How Temperature-Sensitive Traits Could Explain Why E coli's Lookalike Goes Undetected

In part 2 of our interview, Pelumi (Magret) Oladipo, a fourth-year PhD candidate at Wayne State University School of Medicine, spoke with ContagionLive about phenotypic traits of E marmotae that may help explain its underrecognition as a human pathogen. The discussion, which builds on her diagnostic study presented at ASM Microbe 2025, included new insight into the organism’s temperature-sensitive motility, its frequent misidentification as E coli, and the next steps in validating two species-level diagnostic tools.

“In our study, we have observed that Imamate exhibit a temperature-sensitive motility and biofilm-forming ability, with both the phenotypes more pronounced at lower temperature—to be precise, at 28 degrees Celsius—than that of the body temperature, which is 37 degrees Celsius,” Oladipo said.

Motility is a known virulence factor in many bacterial pathogens. Oladipo explained that their study found E marmotae to be less motile than E coli at both temperatures, which may help explain its lower clinical frequency and potentially different disease presentation.

“This reduced motility may contribute to the reason why imamity infections are less common than E coli, and might also produce a different disease profile when infections occur,” she said.

“Motile bacterials are better able to, you know, migrate to vulnerable sites of infections, more effectively evade tissues, as well as potentially evade various host different responses. Some bacterial pathogens deliberately stop producing flagella at host temperature in order to, you know, avoid detection by the host immune responses, and then motility may not be essential for its pathogenicity.”

This complexity, Oladipo emphasized, underscores the need for more focused research on E marmotae. “Overall, this study is, you know, the study of Imamate is still not well studied, and our findings have already emphasized the complexity of Imamate and its potential to thrive in diverse environments,” she said. To help address the identification challenges, Oladipo’s lab applied their newly developed diagnostic tools to a set of clinical isolates initially labeled as E coli.

“To begin validating tools that we created, you know, we collaborated with a clinical hospital to screen a collection of E coli isolates that was obtained from patient samples,” she said. “Our goal was to, you know, determine whether any had been misidentified and were actually imamati, because, you know, it has often been misdiagnosed as E coli.”

Using a species-specific qPCR assay and a MALDI-TOF MS biomarker, the team re-screened 100 E coli isolates from clinical samples. “We got one out of 100 that was identified as E coli, but it's actually imametic. And this result has been, you know, further confirmed through whole-genome sequencing, supporting the accuracy and the clinical utility of our assay.”

Oladipo believes these tools could soon be applied more broadly in the clinical setting. “Yes, the species-specific qPCR assay and the MALDI-TOF MS biomarker that I have mentioned previously… have a very strong potential for use in clinical microbiology labs or in any clinical laboratory,” she said. “So our assays work very well, and that has been able to, you know, help us to distinguish the species from E coli or other hherical species.”

The findings support the growing recognition of E marmotae as a clinically relevant, yet underdiagnosed, pathogen. With distinct virulence traits and emerging diagnostic solutions, Oladipo’s work adds critical insight into a species long overshadowed by its better-known counterpart, E coli.

Reference

Oladipo PM, Tibbetts RJ, Sivertsen A, et al. New diagnostic methods for Escherichia marmotae and the first report of its identification in clinical isolates in North America. medRxiv. Preprint posted online July 10, 2025. doi:10.1101/2025.07.10.25331261