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Several companies nationwide, with FDA oversight, recalled food products due to potential bacterial contamination, issuing consumer warnings to prevent foodborne illness.

FDA Food Recalls Announced in June 2025 Due to Potential Contamination Risks

A Centers for Disease Control and Prevention (CDC) publication reports on REPEXH01, a strain of Shiga toxin–producing Escherichia coli (STEC) O157:H7, which has been responsible for at least 9 outbreaks in the US since 2017.    

Persistent Strain of E coli That Caused Multiple Outbreaks Identified

A multistate outbreak of E coli O157:H7 infections has been served at catering events, restaurants, and schools.

E coli Outbreak Linked to Iceberg and Romaine Lettuce Blend

It is not only about cooking the food to the correct temperature, but also how long the food should sit out, and safe storage after the meal is over. Here is more information to have a healthy holiday.

Thanksgiving Food Safety Tips

Wolverine Packing Co is recalling ground beef due to potential contamination with E coli O157:H7

15 E Coli Cases Lead to Recall of 167,000 Pounds of Ground Beef

At ASM Microbe 2025, Pelumi Oladipo discusses E marmotae’s reduced motility, misidentification as E coli, and the diagnostic tools closing the gap

In part 2 of our interview, Pelumi (Magret) Oladipo, a fourth-year PhD candidate at Wayne State University School of Medicine, spoke with 

 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 

, and the next steps in validating two species-level diagnostic tools.

 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 

 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 

, 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 

. “Overall, this study is, you know, the study of 

 is still not well studied, and our findings have already emphasized the complexity of 

 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 

“To begin validating tools that we created, you know, we collaborated with a clinical hospital to screen a collection of 

 isolates that was obtained from patient samples,” she said. “Our goal was to, you know, determine whether any had been misidentified and were actually 

, because, you know, it has often been misdiagnosed as 

Using a species-specific qPCR assay and a MALDI-TOF MS biomarker, the team re-screened 100 

 isolates from clinical samples. “We got one out of 100 that was identified as 

. 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 

The findings support the growing recognition of 

 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, 

Oladipo PM, Tibbetts RJ, Sivertsen A, et al. New diagnostic methods for 

 and the first report of its identification in clinical isolates in North America. 

. Preprint posted online July 10, 2025. doi:10.1101/2025.07.10.25331261

At ASM Microbe 2025, Pelumi Oladipo discusses E marmotae’s reduced motility, misidentification as E coli, and the diagnostic tools closing the gap.

Conferences

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

Presented at ASM Microbe, Pelumi Oladipo's study identifies the first North American human case of E marmotae infection and introduces methods to improve species-level diagnosis.     Ask ChatGPT

New Diagnostic Tools Differentiate Escherichia marmotae from E coli in Clinical Settings

At the 2025 American Society for Microbiology Microbe conference, Pelumi (Magret) Oladipo, a fourth-year PhD candidate in immunology and microbiology at Wayne State University School of Medicine, presented a study describing 2 new diagnostic methods that distinguish 

. The study also documents the first confirmed case of human infection with 

 has been classified as a “cryptic clade” of 

, whole-genome sequencing reveals it diverges by approximately 10%. This divergence has clinical implications, yet current diagnostic systems frequently misidentify 

, including matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) platforms used in clinical laboratories.

 is also known as HRA, clade V, and it is one of the 

 cryptic clades that has already diverged from 

,” Oladipo said in an interview. “It's the one that diverged the furthest, and it is about 10% different from 

 was primarily detected in environmental reservoirs, including dogs, bats, and raccoons. Recently, it has been isolated from human infections, including septicemia, urinary tract infections, pyelonephritis, and sepsis.

 based on standard diagnostic tests—biochemical assays as well as colony morphology, coliform profiles—only by nucleotide differences,” Oladipo explained. “So due to this phenotypic similarity to 

, it is possible that this species must have been overlooked in the past, misidentified as 

, thereby underestimating its clinical significance as a potential pathogen.”

To address this diagnostic gap, Oladipo’s team developed a TaqMan polymerase chain reaction (PCR) assay targeting the 

 used as a positive control. The assay showed 100% specificity for 

The team also developed a mass spectrometry–based biomarker to improve detection using MALDI-TOF-MS. Using the bioMérieux VITEK system, the study results found that 

 with a median in vitro diagnostic (IVD) confidence score of 99.9%. Although research use only scores for 

 were significantly lower (median, 0%) than those for 

 < .0001), the systems failed to differentiate between the species in clinical practice. A spectral peak between a mass to charge ratio of 7260 to 7268 consistently identified 

 presented peaks from 7268 to 7280, with no overlap (

Application of both methods to 176 clinical isolates identified the first confirmed case of 

 in a human infection in North America. The isolate had initially been identified as 

 based on a 99.1% IVD confidence score but was later confirmed as 

 through PCR and whole-genome sequencing. This isolate contained multiple antibiotic resistance gene markers and lacked motility at 37 °C, which is not typically observed in clinical 

“This misidentification means that we don't know how it causes disease, how virulent it is compared with 

, or whether different treatments might work better for infections caused by 

“So we have the MALDI-TOF mass spectrometry, which is mostly used in clinical laboratories. They use that in identifying bacteria, and that also isn't reliable to distinguish this species,” she added. “So the first 

 spectrum in the Bruker database was included in 2021, but that also couldn't even distinguish 

. And there are other systems—like the bioMérieux MALDI-TOF mass spectrometry—that still lack 

“So as a result, many clinical laboratories lack the necessary tools or protocols to identify this species accurately, and this misdiagnosis has critical implications, including inaccurate infection tracking, suboptimal antibiotic treatment decisions, and an incomplete understanding of the prevalence and the pathogenic potential of 

, which is still currently understudied,” she said.

Oladipo concluded, “So that’s why our laboratory has been able to develop 2 high-identification methods. No. 1 method is the TaqMan PCR assay using species-specific primers. And the other method is the MALDI-TOF mass spectrometry–based biomarker, where we were able to identify a unique spectral peak that reliably distinguishes 

Presented at ASM Microbe, Pelumi Oladipo's study identifies the first North American human case of E marmotae infection and introduces methods to improve species-level diagnosis.

New Diagnostic Methods Differentiate Escherichia marmotae From Escherichia coli in Clinical Isolates

Mark Riddle, MD, DrPH, associate dean of clinical research, University of Nevada, Reno, associate chief of staff for research, VA Sierra Nevada Health System, speaks to Contagion at ACG 2019 about the results of a study looking into microbiome changes associated with single-dose antibiotics for the treatment of traveler's diarrhea.

Interview transcript (modified slightly for readability):

 We looked at subjects' stool functional microbiome before they got their treatment [single-dose antibiotics]. We looked at it seven days after. And then we looked at it at 21 days. 

We didn't see a lot of change in the functional microbiome of those that were treated. There were some acute changes, but then they reverted around day 21. We also looked for measures of antibiotic resistance. We looked at a resistome, a compilation of all resistance genes that you can find in the stool, as well as some targeted genes that were specific to ESBL-producing Enterobacteriaceae. We didn't see any real increase of those as well. 

Our main conclusions were that the study was small, but that we don't see major disturbances and major resistance acquisition with single-dose antibiotics. We didn't have a comparison group of a three day multi-dose regimen, and we didn't have a placebo group. Interpretations of our results have to be with caution.

But the amount of ESBL that we detected in this trial was much less than that's which has been seen in these observational studies. If you go to Africa, on average, 35% of travelers returning will have ESBL-producing E coli acquisition, we saw around 9%. Because we didn't see a lot of resistance acquisition, we couldn't really detect differences in the microbiome that would explain that.

Mark Riddle, MD, DrPH, speaks to Contagion at ACG 2019 about the results of a study looking into microbiome changes associated with single-dose antibiotics for the treatment of traveler's diarrhea.

Observing Microbiome Changes After Single-Dose Antibiotics for Traveler's Diarrhea

 Elizabeth Hirsch, PharmD, assistant professor at the University of Minnesota College of Pharmacy, and Elizabeth Smith, PharmD candidate at the University of Minnesota College of Pharmacy, discuss fosfomycin susceptibility testing.

There has been a lot of discussion recently at CLSI, the Clinical and Laboratory Standards Institute, about the appropriateness of the current susceptibility breakpoints for fosfomycin, and the fact that glucose 6-phosphate is used during in vitro susceptibility testing. However, most likely glucose 6-phosphate is not actually found in the urine. So there are some concerns whether our in vitro testing actually reflects what is happening in vivo in a patient. Currently, there are no susceptibility breakpoints from CLSI specific to 

 for fosfomycin. In the clinic what is happening is if this drug is tested, the 

 breakpoints points are being extrapolated to other organisms that we don't have breakpoints for. So we thought it was important to look at activity of fosfomycin against 

 and extrapolate those breakpoints to see exactly how active the drug looks, according to the 

The main takeaways from our research were...we were comparing the 4 different susceptibility testing methods: the reference method, which Betsy stated, was the agar dilution, and then we also looked at disk diffusion, Etest and then broth microdilution. The clinical isolates that that we used were slightly skewed to be more resistant—about 50% of our isolates were multidrug-resistant and about 20% were pan-resistant isolates. When we compared the susceptibilities across all 4 methods, they were about 50% susceptible, but the MICs varied widely across all 4 methods ranging from less than 2 all the way up to greater than 1024. Betsy mentioned that current recommendations per CLSI are to ignore the inner colonies that potentially can be frequently seen in disk diffusion and Etest. And so we kind of wanted to look and see how those MICs compared to the parent strains. And so we actually subcultured those out and then ran the same MIC tests using broth microdilution and compared the parent MICs to the daughter MICs and found in each case that the daughter strains were a lot higher in terms of MICs when compared to the parents strains.

Future research avenues for this project are to continue building on the isolate set that we've been testing. We have isolates from the US and we also have some Australian collaborators. So we're now adding into our isolate set so that we have an international set of isolates to continue looking at activity of fosfomycin against 

. And then, as Elizabeth mentioned, we are looking at the frequency of inner colonies that are seen there. And so for the isolates that we have subcultured, the daughter mutant isolates, we are now going to look at those with whole genome sequencing and assess the resistance mechanisms of both the parents strains and the daughter isolates, so kind of to try to understand what are the resistance mechanisms, leading to either non-susceptibility or resistance for 

Elizabeth Hirsch, PharmD, and Elizabeth Smith, PharmD candidate, discuss fosfomycin susceptibility testing.

Lack of Agreement Between Fosfomycin Susceptibility Testing Methods Against Pseudomonas

 Elizabeth Hirsch, PharmD, assistant professor at the University of Minnesota College of Pharmacy, and Mélanie Mahoney, PharmD candidate at the University of Minnesota College of Pharmacy, discuss their poster on 

: What sparked your interest in this topic?

, specifically UTIs, so we're interested in ST131 because it's found to be associated with a lot of resistance, specifically fluoroquinolone resistance, so that's why we were specifically interested in this sequence type of 

: What were the main findings of your study?

: We used 2 isolate sets, 1 collected from patients in Boston, Massachusetts, and 1 collected from patients in Minneapolis, Minnesota, and these 2 isolate sets were collected from roughly the same time period in 2013 and 2014 and so we were collaborating with Jim Johnson, who's an ST131 expert. When we compared the 2 isolate sets...

: We found that overall their phylogenetic distribution was pretty similar. We looked at their resistance genes profiles [and] they were pretty similar. One key finding was that the CTX-M27 was found uniquely in the Boston isolates, so none in the Minneapolis set. Also the ESBL prevalence was slightly greater in the Boston isolate set than the Minneapolis set so that's been a new finding. The CTX-M27 has been found in Japan, in Europe, but we've found it now in United States clinical isolates.

: To what do you attribute the differences in findings between the 2 cities?

: We're not sure entirely what accounts for the difference between the 2 cities, but we hypothesize that, with Boston being on the coast, there may be more international patients who are seen at the hospital where the isolates were collected as opposed to patients seen in Minneapolis maybe from more rural settings in the midwest of the United States. However, we're not exactly sure what accounts for the difference.

: Those isolates were also from 2013 and 2014. It's possible that now there might be some of that CTX-M27 in Minneapolis, as well.

: Now we're interested in some of the clinical outcomes associated with this ST131, specifically the H30, possibly the C1-M27 clade infections as well. We'd like to do some studies to see if the ST131-H30 is associated with worse clinical outcomes if it's also associated with increased resistance.

We're also interested in doing a comparison of a more contemporaneous isolate set so collecting more isolates from Minneapolis to see if there have been changes from what we saw in the 2013 isolate set so that's something else that we plan to collect more isolates and see if those have changed over time.

Escherichia coli ST131 in Boston versus Minneapolis: prevalence, virulence genes, and antibiotic resistance

," was presented Monday, April 15, at ECCMID 2019.

Elizabeth Hirsch, PharmD, and Mélanie Mahoney, PharmD candidate, discuss their poster on Escherichia coli ST131 in Boston vs Minneapolis at ECCMID 2019.

Escherichia coli ST131: Prevalence, Resistance, and Virulence in Boston vs Minneapolis

James S. Lewis, PharmD, FIDSA, Co-Director of Antibiotic Stewardship, Oregon Health and Science University, addresses the issues that surround current antibiotic development. The primary issue involves a common perception shared by some pharmaceutical companies regarding return on investment.

James S. Lewis, PharmD, FIDSA, addresses the issues that surround current antibiotic development.

Addressing Issues Surrounding Current Antibiotic Development

The MCR1_NJ gene has been found to be both colistin- and carbapenem-resistant. Barry Kreiswirth, PhD, founding director, Public Health Research Institute Tuberculosis Center, professor of medicine at Rutgers University, discusses his team’s findings on MCR1_NJ and bacterial drug resistance. In addition to the discovery of the gene MCR1_NJ, other researchers have identified another colistin-resistance gene dubbed 

. Dr. Kreiswirth notes that with the addition of carbapenem resistance, MCR1_NJ gives bacteria the ability to be resistant to two last-line treatments. This emphasizes the need for surveillance for MCR1_NJ and other known resistance genes.

 Interview Transcript (slightly modified for readability)

 gene that we found in our strain has also been found in other strains throughout the United States, mostly associated with animal reservoirs. We know that pig isolates of 

 as well as isolates coming from bovine, have the 

 gene. The surprise wasn’t that we found it in a human, the surprise was that we found it in association with a second resistance gene, which was the carbapenem-resistant [gene]; that’s the new finding.

Barry Kreiswirth, PhD, founding director, Public Health Research Institute Tuberculosis Center, professor of medicine at Rutgers University, discusses the implications of the findings of his study.
 

E. Coli

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