A geospatial approach to identify patterns of antibiotic susceptibility at a neighborhood level in Wisconsin, United States

Abstract

The global threat of antimicrobial resistance (AMR) varies regionally. This study explores whether geospatial analysis and data visualization methods detect both clinically and statistically significant variations in antibiotic susceptibility rates at a neighborhood level. This observational multicenter geospatial study collected 10 years of patient-level antibiotic susceptibility data and patient addresses from three regionally distinct Wisconsin health systems (UW Health, Fort HealthCare, Marshfield Clinic Health System [MCHS]). We included the initial Escherichia coli isolate per patient per year per sample source with a patient address in Wisconsin (N = 100,176). Isolates from U.S. Census Block Groups with less than 30 isolates were excluded (n = 13,709), resulting in 86,467 E. coli isolates. The primary study outcomes were the results of Moran's I spatial autocorrelation analyses to quantify antibiotic susceptibility as spatially dispersed, randomly distributed, or clustered by a range of - 1 to + 1, and the detection of statistically significant local hot (high susceptibility) and cold spots (low susceptibility) for variations in antibiotic susceptibility by U.S. Census Block Group. UW Health isolates collected represented greater isolate geographic density (n = 36,279 E. coli, 389 = blocks, 2009-2018), compared to Fort HealthCare (n = 5110 isolates, 48 = blocks, 2012-2018) and MCHS (45,078 isolates, 480 blocks, 2009-2018). Choropleth maps enabled a spatial AMR data visualization. A positive spatially-clustered pattern was identified from the UW Health data for ciprofloxacin (Moran's I = 0.096, p = 0.005) and trimethoprim/sulfamethoxazole susceptibility (Moran's I = 0.180, p < 0.001). Fort HealthCare and MCHS distributions were likely random. At the local level, we identified hot and cold spots at all three health systems (90%, 95%, and 99% CIs). AMR spatial clustering was observed in urban areas but not rural areas. Unique identification of AMR hot spots at the Block Group level provides a foundation for future analyses and hypotheses. Clinically meaningful differences in AMR could inform clinical decision support tools and warrants further investigation for informing therapy options.

Figure 1

Wisconsin study areas included and excluded in analysis*. Isolate counts less than and greater than 30 isolates by U.S. Census Block Groups for each health system are shown. Block Groups with at least 30 isolates were included in the analysis. Figure created with ArcGIS Pro software (Version 2.7; ESRI, Redlands, California, https://www.esri.com/en-us/arcgis/products/arcgis-pro/overview). *This geographic data presentation is considered ‘de-identified’ by ‘Expert determination’ under the HIPAA Privacy rule.

Figure 2

Marshfield Clinic Health System ciprofloxacin and sulfamethoxazole/trimethoprim susceptibility choropleth (noncontiguous areas included)^a and hot spot analysis results (Contiguous edge only)^b*. ^aColored polygons show U.S. Census Block Groups by three categories of E. coli percent susceptibility to two antibiotics. All included Block Groups have at least 30 isolates. ^bColored polygons show U.S. Census Block Groups that have statistically significant variation in antibiotic susceptibility. Blue cold spots show U.S. Census Block Groups with low susceptibility. Red hots spots show U.S. Census Block Groups with high antibiotic susceptibility. Hot spot analysis incorporates how each polygon relates to the mean antibiotic susceptibility and surrounding polygons (spatial dependencies). The color scale within the red hot-spots and blue cold-spots shows categories of statistical confidence. All included Block Groups have at least 30 isolates. Figures created with ArcGIS Pro software (Version 2.7; ESRI, Redlands, California, https://www.esri.com/en-us/arcgis/products/arcgis-pro/overview). *This geographic data presentation is considered ‘de-identified’ by ‘Expert determination’ under the HIPAA privacy rule.

Figure 3

UW Health ciprofloxacin and sulfamethoxazole/trimethoprim susceptibility choropleth (noncontiguous areas included)^a and hot spot analysis results (Contiguous edge only)^b*. ^aColored polygons show Block Groups by three categories of E. coli percent susceptibility to two antibiotics. All included Block Groups have at least 30 isolates. ^bColored polygons show Block Groups that have statistically significant variation in antibiotic susceptibility. Blue cold spots show Block Groups with low susceptibility. Red hots spots show Block Groups with high antibiotic susceptibility. Hot spot analysis incorporates how each polygon relates to the mean antibiotic susceptibility and surrounding polygons (spatial dependencies). The color scale within the red hot-spots and blue cold-spots shows categories of statistical confidence. All included Block Groups have at least 30 isolates included. Figures created with ArcGIS Pro software (Version 2.7; ESRI, Redlands, California, https://www.esri.com/en-us/arcgis/products/arcgis-pro/overview). *This geographic data presentation is considered ‘de-identified’ by ‘Expert determination’ under the HIPAA privacy rule.

Figure 4

Fort healthcare ciprofloxacin and sulfamethoxazole/trimethoprim susceptibility choropleth (noncontiguous areas included)^a and hot spot analysis results (Contiguous edge only)^b*. ^aColored polygons show Block Groups by three categories of E. coli percent susceptibility to two antibiotics. All included Block Groups have at least 30 isolates. ^bColored polygons show Block Groups that have statistically significant variation in antibiotic susceptibility. Blue cold spots show Block Groups with low susceptibility. Red hots spots show Block Groups with high antibiotic susceptibility. Hot spot analysis incorporates how each polygon relates to the mean antibiotic susceptibility and surrounding polygons (spatial dependencies). The color scale within the red hot-spots and blue cold-spots shows categories of statistical confidence. All included Block Groups have at least 30 isolates. Figures created with ArcGIS Pro software (Version 2.7; ESRI, Redlands, California, https://www.esri.com/en-us/arcgis/products/arcgis-pro/overview). *This geographic data presentation is considered ‘de-identified’ by ‘Expert determination’ under the HIPAA privacy rule.