Abstract
ABSTRACTThe use of molecular-based diagnostic testing, such as the Luminex Verigene system, to rapidly identify the most common bacterial isolates from blood cultures is an important tool that reduces the duration of inappropriate antibiotics and decreases mortality. However, 5 to 15% of microorganisms recovered from blood culture are unable to be identified by the Verigene Gram-negative (BC-GN) or Gram-positive (BC-GP) assays. In this retrospective, observational study, we evaluate the identities and antimicrobial susceptibility patterns of 229 isolates that were not identified by either the Verigene BC-GN or BC-GP assay. The results presented here suggest that important, clinically relevant information about antimicrobial susceptibility patterns can still be inferred even when isolates are not identified by Verigene. We also examined changes in antibiotic use for patients with “unidentified” Verigene results at our institution and found that this subgroup represents an opportunity to optimize empirical antibiotic therapy.IMPORTANCE Rapid diagnostic testing to identify bloodstream pathogens has arisen as an important tool both to ensure adequate antimicrobial therapy is given early and to aid in antimicrobial stewardship by allowing for more rapid deescalation of inappropriate antimicrobial therapy. However, there is a paucity of data regarding the significance of isolates that are not able to be identified by rapid diagnostic testing. In this study, we report the identification to the species level and antimicrobial susceptibilities among isolates that were not identified by one such rapid diagnostic platform, the Verigene system. This study provides important insight into how a strong understanding of the strengths and limitations of a given rapid diagnostic platform, coupled with insight into local antibiotic susceptibility patterns, can allow for more nuanced and thoughtful empirical antibiotic selection.
Highlights
IMPORTANCE Rapid diagnostic testing to identify bloodstream pathogens has arisen as an important tool both to ensure adequate antimicrobial therapy is given early and to aid in antimicrobial stewardship by allowing for more rapid deescalation of inappropriate antimicrobial therapy
Multiple studies have shown that the use of Verigene significantly reduces the duration of inappropriate antibiotics and expedites the time to optimal antibiotic therapy [6, 11, 15,16,17] and leads to decreased mortality, when it is combined with guidance from an antimicrobial stewardship program (ASP) [12, 13, 18]
In this study, we characterized the blood culture isolates not identified by Verigene using real-world clinical microbiology laboratory results
Summary
IMPORTANCE Rapid diagnostic testing to identify bloodstream pathogens has arisen as an important tool both to ensure adequate antimicrobial therapy is given early and to aid in antimicrobial stewardship by allowing for more rapid deescalation of inappropriate antimicrobial therapy. The presence of a resistance mechanism is only reported when an organism is correctly identified, This combination of species and genera includes the most common bacteria isolated from the bloodstream [19,20,21], which allows the Verigene system to identify most clinical bloodstream isolates. This has been confirmed by multiple clinical studies in which Verigene correctly identifies isolates recovered from blood cultures to the genus or even species level greater than 90% of the time [8,9,10, 22,23,24,25,26,27,28]. The Verigene system performs significantly better with monomicrobial cultures, with estimates of accuracy for polymicrobial cultures ranging from approximately 50 to 70% for Gram-negative organisms and 60 to 75% for Gram-positive organisms [8, 9, 14, 23, 28,29,30,31]
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