Document Type

Poster

Publication Date

2016

Abstract

Background:

Emergence of direct from positive blood culture bottle identification (ID) methods reveal opportunities for improving bacterial ID and select resistance marker detection turn-around-times. Each system has various advantages and disadvantages; each institution must select the method/s that best fit the laboratory and patient needs. Here we elucidate improvements in 24 hour workflow through incorporating multiple rapid technologies for positive blood culture ID into a 24 hour algorithm.

Methods:

MALDI-TOF (Bruker) analysis with sepsityper extraction (aerobic Gram-positive and anaerobic bacteria); MALDI-TOF analysis with serum separator tube concentration (Gram-negative bacteria); and a FilmArray Blood Culture Panel (Biofire) were utilized. MALDI was utilized on 1st shift for single bacterium positives. FilmArray was performed on 2nd and 3rd shift for aerobic bottles and on 1st shift for gram-positive cocci in clusters and Candida. We examined all events during our pre-modification (September-November 2013) and post-modification (late-December 2014-March 2015) time periods and defined an event as the first positive blood culture for a patient within the examined data period. The Antimicrobial Stewardship Pharmacist (ASP) was notified with identifications and also KPC carbapenemase positives, to implement a carbapenem-resistant Enterobacteriaceae (CRE) empiric treatment algorithm. For KPC positives (CRE) a custom minimum inhibitory concentration (MIC) panel was utilized, replacing a standard susceptibility panel and Etests. Finally, 2nd shift began susceptibility setup on subcultured bloods that had turned positive from 11 p.m.-6 a.m.

Results:

Pre- and post- workflow modification average turn-around times (TAT) and p-values are shown in the Table. Detection of either the KPC or the mecA marker significantly improved the TAT needed for phenotypic detection of carbapenem or methicillin resistance. KPC was detected in 3 Enterobactericeae.

Conclusions:

Improvements to patient care are to be determined, but strong collaboration with ASP is anticipated to make a significant impact on patient outcomes. Of note, while having a universal Staphylococcus species target is useful, it can lead to complications with multi-species positive bottles. With the universal Staphylococcus species target, it is not possible to differentiate between a mixed coagulase negative Staphylococcus species (CNSS) versus Staphylococcus aureus when both are present as the CNSS may harbor the mecA target, preventing adequate treatment. Furthermore, a Staphylococcus lugdunensis specific marker would be clinically useful.

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