Interlaboratory comparison of phage susceptibility testing.
Krupa Parmar, Lauren Komarow, Damon W Ellison, Andrey A Filippov, Mikeljon P Nikolich, Joseph R Fackler, Martin Lee, Anjna Nair, Priyesh Agrawal, Pranita D Tamma, Maria Souli, Scott R Evans, Kerryl E Greenwood-Quaintance, Scott A Cunningham, Robin Patel, Antibacterial Resistance Leadership Group
Author Information
Krupa Parmar: Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota, USA. ORCID
Lauren Komarow: Biostatistics Center, George Washington University , Rockville, Maryland, USA.
Damon W Ellison: Wound Infections Department, Bacterial Diseases Branch, Walter Reed Army Institute of Research , Silver Spring, Maryland, USA.
Andrey A Filippov: Wound Infections Department, Bacterial Diseases Branch, Walter Reed Army Institute of Research , Silver Spring, Maryland, USA. ORCID
Mikeljon P Nikolich: Wound Infections Department, Bacterial Diseases Branch, Walter Reed Army Institute of Research , Silver Spring, Maryland, USA. ORCID
Joseph R Fackler: Adaptive Phage Therapeutics Inc. , Gaithersburg, Maryland, USA.
Martin Lee: Adaptive Phage Therapeutics Inc. , Gaithersburg, Maryland, USA. ORCID
Anjna Nair: Adaptive Phage Therapeutics Inc. , Gaithersburg, Maryland, USA.
Priyesh Agrawal: Adaptive Phage Therapeutics Inc. , Gaithersburg, Maryland, USA.
Pranita D Tamma: Division of Pediatric Infectious Diseases, Department of Pediatrics, Johns Hopkins University School of Medicine , Baltimore, Maryland, USA. ORCID
Maria Souli: Duke Clinical Research Institute , Durham, North Carolina, USA. ORCID
Scott R Evans: Biostatistics Center, George Washington University , Rockville, Maryland, USA.
Kerryl E Greenwood-Quaintance: Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota, USA. ORCID
Scott A Cunningham: Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota, USA. ORCID
Robin Patel: Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota, USA. ORCID
Standardized approaches to phage susceptibility testing (PST) are essential to inform selection of phages for study in patients with bacterial infections. There is no reference standard for assessing bacterial susceptibility to phage. We compared agreement between PST performed at three centers: two centers using a liquid assay standardized between the sites with the third, a plaque assay. Four phages: PaWRA01ø11 (EPa11), PaWRA01ø39 (EPa39), PaWRA02ø83 (EPa83), PaWRA02ø87 (EPa87), and a cocktail of all four phages were tested against 145 . isolates. Comparisons were made within measurements at the two sites performing the liquid assay and between these two sites. Agreement was assessed based on coverage probability (CP), total deviation index, concordance correlation coefficient (CCC), measurement accuracy, and precision. For the liquid assay, there was satisfactory agreement among triplicate measurements made on different days at site 1, and high agreement based on accuracy and precision between duplicate measurements made on the same run at site 2. There was fair accuracy between measurements of the two sites performing the liquid assay, with CCCs below 0.6 for all phages tested. When compared to the plaque assay (performed once at site 3), there was less agreement between results of the liquid and plaque assays than between the two sites performing the liquid assay. Similar findings to the larger group were noted in the subset of 46 . isolates from cystic fibrosis. Results of this study suggest that reproducibility of PST methods needs further development.
