Microbiology Labs Play an Important Role in Antimicrobial Stewardship

Antimicrobial susceptibility test
Antimicrobial susceptibility test
Microbiology labs play an important role in antimicrobial stewardship and resistance monitoring, but are underused.

Microbiology labs play an important role in antimicrobial stewardship programs (ASPs) and in monitoring antimicrobial resistance but are underused, according to a study presented at IDWeek 2016 in New Orleans, Louisiana.

James A. McKinnell, MD, of the Infectious Disease Clinical Outcomes Research (ID-CORE) unit at Harbor-UCLA Medical Center in Torrance, California, and colleagues gathered data from the California Antimicrobial Resistance Laboratory Network Assessment (CARLA), a voluntary, cross-sectional survey given to microbiology staff in California acute care hospitals.

Survey respondents were asked about antibiogram development and selective reporting at their respective hospitals. The researchers used the National Healthcare Safety Network 2015 Annual Survey to determine patient volume data and number of hospital beds. The response rate was 73% from Los Angeles County vs 67% statewide.

A total of 264 hospitals were included in the survey, reflecting 75% of all hospital beds in California.  Respondents were laboratory directors (n=165), clinical lab scientists (n=97), and infection preventionists (n=2). Seventy-eight percent (205) of respondents reported preparing an antibiogram for their institution.

Of the 224 hospitals whose labs had the ability to selectively report susceptibility results, 38% (99) suppress carbapenem results for Escherichia coli susceptible to ceftriaxone; 21% (56) for Pseudomonas aeruginosa susceptible to cefepime/ceftazidime/piperacillin-tazobactam, and 19% (50) for Acinetobacter spp susceptible to ceftazidime.

“Among 182 (69%) with access to carbapenemase tests, 80 (44%) edit all β-lactam results to resistant if a carbapenemase is detected. Ninety-eight (37%) hospitals develop population-specific antibiograms, including inpatient vs outpatient and ICU vs ward; 101 (38%) create source-specific antibiograms,” researchers said, which included 90 for urine, 29 for blood, and 10 for respiratory.

“Antimicrobial stewardship programs are by definition a collaborative process to improve antibiotic use in the facility,” Dr McKinnell said in an interview with Infectious Disease Advisor. “Unfortunately, far too often, the importance of the microbiologist is overlooked.” Dr McKinnell explained that the simplest and most essential intervention for stewardship programs is “selective or ‘cascade’ reporting.  By not releasing the culture results for specific antibiotics, physicians will change therapy to an antibiotic without susceptibility results. It is one of the least invasive, but also very effective, interventions for any stewardship program. Unfortunately, relatively few hospitals even consider attempting cascade reporting.  Even when cascade reporting is done, the methods are not ideal,” he said.

“The majority of California hospitals have access to laboratories with selective reporting capabilities, and their ASP should consider incorporating this practice. Similarly, ASPs can further engage their microbiology labs to produce stratified antibiograms,” the researchers concluded.

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McKinnell JA, Epson E, Horwich-Scholefield S, et al. The microbiology laboratory is a valuable, but largely underutilized partner in antimicrobial stewardship and antimicrobial resistance monitoring. Presented at: IDWeek 2016. New Orleans, LA; October 26-30, 2016. Poster 970.