178. The Reliability of the Nanosphere Verigene Gram-positive Panel for Use in an Antimicrobial Stewardship Program in a Pediatric Hospital
Session: Poster Abstract Session: Diagnostics: Bacteriology, Sequencing, and Resistance
Thursday, October 27, 2016
Room: Poster Hall
Background:Early intervention in bacteremia is critical to improve patient outcomes, reduce use of broad-spectrum antibiotics, and minimize length of inpatient stay. Advances in molecular testing of positive blood cultures have reduced time to pathogen and resistance gene identification. The Nanosphere Verigene Blood Culture Gram-Positive panel (BC-GP) detects 12 organisms and 3 resistance genes. Understanding how these rapid genotypic results compare to traditional phenotype allows Antimicrobial Stewardship Programs to best utilize this data to impact patient care.

Methods: All positive blood cultures with Gram-positive organisms seen on Gram-stained smears were tested with the Verigene BC-GP. All organisms were identified with MALDI-ToF and susceptibilities were determined with Vitek 2. Verigene BC-GP results were compared to the results from the MALDI-ToF and Vitek 2 over a two year period.

Results: From January 2014 through December 2015, 836 positive blood cultures were tested on the BC-GP: 141 S. aureus, 240 S. epidermidis, 107 other Staphylococcous species, 29 S. pneumoniae, 109 other Streptococcus species, 54 E. faecalis, 18 E. faecium, 1 Listeria species, 93 isolates not included in the BC-GP panel, 43 cultures in which there were multiple isolates, and one Staphyloccous species that did not grow in culture. Of the single isolate cultures containing organisms on the BC-GP panel, 499 were correctly identified to species, 166 to genus, 31 isolates were not detected, and 3 Streptococcus mitis/oralis were misidentified as Streptococcus pneumoniae.

Table: Resistance marker/phenotype agreement in single isolate cultures

Organism

Resistance Gene

Number Detected

% Concordant with Phenotype*

S. aureus

mecA +

59

98.3

S. aureus

mecA -

82

100

S. epidermidis

mecA +

74

97.3

S. epidermidis

mecA -

7

100

E. faecium

vanA/B +

5

100

E. faecium/ faecalis

vanA/B -

64

100

* Cohen’s kappa coefficient >0.8 for all genotype/phenotype comparisons

Conclusion: The Verigene BC-GP provides reliable organism and resistance gene identifications that correspond very closely with traditional phenotypic results. The reliability of the data coupled with the rapid turn-around time makes the Verigene BC-GP a useful tool for an active antimicrobial stewardship program.

Martina Beckman, MT1, Eleanor Powell, PhD1, David Haslam, MD2, Joshua Courter, PharmD3, Heidi Andersen, MD2, Matthew Washam, MD, MPH2, Barb Deburger, MT1 and Joel Mortensen, Ph.D.1, (1)Pathology and Laboratory Medicine, Cincinnati Children's Hospital, Cincinnati, OH, (2)Infectious Disease, Cincinnati Children's Hospital, Cincinnati, OH, (3)Division of Pharmacy, Cincinnati Children's Hospital Medical Center, Cincinnati, OH

Disclosures:

M. Beckman, None

E. Powell, None

D. Haslam, None

J. Courter, None

H. Andersen, None

M. Washam, None

B. Deburger, None

J. Mortensen, None

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