title: The IRIDICA PCR/Electrospray Ionization-Mass Spectrometry Assay on Bronchoalveolar Lavage for Bacterial Etiology in Mechanically Ventilated Patients with Suspected Pneumonia.
abstract: We studied the diagnostic performance of the IRIDICA PCR/electrospray ionization-mass spectrometry (PCR/ESI-MS) assay applied on bronchoalveolar lavage (BAL) samples, from 51 mechanically ventilated patients with suspected pneumonia, in a prospective study. In 32 patients with X-ray verified pneumonia, PCR/ESI-MS was positive in 66% and BAL culture was positive in 38% (p = 0.045), and either of the methods was positive in 69%. The following BAL result combinations were noted: PCR/ESI-MS+/culture+, 34%; PCR/ESI-MS+/culture-, 31%; PCR/ESI-MS-/culture+, 3.1%; PCR/ESI-MS-/culture-, 31%; kappa 0.36 (95% confidence interval (CI), 0.10-0.63). In pneumonia patients without prior antibiotic treatment, optimal agreement was noted with 88% PCR/ESI-MS+/culture+ and 12% PCR/ESI-MS-/culture- (kappa 1.0). However, in patients with prior antibiotic treatment, the test agreement was poor (kappa 0.16; 95% CI, -0.10-0.44), as 10 patients were PCR/ESI-MS+/culture-. In 8/10 patients the pathogens detected by PCR/ESI-MS could be detected by other conventional tests or PCR tests on BAL. Compared with BAL culture, PCR/ESI-MS showed specificities and negative predictive values of ≥87% for all individual pathogens, an overall sensitivity of 77% and positive predictive value (PPV) of 42%. When other conventional tests and PCR tests were added to the reference standard, the overall PPV increased to 87%. The PCR/ESI-MS semi-quantitative level tended to be higher for PCR/ESI-MS positive cases with pneumonia compared with cases without pneumonia (p = 0.074). In conclusion, PCR/ESI-MS applied on BAL showed a promising performance and has potential to be clinically useful in mechanically ventilated patients with suspected pneumonia. The usefulness of the method for establishment of pneumonia etiology and selection of antibiotic therapy should be further studied.
authors.affiliation: Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden.|Unit of Infectious Diseases, Department of Medicine Huddinge, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Kristoffer
authors.identifier: http://orcid.org/0000-0002-8801-3169
authors.initials: K
authors.lastname: Strålin
authors.affiliation: Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Ehn
authors.affiliation: Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden.|Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Christian G
authors.initials: CG
authors.lastname: Giske
authors.affiliation: Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden.|Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Måns
authors.initials: M
authors.lastname: Ullberg
authors.affiliation: Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden.|Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Hedlund
authors.affiliation: Department of Anesthesiology and Intensive Care, Karolinska University Hospital Solna, Stockholm, Sweden.|Section of Anaesthesiology and Intensive Care Medicine, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Petersson
authors.affiliation: Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden.|Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Carl
authors.initials: C
authors.lastname: Spindler
authors.affiliation: Department of Clinical Microbiology, Karolinska University Hospital, Stockholm, Sweden.|Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Volkan
authors.initials: V
authors.lastname: Özenci
mesh_terms: D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology*; D016022:Case-Control Studies; D006801:Humans; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D011014:Pneumonia / Q000382:microbiology* / Q000473:pathology / Q000628:therapy; D016133:Polymerase Chain Reaction / Q000379:methods; D012121:Respiration, Artificial; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*