Detection and Identification of Ehrlichia Species in Blood by Use of PCR and Electrospray Ionization Mass Spectrometry

• Published in: Journal of Clinical Microbiology Vol. 48; no. 2; pp. 472 - 478
• Main Authors: Eshoo, Mark W, Crowder, Chris D, Li, Haijing, Matthews, Heather E, Meng, Shufang, Sefers, Susan E, Sampath, Rangarajan, Stratton, Charles W, Blyn, Lawrence B, Ecker, David J, Tang, Yi-Wei
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.02.2010; American Society for Microbiology (ASM)
• Subjects: Bacteremia - diagnosis; Bacteremia - microbiology; Bacteriological Techniques - methods; Bacteriology; Biological and medical sciences; Blood - microbiology; Ehrlichia; Ehrlichia - chemistry; Ehrlichia - genetics; Ehrlichia - isolation & purification; Ehrlichiosis - diagnosis; Ehrlichiosis - microbiology; Fundamental and applied biological sciences. Psychology; Humans; Microbiology; Miscellaneous; Neisseria meningitidis; Neisseria meningitidis - isolation & purification; Polymerase Chain Reaction - methods; Predictive Value of Tests; Pseudomonas aeruginosa; Pseudomonas aeruginosa - isolation & purification; Rickettsia rickettsii; Rickettsia rickettsii - isolation & purification; Sensitivity and Specificity; Spectrometry, Mass, Electrospray Ionization - methods; Staphylococcus aureus; Staphylococcus aureus - isolation & purification; Time Factors; Ehrlichiaceae; Rickettsiales; Polymerase chain reaction; Bacteria; Ehrlichieae; Identification; Detection; Ehrlichia; Electrospray; Blood
• ISSN: 0095-1137; 1098-660X
• DOI: 10.1128/JCM.01669-09

Rapid detection and identification of Ehrlichia species improves clinical outcome for patients suspected of ehrlichiosis. We describe an assay that employs multilocus PCR and electrospray ionization mass spectrometry (PCR/ESI-MS) to detect and identify Ehrlichia species directly from blood specimens. The results were compared to those of a colorimetric microtiter PCR enzyme immunoassay (PCR-EIA) used as a diagnostic assay. Among 213 whole-blood samples collected from patients who were clinically suspected of ehrlichiosis from 1 May to 1 August 2008 at Vanderbilt University Hospital, 40 were positive for an Ehrlichia species by PCR/ESI-MS, giving a positive rate of 18.8%. In comparison to the PCR-EIA, PCR/ESI-MS possessed a sensitivity, a specificity, and positive and negative predictive values of 95.0%, 98.8%, 95.0%, and 98.8%, respectively. The 38 specimens that were positive for Ehrlichia by both PCR/ESI-MS and the PCR-EIA were further characterized to the species level, with 100% agreement between the two assays. In addition, Rickettsia rickettsii was detected by PCR/ESI-MS from four specimens that were confirmed retrospectively by serology and PCR-EIA. In three specimens, the PCR/ESI-MS assay identified Pseudomonas aeruginosa, Neisseria meningitidis, and Staphylococcus aureus; these were confirmed by culture and/or clinical diagnosis as being clinically relevant. From specimen processing to result reporting, the PCR/ESI-MS assay can be completed within 6 h, providing another laboratory tool for the diagnosis of ehrlichiosis. Moreover, this system may provide rapid detection and identification of additional pathogens directly from blood specimens.