FcMBL magnetic bead-based MALDI-TOF MS rapidly identifies paediatric blood stream infections from positive blood cultures

• Published in: PloS one Vol. 17; no. 11; p. e0276777
• Main Authors: Kite, Kerry Anne, Loomba, Sahil, Elliott, Thomas J, Yongblah, Francis, Lightbown, Shanda L, Doyle, Thomas J, Gates, Lily, Alber, Dagmar, Downey, George A, McCurdy, Michael T, Hill, James A, Super, Michael, Ingber, Donald E, Klein, Nigel, Cloutman-Green, Elaine
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 22-11-2022; Public Library of Science (PLoS)
• Subjects: Automation; Bacteremia; Bacteremia - diagnosis; Bacteremia - microbiology; Bacteria; Bacterial infections; Bacteriological Techniques - methods; Beads; Binding; Biology and Life Sciences; Blood; Blood Culture; Candidemia; Carbon dioxide; Centrifugation; Child; Diagnosis; E coli; Fungi; Gram-negative bacteria; Gram-Positive Bacteria; Health aspects; Humans; Identification; Identification methods; Infections; Inoculation; Lectins; Liquid culture; Magnetic Phenomena; Mannose; Mannose-binding lectin; Mass spectrometry; Mass spectroscopy; Medical examination; Medicine and Health Sciences; Pathogens; Pediatrics; Physical Sciences; Proteins; Research and Analysis Methods; Sensitivity; Sepsis; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods; Time-of-flight mass spectrometry; Yeast; United Kingdom; United Kingdom > UK
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0276777

Rapid identification of potentially life-threatening blood stream infections (BSI) improves clinical outcomes, yet conventional blood culture (BC) identification methods require ~24-72 hours of liquid culture, plus 24-48 hours to generate single colonies on solid media suitable for identification by mass spectrometry (MS). Newer rapid centrifugation techniques, such as the Bruker MBT-Sepsityper® IVD, replace culturing on solid media and expedite the diagnosis of BCs but frequently demonstrate reduced sensitivity for identifying clinically significant Gram-positive bacterial or fungal infections. This study introduces a protocol that utilises the broad-range binding properties of an engineered version of mannose-binding lectin linked to the Fc portion of immunoglobulin (FcMBL) to capture and enrich pathogens combined with matrix-assisted laser desorption-ionisation time-of-flight (MALDI-TOF) MS for enhanced infection identification in BCs. The FcMBL method identified 94.1% (64 of 68) of clinical BCs processed, with a high sensitivity for both Gram-negative and Gram-positive bacteria (94.7 and 93.2%, respectively). The FcMBL method identified more patient positive BCs than the Sepsityper® (25 of 25 vs 17 of 25), notably with 100% (3/3) sensitivity for clinical candidemia, compared to only 33% (1/3) for the Sepsityper®. Additionally, during inoculation experiments, the FcMBL method demonstrated a greater sensitivity, identifying 100% (24/24) of candida to genus level and 9/24 (37.5%) top species level compared to 70.8% (17/24) to genus and 6/24 to species (25%) using the Sepsityper®. This study demonstrates that capture and enrichment of samples using magnetic FcMBL-conjugated beads is superior to rapid centrifugation methods for identification of BCs by MALDI-TOF MS. Deploying the FcMBL method therefore offers potential clinical benefits in sensitivity and reduced turnaround times for BC diagnosis compared to the standard Sepsityper® kit, especially for fungal diagnosis.