Computing antimicrobial use/antimicrobial resistance ratios: A novel way to assess inpatient antimicrobial utilization using current National Healthcare Safety Network metrics.

BACKGROUND: Current methods for benchmarking inpatient antimicrobial use (AU) could benefit from combining AU with antimicrobial resistance (AR) information to provide metrics benchmarked to microbiological data; this may yield more instructive and better risk-adjusted measurements than AU and AR in isolation. METHODS: In this retrospective single-center study, we computed facility-wide AU/AR ratios from 2019 to 2020 for specific antimicrobial agents and corresponding AR events, and compared median monthly AU/AR ratios between March 2019 through December 2019 (pre-COVID period) and March 2020 through December 2020 (COVID period). Aggregate AU was expressed as a ratio to aggregate AR events for antimicrobials that typically have activity against the AR organism and are frequently used to treat the AR organism in clinical practice. We also computed AU/AR ratios in our surgical intensive care unit in the pre-COVID period. RESULTS: High-median facility-wide monthly AU/AR ratios were observed for intravenous vancomycin/methicillin-resistant Staphylococcus aureus, with 130.0 in the pre-COVID period and 121.3 in the COVID period (p =.520). Decreases in facility-wide median monthly AU/AR ratios were observed between periods for meropenem/ESBL Enterobacterales (20.9 vs. 7.9, p < .001), linezolid/vancomycin-resistant Enterococcus (48.5 vs. 15.8, p =.004), and daptomycin/vancomycin-resistant Enterococcus (32.2 vs. 4.8, p = .002). Increases in facility-wide median monthly AU/AR ratios were observed between periods for ceftazidime-avibactam/carbapenem-resistant Enterobacterales (0.0 vs. 3.2, p = .020) and ceftazidime-avibactam/multidrug-resistant Pseudomonas aeruginosa (0.0 vs. 4.0, p = .017). The AU/AR ratio for intravenous vancomycin/methicillin-resistant S. aureus in the surgical intensive care unit was 191.5 in the pre-COVID period. CONCLUSIONS: AU/AR ratios may be used to supplement current AU and AR metrics. Future directions should include the development of more AU metrics benchmarked to microbiological information. AU metrics more specific to transplant infectious diseases should be developed.

Emergence and rapid regional spread of Klebsiella pneumoniae carbapenemase-producing Enterobacteriaceae.

UNLABELLED: Exposure network analysis and molecular epidemiologic methods were used to analyze the emergence and regional spread of Klebsiella pneumoniae carbapenemase-producing Enterobacteriaceae over a 1-year period. Although 40 patients and 26 health care facilities were affected, 1 long-term acute care hospital played a critical role in the convergence of patients at high risk, amplification by cross-infection, and dissemination of these multidrug-resistant bacteria. BACKGROUND: Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae are an emerging antibiotic resistance threat with demonstrated epidemic potential. METHODS: We conducted an outbreak investigation of KPC-producing Enterobacteriaceae among patients of acute and long-term acute care hospitals (LTACHs) in 4 adjacent counties in Indiana and Illinois from 1 January 2008 through 31 December 2008 (cases). The study used traditional and molecular epidemiologic methods and an adaptation of social network analysis ("exposure network analysis"). RESULTS: Clinical records for 40 (95%) of 42 patients were available. Patients were mostly older with multiple comorbid conditions. Eleven patients (27.5%) died during the index hospitalization or were discharged to hospice; 23 (57.5%) were discharged to a nursing home, and 4 (10.0%) were discharged to home. One LTACH (LTACH-A) was central to the regional outbreak: 24 (60%) of 40 cases were linked to LTACH-A, and at least 10 patients (25%) acquired KPC there. Of 16 cases not linked to LTACH-A, 12 (75%) were linked to 3 nursing homes. Only 4 patients (10%) definitely acquired KPC during an acute care hospital stay. Molecular typing revealed the 31 available KPC-positive K. pneumoniae isolates to be similar and to cluster with epidemic multilocus sequence type 258; 2 KPC-positive Escherichia coli isolates were unique. CONCLUSIONS: We observed extensive transfer of KPC-positive patients throughout the exposure network of 14 acute care hospitals, 2 LTACHs, and 10 nursing homes. Although few cases were identified at most institutions, many facilities were affected. Successful control of KPC-producing Enterobacteriaceae will require a coordinated, regional effort among acute and long-term health care facilities and public health departments.