832. A Broad-Range Polymerase Chain Reaction Coupled to Electrospray Ionization Mass Spectrometry for Detection of Biothreat Agents and Common Pathogens in Respiratory Samples
Session: Oral Abstract Session: Advances in Diagnostics
Saturday, October 22, 2011: 8:45 AM
Room: 151AB
Background: Biological threat (BT) agent infections (i.e. Anthrax, Plague, and Tularemia) often present with symptoms similar to other common respiratory infections (i.e. influenza like illness). New diagnostic platforms for respiratory pathogens must be capable of sensitive, specific, and rapid differentiation of BT organisms and common pathogens from normal flora.  Base composition characterization by electrospray ionization mass spectrometry (ESI-MS) of nucleic acids amplified via RT-PCR from human respiratory samples allows for broad pathogen identification within eight hours after collection.  In this study, we investigated the performance characteristics of RT-PCR/ESI-MS for distinguishing BT agents and common bacterial, fungal, and viral respiratory pathogens from normal flora in clinical samples from subjects with suspected respiratory infections.

Methods: Bronchoalveolar lavages (BALs) and nasopharyngeal (NP) swab samples were collected from patients with acute respiratory infections seen at the Johns Hopkins Hospital from July 2010 – April 2011.  Samples were processed using standard laboratory procedures for routine clinical care; residual specimens were archived. The archived samples were extracted and either used as controls or spiked with DNA from BT organisms and analyzed by RT-PCR/ESI-MS assays for the detection of BT and clinically relevant bacterial, fungal, and viral respiratory pathogens.  Assay data was compared to established clinical protocols or mock-up sequence to determine assay performance characteristics. 

Results: Sensitivity and specificity of RT-PCR/ESI-MS versus gold standard clinical methods was as follows for the 138 BALs and 45 NPs processed to date (82 bacterial, 24 viral, 12 fungal pathogens):

Pathogen

Sensitivity

Specificity

BT DNA spike

100%  (95% CI: 80.7 - 100.0)

100%  (95% CI: 88.3 - 100.0)

Bacterial pathogens

89.0% (95% CI: 79.7 – 94.5)

90.4% (95% CI: 81.3 – 95.4)

Fungal pathogens

90.9% (95% CI: 57.1 - 99.5)

97.6% (95% CI: 86.2 - 99.9)

Viral pathogens

95.5% (95% CI: 75.1 - 99.7)

97.0% (95% CI: 90.8 - 99.2)

Conclusion: The RT-PCR/ESI-MS platform demonstrated sensitive and specific detection of BT DNA and common pathogens in respiratory samples. 


Subject Category: D. Diagnostic microbiology

Kevin Jeng, B.S.1, Richard Rothman, MD, PhD2, Helen Won, MS3, Lawrence Blyn, PhD4, Ranga Sampath, PhD4, Stephen Peterson, MS3, Karen Carroll, MD, FIDSA5 and Charlotte Gaydos, DrPH1, (1)Medicine, Infectious Diseases, Johns Hopkins University, Baltimore, MD, (2)Johns Hopkins Medical Institute, Baltimore, MD, (3)Johns Hopkins School of Medicine, Baltimore, MD, (4)Ibis Biosciences, Inc., A Division of Abbott, Carlsbad, CA, (5)Medical Microbiology, Johns Hopkins Hospital, Baltimore, MD

Disclosures:

K. Jeng, None

R. Rothman, Ibis Biosciences: Grant Investigator, Grant recipient

H. Won, None

L. Blyn, Ibis Biosciences: Employee, Salary

R. Sampath, Ibis Biosciences: Employee, Salary

S. Peterson, None

K. Carroll, Quidel, Inc.: Consultant, Consulting fee
NanoMR: Consultant, Consulting fee
BD Diagnostics, Inc: Research Contractor, Research support

C. Gaydos, Ibis Biosciences: Grant Investigator, Grant recipient

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.