1109. Molecular Detection of Sepsis-Causing Pathogens Directly from Whole Blood Specimens
Session: Poster Abstract Session: Molecular and Nucleic Acid Testing Diagnostics
Friday, October 9, 2015
Room: Poster Hall
Background:

Fast and accurate detection of pathogens from patients with bloodstream infections (BSI) can be limited by a technology’s ability to detect low levels of microorganisms.  nanoMR has developed a Pathogen Capture System (PCS) as a clinical sample concentrator method to boost the sensitivity of molecular identification and resistance testing for whole blood specimens enabling detection of BSI in 3.5 hours. Since positivity rates of blood cultures (BC) are relatively low (<10%), we targeted blood collection from patients with known BSI and evaluated the performance of PCS and downstream molecular testing with BC. 

Methods:

The study was approved by Mayo Clinic, Rochester, MN IRB with informed consent. Five to 10 mL of blood were collected in vacutainers from patients within 24 - 48 hours of a positive BC.  Follow-up BC also were obtained by the same venipuncture.  Specimens were processed using PCS, a method based on proprietary immunomagnetic beads to capture and concentrate whole cells of ~ 20 pathogens directly from blood.  DNA was extracted by customized bead-based homogenization.  Pathogen identification was performed by species-specific qPCR using PrimerDesign Ltd. assays on the Roche LightCycler® 2.0 thermal cycler.

Results:

A total of 34 specimens (34 patients) were tested by PCS and species-specific qPCR.  Classification was determined by a standardized algorithm. Overall concordance with BC was 94%, including 2 indeterminate calls (Table 1).  The possibility of either case being the result of contamination during blood draw could not be discounted, yielding an indeterminate designation.

Table 1.

 Classification

Isolates

True Positive

7

True Negative

25

False Positive

0

False Negative

0

Indeterminate*

2

Percent Positive Agreement

88%

Percent Negative Agreement

96%

*1=Follow-up BC S. epidermidis and negative  nanoMR method.  1= Follow-up BC negative and nanoMR method S. epidermidis.

Conclusion:

nanoMR PCS is a novel, enabling technology that could greatly expand the application of molecular platforms for pathogen identification and resistance testing from whole blood specimens providing physicians timely information for targeted therapy.

Alexandra Barr, MS1, Edward Adams, PhD1, Lisa-Jo Clarizia, PhD1, Ruth Bauer, MS1, Stephen Springer, BS1, Michael Davila, BS1, Gerald Axford, BS1, Orlando Chavez, BS1, Victor Esch, PhD1, Robin Patel, MD, FIDSA, FRCP(C), D(ABMM), FACP, F(AAM)2, Cathy Petti, MD3 and Meghan Norvell, PhD1, (1)nanoMR, Albuquerque, NM, (2)Divisions Of Clinical Microbiology and Infectious Diseases, Mayo Clinic, Rochester, MN, (3)ARUP Laboratory, Salt Lake City, UT

Disclosures:

A. Barr, None

E. Adams, None

L. J. Clarizia, None

R. Bauer, None

S. Springer, None

M. Davila, None

G. Axford, None

O. Chavez, None

V. Esch, None

R. Patel, St. Jude, Thermo Fisher Scientific, Curetis: Consultant , Consulting fee
Pfizer, Pradama, Tornier, Astellas, Pocared, ECI Biotech, nanoMR, BioFire, Curetis, Check-Points, National Institutes of Health, 3M, Cubist, Hutchison Biofilm Medical Solutions, Accelerate Diagnostics (Instrument Evaluations: bioMérieux, Bruker, Abbott, N: Grant Investigator , Grant recipient
Mayo Clinic; Associate Editor’s Stipend for Journal of Clinical Microbiology: Employee , Salary
B. pertussisparapertussis PCR: Patent , Licensing agreement or royalty
Anti-biofilm substance,: Patent , None
Device/method for sonication: Patent , Licensing agreement to Mayo Clinic (not to Dr. Patel)

C. Petti, NanoMR: Consultant , Consulting fee

M. Norvell, None

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