ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Infectious Agents and Disease
Volume 16 - 2025 | doi: 10.3389/fmicb.2025.1664775
This article is part of the Research TopicRapid and Efficient Analytical Technologies for Pathogen DetectionView all 11 articles
New Diagnostic Methods for Escherichia marmotae and the First Report of its Identification in Clinical Isolates in North America
Provisionally accepted
Pelumi Oladipo1*
Robert J Tibbetts2
Audun Sivertsen3Justin M Barger2Torbjørn S Bruvold3Alemu Fite4Matthew Sims5Marcus Zervos2Ali Jomaa6
Jeffrey Ram7- 1Department of Biochemistry, Microbiology & Immunology, School of Medicine, Wayne State University, Detroit, United States
- 2Henry Ford Health System, Detroit, United States
- 3Haukeland Universitetssjukehus, Bergen, Norway
- 4Corewell Health, Royal Oak, United States
- 5Corewell Health William Beaumont University Hospital, Royal Oak, United States
- 6Wayne State University, Detroit, United States
- 7Wayne State University School of Medicine, Detroit, United States
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Genomic sequences of E. marmotae and E. coli differ by 10%. Discovered as an environmental "cryptic clade" of Escherichia, E. marmotae also occurs in human infections. Microbiological and MALDI-TOF-MS methods frequently misidentify E. marmotae as E. coli. Our goal was to develop methods that reliably distinguish E. marmotae from E. coli to improve therapeutic decisions and treatments.A Taqman PCR method was developed to distinguish E. marmotae from E. coli based on sequences of uidA and uidB and a positive control targeting adk. UidA-and uidB species-specific PCR amplified DNA from E. marmotae with 100% specificity, and not from E. coli or other Escherichia species.The Biomérieux VITEK MALDI-TOF-MS consistently misidentified E. marmotae as E. coli, with median IVD confidence scores for both E. marmotae and E. coli of 99.9%; however, RUO scores for E. marmotae (median 0%) were significantly lower (P<0.0001) than for E. coli (median=87.4%). The spectral peak between m/z 7250 to 7280 consistently occurred between 7260 and 7268 in E. marmotae and only between 7268 and 7280 in E. coli, with no overlap (p<0.001).Application of these spectral criteria to 176 clinical isolates revealed the first isolate of E. marmotae from a human infection in North America. The isolate had originally been diagnosed as E. coli based on a 99.1% IVD confidence score. This first North American clinical isolate was confirmed as E. marmotae by Taqman-PCR and whole genome sequencing. This isolate had numerous antibiotic resistance gene markers and unlike most clinical E. coli, this E. marmotae isolate lacked motility at 37 ºC.Clinical tests based on these methods of differentiating E. marmotae and E. coli may assist in therapeutic decisions. Moreover, discovering the identity of the structure underlying the shift in the MALDI-TOF-MS peak may help determine if it has a special role in infection.we identify a specific peak in the MALDI-TOF-MS spectra that is exclusively and reliably associated with E. marmotae that enabled the discovery of the first E. marmotae strain isolated in North America.
Keywords: qPCR, Escherichia marmotae, MALDI -TOF MS, bioMérieux, spectral peaks, Bacterial identification, Species-specific qPCR, Vitek MS
Received: 12 Jul 2025; Accepted: 18 Aug 2025.
Copyright: © 2025 Oladipo, Tibbetts, Sivertsen, Barger, Bruvold, Fite, Sims, Zervos, Jomaa and Ram. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Pelumi Oladipo, Department of Biochemistry, Microbiology & Immunology, School of Medicine, Wayne State University, Detroit, United States
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