Yvan Caspar1,2, Cécile Garnaud2,3, Mariya Raykova3, Sébastien Bailly3,4, Marie Bidart5,6,7, Danièle Maubon2,3. 1. Laboratoire de Bactériologie-Hygiène Hospitalière, Département des Agents Infectieux, Institut de Biologie et de Pathologie, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France. 2. Laboratoire TIMC-IMAG-TheREx, UMR 5525 CNRS-UGA, Université Grenoble Alpes, La Tronche Cedex, France. 3. Laboratoire de Parasitologie-Mycologie, Département des Agents Infectieux, Institut de Biologie et de Pathologie, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France. 4. INSERM UMR 1137 IAME Team 5-DeSCID, Inserm/Paris Diderot, Sorbonne Paris Cité University, Paris, France. 5. Plateforme Protéomique et Transcriptomique Clinique, Pôle Recherche, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France. 6. INSERM UMR 1205, Université Grenoble Alpes, Grenoble, France. 7. Laboratoire de Biochimie génétique et Moléculaire, Département de Biochimie, Toxicologie et Pharmacologie Institut de Biologie et de Pathologie, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France.
Abstract
PURPOSE: Fast species diagnosis has an important health care impact, as rapid and specific antibacterial therapy is of clear benefit for patient's outcome. Here, a new protocol for species identification directly from positive blood cultures is proposed. EXPERIMENTAL DESIGN: Four in-house protocols for bacterial identification by MS directly from clinical positive blood cultures evaluating two lytic agents, SDS and saponin, and two protein extraction schemes, fast (FP) and long (LP) are compared. One hundred and sixty-eight identification tests are carried out on 42 strains. RESULTS: Overall, there are correct identifications to the species level in 90% samples for the SDS-LP, 60% for the SDS-FP, 48% for the saponin LP, and 43% for the saponin FP. Adapted scores allowed 92, 86, 72, and 53% identification for SDS-LP, SDS-FP, saponin LP, and saponin FP, respectively. Saponin lysis is associated with a significantly lower score compared to SDS (0.87 [0.83-0.92], p-value < 0.001). CONCLUSIONS AND CLINICAL RELEVANCE: This study supports the use of SDS lysis instead of saponin lysis and the application of this rapid and cost-effective protocol in daily routine for microbiological agents implicated in septicemia.
PURPOSE: Fast species diagnosis has an important health care impact, as rapid and specific antibacterial therapy is of clear benefit for patient's outcome. Here, a new protocol for species identification directly from positive blood cultures is proposed. EXPERIMENTAL DESIGN: Four in-house protocols for bacterial identification by MS directly from clinical positive blood cultures evaluating two lytic agents, SDS and saponin, and two protein extraction schemes, fast (FP) and long (LP) are compared. One hundred and sixty-eight identification tests are carried out on 42 strains. RESULTS: Overall, there are correct identifications to the species level in 90% samples for the SDS-LP, 60% for the SDS-FP, 48% for the saponin LP, and 43% for the saponin FP. Adapted scores allowed 92, 86, 72, and 53% identification for SDS-LP, SDS-FP, saponin LP, and saponin FP, respectively. Saponin lysis is associated with a significantly lower score compared to SDS (0.87 [0.83-0.92], p-value < 0.001). CONCLUSIONS AND CLINICAL RELEVANCE: This study supports the use of SDS lysis instead of saponin lysis and the application of this rapid and cost-effective protocol in daily routine for microbiological agents implicated in septicemia.
Authors: Luke W Anson; Kevin Chau; Nicholas Sanderson; Sarah Hoosdally; Phelim Bradley; Zamin Iqbal; Hang Phan; Dona Foster; Sarah Oakley; Marcus Morgan; Tim E A Peto; Derrick W Crook; Louise J Pankhurst Journal: J Med Microbiol Date: 2018-01-10 Impact factor: 2.472