Optimizing facility-specific urinary weighted-incidence syndromic antibiograms for nursing homes.

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Healthcare Epidemiology

Background:

• Nursing homes (NHs) face challenges in generating facility-specific urinary antibiograms due to low numbers of bacterial isolates.
• Standard Clinical and Laboratory Standards Institute (CLSI) methods are often insufficient for NH settings.

Purpose of the Study:

• To develop and evaluate an approach for creating facility-specific urinary antibiograms in NHs, addressing the issue of limited isolate recovery.
• To compare the performance of standard CLSI antibiogram models with various Weighted-Incidence Syndromic Antibiogram (WISCA) models.

Main Methods:

• Retrospective analysis of 5097 urine culture isolates from 59 NHs across five states (2020-2021).
• Comparison of a CLSI standard antibiogram model against four WISCA models with differing formatting rules.
• Evaluation of the ability to produce facility-specific antibiograms (≥30 isolates) and impact on susceptibility predictions.

Main Results:

• Only one NH could generate a CLSI antibiogram for common Gram-negative isolates using one year of data.
• WISCA models significantly increased antibiogram generation rates (36% to 85%) when using two years of data and all Gram-negative isolates.
• Changes in predicted antibiotic activity (e.g., ampicillin-sulbactam, cefazolin) were observed when using all Gram-negative isolates versus the top three pathogens.

Conclusions:

• Weighted-Incidence Syndromic Antibiogram (WISCA) models are superior to CLSI standards for NHs with low isolate counts.
• Utilizing two years of urinary culture data encompassing all Gram-negative isolates maximizes the number of NHs capable of generating valid facility-specific antibiograms.