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Smith RD, Zhan M, Zhang S, Leekha S, Harris A, Doi Y, Evans S, Kristie Johnson J, Ernst RK. Comparison of three rapid diagnostic tests for bloodstream infections using Benefit-risk Evaluation Framework (BED-FRAME). J Clin Microbiol 2024; 62:e0109623. [PMID: 38054730 PMCID: PMC10793330 DOI: 10.1128/jcm.01096-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 10/20/2023] [Indexed: 12/07/2023] Open
Abstract
Rapid diagnostic tests (RDTs) for bloodstream infections have the potential to reduce time to appropriate antimicrobial therapy and improve patient outcomes. Previously, an in-house, lipid-based, matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) method, Fast Lipid Analysis Technique (FLAT MS), has shown promise as a rapid pathogen identification method. In this study, FLAT MS for direct from blood culture identification was evaluated and compared to FDA-cleared identification methods using the Benefit-risk Evaluation Framework (BED-FRAME) analysis. FLAT MS was evaluated and compared to Bruker Sepsityper and bioMérieux BioFire FilmArray BCID2 using results from a previous study. For this study, 301 positive blood cultures were collected from the University of Maryland Medical Center. The RDTs were compared by their sensitivities, time-to-results, hands-on time, and BED-FRAME analysis. The overall sensitivity of all platforms compared to culture results from monomicrobial-positive blood cultures was 88.3%. However, the three RDTs differed in their accuracy for identifying Gram-positive bacteria, Gram-negative bacteria, and yeast. Time-to-results for FLAT MS, Sepsityper, and BioFire BCID2 were all approximately one hour. Hands-on times for FLAT MS, Sepsityper, and BioFire BCID2 were 10 (±1.3), 40 (±2.8), and 5 (±0.25) minutes, respectively. BED-FRAME demonstrated that each RDT had utility at different pathogen prevalence and relative importance. BED-FRAME is a useful tool that can used to determine which RDT is best for a healthcare center.
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Affiliation(s)
- Richard D. Smith
- Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland, USA
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, Maryland, USA
| | - Min Zhan
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Shanshan Zhang
- Biostatistics Center and the Department of Biostatistics and Bioinformatics, The George Washington University, Washington, D.C., USA
| | - Surbhi Leekha
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Anthony Harris
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Yohei Doi
- Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Scott Evans
- Biostatistics Center and the Department of Biostatistics and Bioinformatics, The George Washington University, Washington, D.C., USA
| | - J. Kristie Johnson
- Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, Maryland, USA
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Lakshmanan D, Ramasamy D, Subramanyam V, Saravanan SK. Mobile colistin resistance (mcr) genes and recent developments in colistin resistance detection. Lett Appl Microbiol 2023; 76:ovad102. [PMID: 37673673 DOI: 10.1093/lambio/ovad102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/17/2023] [Accepted: 09/05/2023] [Indexed: 09/08/2023]
Abstract
The peptide antibiotic colistin has been reserved as a last resort antibiotic treatment option for cases where other antibiotics including carbapenems have failed. Recent emergence of colistin resistance and discovery of mobile colistin resistance (mcr) genes, which encode the cell wall modifying phosphoethanolamine transferase enzyme, complicates the issue. The mcr genes have been associated with conjugative plasmids and can be horizontally transferred between different bacterial species. The global spread of mcr genes has been extensively documented and this warrants surveillance of the resistance genes in the community. However, susceptibility testing of colistin is fraught with practical challenges owing to the chemical nature of the drug and multiple mechanisms of resistance. Although broth microdilution is the current gold standard for colistin susceptibility testing, the method poses technical challenges. Hence, alternative detection methods for screening colistin resistance are the need of the hour. Several methods have been studied in the recent times to address this issue. In this review, we discuss some of the recent developments in the detection of colistin resistance.
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Affiliation(s)
- Divya Lakshmanan
- Mahatma Gandhi Medical Advanced Research Institute (MGMARI), Sri Balaji Vidyapeeth (Deemed-to-be-University), Pillayarkuppam, Pondicherry 607042, India
| | - Dhamodharan Ramasamy
- Mahatma Gandhi Medical Advanced Research Institute (MGMARI), Sri Balaji Vidyapeeth (Deemed-to-be-University), Pillayarkuppam, Pondicherry 607042, India
| | - Veni Subramanyam
- Mahatma Gandhi Medical Advanced Research Institute (MGMARI), Sri Balaji Vidyapeeth (Deemed-to-be-University), Pillayarkuppam, Pondicherry 607042, India
| | - Suresh Kumar Saravanan
- Mahatma Gandhi Medical Preclinical Research Centre (MGMPRC), Sri Balaji Vidyapeeth (Deemed-to-be-University), Pillayarkuppam, Pondicherry 607402, India
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Pětrošová H, Mikhael A, Culos S, Giraud-Gatineau A, Gomez AM, Sherman ME, Ernst RK, Cameron CE, Picardeau M, Goodlett DR. Lipid A structural diversity among members of the genus Leptospira. Front Microbiol 2023; 14:1181034. [PMID: 37303810 PMCID: PMC10248169 DOI: 10.3389/fmicb.2023.1181034] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 05/02/2023] [Indexed: 06/13/2023] Open
Abstract
Lipid A is the hydrophobic component of bacterial lipopolysaccharide and an activator of the host immune system. Bacteria modify their lipid A structure to adapt to the surrounding environment and, in some cases, to evade recognition by host immune cells. In this study, lipid A structural diversity within the Leptospira genus was explored. The individual Leptospira species have dramatically different pathogenic potential that ranges from non-infectious to life-threatening disease (leptospirosis). Ten distinct lipid A profiles, denoted L1-L10, were discovered across 31 Leptospira reference species, laying a foundation for lipid A-based molecular typing. Tandem MS analysis revealed structural features of Leptospira membrane lipids that might alter recognition of its lipid A by the host innate immune receptors. Results of this study will aid development of strategies to improve diagnosis and surveillance of leptospirosis, as well as guide functional studies on Leptospira lipid A activity.
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Affiliation(s)
- Helena Pětrošová
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
- University of Victoria Genome British Columbia Proteomics Center, University of Victoria, Victoria, BC, Canada
| | - Abanoub Mikhael
- University of Victoria Genome British Columbia Proteomics Center, University of Victoria, Victoria, BC, Canada
| | - Sophie Culos
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | | | - Alloysius M. Gomez
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - Matthew E. Sherman
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, MD, United States
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, MD, United States
| | - Caroline E. Cameron
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, WA, United States
| | - Mathieu Picardeau
- Institut Pasteur, Université Paris Cité, CNRS UMR 6047, Biology of Spirochetes Unit, Paris, France
| | - David R. Goodlett
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
- University of Victoria Genome British Columbia Proteomics Center, University of Victoria, Victoria, BC, Canada
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Yang H, Smith RD, Sumner KP, Goodlett DR, Johnson JK, Ernst RK. A Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Direct-from-Urine-Specimen Diagnostic for Gram-Negative Pathogens. Microbiol Spectr 2022; 10:e0373022. [PMID: 36255333 PMCID: PMC9769899 DOI: 10.1128/spectrum.03730-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 09/28/2022] [Indexed: 01/10/2023] Open
Abstract
Urinary tract infections (UTIs) pose a major public health burden. The vast majority of UTIs are caused by Gram-negative bacteria. Current culture-based pathogen identification methods may require up to 24 to 48 h of incubation. In this study, we developed and evaluated a method for Gram-negative pathogen identification direct from urine, without culture, via matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) in approximately 1 h. Urine samples were collected (n = 137) from the University of Maryland Medical Center clinical microbiology laboratory. To identify bacteria direct from urine, two methods were evaluated. First, 1 μL of urine was directly spotted onto the MALDI target plate, and second, 1 mL of urine was centrifuged at 8,000 rpm for 5 min before processing using the fast lipid analysis technique (FLAT). Mass spectra were acquired on the Bruker MALDI Biotyper sirius system in the negative-ion mode. Results were compared to those of standard culture methods. When 1 μL of urine was directly spotted, positive agreement was 81.5% (101/124) and, after centrifugation, 94.4% (117/124) relative to that of standard culture methods. Negative agreement for both methods was 100% (13/13). The time to results for both of the specimen preparation methods using the FLAT extraction protocol was approximately 1 h, with minimal hands-on time required (<5 min). The ability to rapidly identify pathogens directly from urine, without the need for culture, allows for faster turnaround times and, potentially, improved patient outcomes. Overall, the FLAT extraction protocol, in combination with lipid A identification, provides a reproducible and accurate method to rapidly identify urinary pathogens. IMPORTANCE This study describes and evaluates a direct-from-urine extraction method that allows identification of Gram-negative bacteria via MALDI-TOF MS within 1 h. Currently, identification of urinary pathogens requires 24 h of culture prior to identification. While this method may not replace culture, we demonstrate its utility in screening for common urinary pathogens. By providing identifications in under 1 h, clinicians can potentially treat patients sooner with more-targeted antimicrobial therapy. In turn, earlier treatment can improve patient outcome and antimicrobial stewardship. Furthermore, MADLI-TOF MS is a readily available, easy-to-use diagnostic tool in clinical laboratories, making implementation of this method possible.
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Affiliation(s)
- Hyojik Yang
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, USA
| | - Richard D. Smith
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, USA
- Department of Pathology, School of Medicine, University of Maryland, Baltimore, Maryland, USA
| | - Kylie P. Sumner
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, USA
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - David R. Goodlett
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
- International Centre for Cancer Vaccine Science, University of Gdansk, Gdansk, Poland
| | - J. Kristie Johnson
- Department of Pathology, School of Medicine, University of Maryland, Baltimore, Maryland, USA
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, USA
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Sherman ME, Smith RD, Gardner FM, Goodlett DR, Ernst RK. A Sensitive GC-MS Method for Quantitation of Lipid A Backbone Components and Terminal Phosphate Modifications. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:2301-2309. [PMID: 36326685 PMCID: PMC9933694 DOI: 10.1021/jasms.2c00266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Lipid A, the hydrophobic anchor of lipopolysaccharide (LPS) present in the outer membrane of Gram-negative bacteria, serves as a target for cationic antimicrobial peptides, such as polymyxins. Membrane stress from polymyxins results in activation of two-component regulatory systems that produce lipid A modifying enzymes. These enzymes add neutral moieties, such as aminoarabinose (AraN) and ethanolamine (EtN) to lipid A terminal phosphates that mask the phosphate's negative charge and inhibit electrostatic interaction with the cationic polymyxins. Currently, these modifications may be detected by MALDI-TOF MS; however, this analysis is only semiquantitative. Herein we describe a GC-MS method to quantitate lipid A backbone components, glucosamine (GlcN) and inorganic phosphate (Pi), along with terminal phosphate modifications AraN and EtN. In this assay, lipid A is isolated from Gram-negative bacterial samples, hydrolyzed into its individual moieties, and derivatized via methoximation followed by silylation prior to analysis via GC-MS. Changes in AraN and EtN quantity were characterized using a variety of regulatory mutants of Salmonella, revealing differences that were not detected using MALDI-TOF MS analysis. Additionally, an increase in the abundance of AraN and EtN modifications were observed when resistant Enterobacter and Escherichia coli strains were grown in the presence of colistin (polymyxin E). Lastly, increased levels of Pi were found in bisphosphorylated lipid A compared to monophosphorylated lipid A samples. Because lipid A modifications serve as indicators of polymyxin resistance in Gram-negative bacteria, this method provides the capacity to monitor polymyxin resistance by quantification of lipid A modification using GC-MS.
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Affiliation(s)
- Matthew E Sherman
- Department of Microbial Pathogenesis, University of Maryland─Baltimore, Baltimore, Maryland 21201, United States
| | - Richard D Smith
- Department of Microbial Pathogenesis, University of Maryland─Baltimore, Baltimore, Maryland 21201, United States
| | - Francesca M Gardner
- Department of Microbial Pathogenesis, University of Maryland─Baltimore, Baltimore, Maryland 21201, United States
| | - David R Goodlett
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada
- University of Gdansk, International Centre for Cancer Vaccine Science, Gdansk, 80-210, Poland
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland─Baltimore, Baltimore, Maryland 21201, United States
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Yang H, Smith RD, Chandler CE, Johnson JK, Jackson SN, Woods AS, Scott AJ, Goodlett DR, Ernst RK. Lipid A Structural Determination from a Single Colony. Anal Chem 2022; 94:7460-7465. [PMID: 35576511 PMCID: PMC9392460 DOI: 10.1021/acs.analchem.1c05394] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We describe an innovative use for the recently reported fast lipid analysis technique (FLAT) that allows for the generation of MALDI tandem mass spectrometry data suitable for lipid A structure analysis directly from a single Gram-negative bacterial colony. We refer to this tandem MS version of FLAT as FLATn. Neither technique requires sophisticated sample preparation beyond the selection of a single bacterial colony, which significantly reduces overall analysis time (∼1 h), as compared to conventional methods. Moreover, the tandem mass spectra generated by FLATn provides comprehensive information on fragments of lipid A, for example, ester bonded acyl chain dissociations, cross-ring cleavages, and glycosidic bond dissociations, all of which allow the facile determination of novel lipid A structures or confirmation of expected structures. In addition to generating tandem mass spectra directly from single colonies, we also show that FLATn can be used to analyze lipid A structures taken directly from a complex biological clinical sample without the need for ex vivo growth. From a urine sample from a patient with an E. coli infection, FLATn identified the organism and demonstrated that this clinical isolate carried the mobile colistin resistance-1 gene (mcr-1) that results in the addition of a phosphoethanolamine moiety and subsequently resistance to the antimicrobial, colistin (polymyxin E). Moreover, FLATn allowed for the determination of the existence of a structural isomer in E. coli lipid A that had either a 1- or 4'-phosphate group modification by phosphoethanolamine generated by a change of bacterial culture conditions.
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Affiliation(s)
- Hyojik Yang
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD 21201 USA
| | - Richard D. Smith
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD 21201 USA
- Department of Pathology, School of Medicine, University of Maryland, Baltimore, MD 21201 USA
| | - Courtney E. Chandler
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD 21201 USA
| | - J. Kristie Johnson
- Department of Pathology, School of Medicine, University of Maryland, Baltimore, MD 21201 USA
| | - Shelley N. Jackson
- Translational Analytical Core, NIDA IRP, NIH, Biomedical Research Center, 251 Bayview Boulevard, Suite 200, Room 01B216, Baltimore, MD 21224, USA
| | - Amina S. Woods
- Structural Biology Core, NIDA IRP, NIH, 333 Cassell Drive, Room 1120, Baltimore, MD 21224, USA
- Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine. Baltimore, MD 21205 USA
| | - Alison J. Scott
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD 21201 USA
- Maastricht MultiModal Molecular Imaging (M4I) Institute, Maastricht University, Maastricht 6229 ER, Netherlands
| | - David R. Goodlett
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Road. Victoria, BC V8P 5C2, Canada
- International Centre for Cancer Vaccine Science, University of Gdańsk, ul. Kładki 24 80-822 Gdańsk, Poland
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD 21201 USA
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