all pose challenges. This study compares differences in antibiotic susceptibility between a hospital-wide, all-specimens antibiogram and stratified antibiograms in order to identify the value-added of antibiogram stratification. MethodAntibiotic susceptibility of bacterial isolates from 2021 at a quaternary-care academic hospital was obtained from published hospital-wide and unit- and specimen-specific stratified antibiograms. Differences in percent susceptibility by organism and drug between the hospital-wide and stratified antibiograms were calculated. Weighted averages of the difference in percent susceptibility were calculated for each stratified antibiogram compared to the hospital-wide antibiogram and unit-wide antibiograms. Differences were shown through heat maps. ResultsWhen compared to a hospital-wide, all-specimens antibiogram, the emergency department (ED) antibiogram showed higher susceptibility, whereas intensive care unit (ICU) and, particularly, transplant unit (TR) antibiograms exhibited reduced susceptibility. Compared to ward level antibiograms, further stratification within each ward to specimen-specific (syndromic) antibiograms revealed additional differences. In ED, urine and respiratory-stratified antibiograms had lower susceptibility and blood had higher susceptibility. Compared to ward-specific antibiograms, in ICU, all specimen-stratified antibiograms had lower susceptibility and in transplant, antibiograms for all specimens but urine had lower susceptibility. ConclusionUsing a hospital-wide all-specimens antibiogram may both overcall and under call susceptibility leading to poor empiric antimicrobial choices. Specimen-specific antibiograms stratified by unit best inform empiric therapy for specific populations. SummaryUsing a hospital-wide all-specimens antibiogram may both overcall and under call susceptibility leading to poor empiric antimicrobial choices. There is value-added to providing combined unit-specific and specimen-specific antibiograms to help best inform empiric therapy for specific populations.