title: Improved sensitivity for molecular detection of bacterial and Candida infections in blood.
abstract: The rapid identification of bacteria and fungi directly from the blood of patients with suspected bloodstream infections aids in diagnosis and guides treatment decisions. The development of an automated, rapid, and sensitive molecular technology capable of detecting the diverse agents of such infections at low titers has been challenging, due in part to the high background of genomic DNA in blood. PCR followed by electrospray ionization mass spectrometry (PCR/ESI-MS) allows for the rapid and accurate identification of microorganisms but with a sensitivity of about 50% compared to that of culture when using 1-ml whole-blood specimens. Here, we describe a new integrated specimen preparation technology that substantially improves the sensitivity of PCR/ESI-MS analysis. An efficient lysis method and automated DNA purification system were designed for processing 5 ml of whole blood. In addition, PCR amplification formulations were optimized to tolerate high levels of human DNA. An analysis of 331 specimens collected from patients with suspected bloodstream infections resulted in 35 PCR/ESI-MS-positive specimens (10.6%) compared to 18 positive by culture (5.4%). PCR/ESI-MS was 83% sensitive and 94% specific compared to culture. Replicate PCR/ESI-MS testing from a second aliquot of the PCR/ESI-MS-positive/culture-negative specimens corroborated the initial findings in most cases, resulting in increased sensitivity (91%) and specificity (99%) when confirmed detections were considered true positives. The integrated solution described here has the potential to provide rapid detection and identification of organisms responsible for bloodstream infections.
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Bacconi
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA.
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Richmond
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Baroldi
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Laffler
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA.
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Blyn
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Carolan
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Frinder
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA.
authors.forename: Donna M
authors.initials: DM
authors.lastname: Toleno
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA.
authors.forename: David
authors.initials: D
authors.lastname: Metzgar
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA.
authors.forename: Jose R
authors.initials: JR
authors.lastname: Gutierrez
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Massire
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA.
authors.forename: Megan
authors.initials: M
authors.lastname: Rounds
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA.
authors.forename: Natalie J
authors.initials: NJ
authors.lastname: Kennel
authors.affiliation: Department of Emergency Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Rothman
authors.affiliation: Department of Emergency Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Peterson
authors.affiliation: The Johns Hopkins Hospital Clinical Microbiology Laboratory, Baltimore, Maryland, USA.
authors.forename: Karen C
authors.initials: KC
authors.lastname: Carroll
authors.affiliation: The Johns Hopkins Hospital Clinical Microbiology Laboratory, Baltimore, Maryland, USA.
authors.forename: Teresa
authors.initials: T
authors.lastname: Wakefield
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Ecker
authors.affiliation: Ibis Biosciences, Inc., Carlsbad, California, USA rangarajan.sampath@abbott.com.
authors.forename: Rangarajan
authors.identifier: http://orcid.org/0000-0002-2951-6372
authors.initials: R
authors.lastname: Sampath
mesh_terms: D000293:Adolescent; D000328:Adult; D057205:Automation, Laboratory / Q000379:methods; D016470:Bacteremia / Q000175:diagnosis*; D001769:Blood / Q000382:microbiology*; D058387:Candidemia / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D016133:Polymerase Chain Reaction / Q000379:methods*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D055815:Young Adult