BACKGROUND: CRE has been reportable in Tennessee since 2011; isolates must be sent to the State Public Health Laboratory (SPHL) to confirm carbapenemase production and for resistance mechanism testing (blaKPC, and blaNDM). Regional situational awareness of CRE is an important component to improve regional response to this urgent threat.
METHODS: CRE are defined as E.coli, Klebsiella, and Enterobacter species isolated from any clinical specimen and resistant to doripenem, meropenem, imipenem (minimum inhibitory concentrations [MIC] of ≥4 µg/ml) or ertapenem (MIC ≥2 µg/ml, or demonstrated production of a carbapenemase. We compared reports from the first 8 months of 2015 and 2016. County of residency and county level aggregate data were analyzed using SAS V9.4 and displayed in iDashboard (a visual tool that allows interactive portrayal of data).
RESULTS: In the first eight months of 2015 240 cases of CRE were reported, 57 (24%) of which were carbapenemase-producing (CP-CRE) compared to 475 cases, 130 (27%) in 2016, an increase of 49% and 56%. In 2015, species included 82 (34%) Enterobacter, 98 (41%) E. coli, and 60 (25%) Klebsiella. Similar to that in 2016-- 185 (39%) Enterobacter, 149 (31%) E. coli, and 141 (30%) Klebsiella. The predominant CP-CRE in 2016 was Klebsiella (50%), whereas it was Enterobacter (49%) in 2015 . The iDashboard highlights CP-CRE hotspots in Southwestern (SW) and Northeastern (NE) TN. In 2015 and 2016, Shelby County (Memphis), in SW TN, primarily harbored CP-CRE Enterobacter; n=20 (87%) and n=28 (76%). Over one year, NE TN evolved from few reported CP-CRE to become a hotspot of Klebsiella CP-CRE with some counties showing incidences as high as 15 cases/100,000 person-years (p-y). Davidson county (Nashville) reported no CP-CRE in 2015 and two CP-CRE cases in 2016. The mean annualized incidence rate of CRE was 2.80 and 5.02 cases/100,000 p-y for 2015 and 2016 respectively. An exact sign test was used to test the significance of the increase; a 2.23 cases/100,000 p-y mean increase was observed in annualized incidence rate in 2016 (p<0.0001). Similarly, CP-CRE showed a mean increase of 1.61 cases/100,000 p-y from 2015 (0.84) to 2016 (2.45) (p=0.0009).
CONCLUSIONS: CRE and CP-CRE incidence continues to rapidly increase across Tennessee with remarkable geographic variation. iDashboard is a visual tool used to interactively portray CRE data. The interactive maps within iDashboard can improve situational awareness of CRE and improve regional response to this urgent threat.