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How Harmless E. Coli Turns Dangerous

Hannover Medical School researcher Prof. Galardini from the RESIST Cluster of Excellence has found causes for bloodstream infections in the genes of bacteria. This will enable better diagnostics and vaccinations in the future.

Escherichia coli bacteria live in the intestines of humans and play an important role there for normal intestinal function as well as for a functioning immune system. These intestinal inhabitants do not form a uniform population, but consist of a large number of strains that differ greatly in their genome and also in their metabolism.

Most strains of E. Coli are harmless, but some can cause diarrhea or urinary tract infections and—if they enter the blood—bloodstream infections and sepsis via their toxins. Sepsis is the third most common cause of death in Germany.

The bacteria have caused increasingly more diseases

Prof. Dr. Marco Galardini's team has found that E. Coli has a significant genetic variation that contributes to the transition between the harmless life in the intestine (commensalism) and the pathogenic form. In addition, the researchers were also able to show that this bacterial species has evolved more toward causing disease over the years.

"Building on these findings, we envision the creation of better molecular diagnostic tools in the future, and these results might also be important for vaccines development," says Prof. Galardini.

The team published their findings in the journal PLoS Genetics. First authors are Judit Burgaya and Julie Marin. The work originated in TWINCORE in collaboration with Prof. Erick Denamur (INSERM, Paris) and Prof. François Blanquart (Collège de France).

Significant genetic differences between harmless and dangerous bacteria

The team examined a collection of about 900 E. Coli isolates that caused blood infections and 370 harmless isolates. The samples were collected over a 17-year period (from 2000 to 2017) by the team of Prof. Erick Denamur.

"We found significant differences between the disease-causing and the harmless isolates—both in their pangenomes, i.E. The totality of genes of the respective isolates, and in their genetic backgrounds, in terms of the presence of virulence-associated genes and antimicrobial resistance genes," says Prof. Galardini.

Using another commensal collection from 1980, the group also found that pathogenicity might have increased steadily from 1980 through 2000 to 2010.

This work is the third in a series of studies aimed at understanding the genetic determinants of the ability of E. Coli to cause bloodstream infections. The team published the first two papers in 2020 and 2022.

More information: Judit Burgaya et al, The bacterial genetic determinants of Escherichia coli capacity to cause bloodstream infections in humans, PLOS Genetics (2023). DOI: 10.1371/journal.Pgen.1010842

Provided by Medizinische Hochschule Hannover

Citation: How harmless E. Coli turns dangerous (2023, August 18) retrieved 29 August 2023 from https://phys.Org/news/2023-08-harmless-coli-dangerous.Html

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Four Students Hospitalized In E. Coli Outbreak At The University Of Arkansas

Health officials are investigating an outbreak of E. Coli food poisoning among students at the University of Arkansas, with dozens reporting symptoms and at least four needing treatment in the hospital.

Among those affected are two 19-year-olds sorority members who developed a serious complication that can lead to kidney failure after being infected with the E. Coli strain O157:H7. That's according to Bill Marler, a Seattle food safety lawyer who said he reviewed the patients' medical records after being contacted by the families.

One student was still in the intensive care unit of a local hospital Tuesday, Marler said, while the other returned home to recover.

About 100 students reported symptoms of E. Coli infection, officials with the Arkansas Department of Health said, though it's not clear how many are part of the outbreak. Officials are analyzing responses from a survey of more than 3,200 people to try to identify the source of the illnesses.

The outbreak, which likely began before Aug. 18, does not appear connected to the university's public dining facilities, health officials said in a statement Monday. Classes at the University of Arkansas started Aug. 21.

E. Coli bacteria live in the guts of humans and animals. Some strains, including E. Coli O157:H7, produce dangerous toxins that can lead to serious illness and even death in humans. Common sources of E. Coli outbreaks include ground beef and leafy greens.

Symptoms of E. Coli food poisoning include a fever higher than 102 degrees Fahrenheit, diarrhea for more than three days, severe vomiting, dehydration and dizziness.

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute's Science and Educational Media Group. The AP is solely responsible for all content.

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Impact Of Invasive E Coli Infections In Older Adults Spotlighted

CDC

An analysis of invasive extraintestinal pathogenic Escherichia coli disease (IED) in older patients found a substantial clinical burden, with considerable long-term consequences, researchers reported yesterday in BMC Infectious Diseases.

To describe and characterize the short- and long-term impacts of IED, which comprises sepsis, bacteremia, peritonitis, meningitis, and other infectious syndromes, researchers from Europe, Canada, and the United States analyzed data on patients aged 60 and older with either a positive E coli culture and one or more signs of sepsis or a positive E coli culture in urine with urinary tract infection and signs of sepsis. The primary outcomes analyzed were clinical outcomes, medical resource use, and E coli isolate characteristics.

A third of patients admitted to ICU

Overall, 19,773 patients with IED from October 2015 through March 2020 were included (mean age, 76.8 years; 67.4% female; 78.5% with signs of sepsis). The vast majority of encounters involved community-onset IED (94.3%) and required hospitalization (96.5%; mean duration, 6.9 days), with 32.4% of patients being admitted to the intensive care unit (mean duration, 3.7 days) and 8.6% requiring mechanical ventilation. Nearly all patients (99.3%) were treated with antibiotics and typically received several antibiotic courses.

Nearly two thirds (61.7%) of E coli isolates were resistant to one or more antibiotic category, and 34.4% were resistant to three or more antibiotic categories. Following their first IED encounter, 34.8% of patients were transferred to a skilled nursing/intermediate care facility, and 6.8% had died. During the 12-month observation period, 36.8% of IED patients were re-hospitalized, 2.4% had IED recurrence, and in-hospital death increased to 10.9%.

This burden is particularly high in the presence of antibiotic resistance.

The study authors say the findings are important given the global increase in E coli infections and rising rates of antibiotic resistance.

"The findings suggest that IED is associated with an acute burden during the initial hospital encounter and may lead to poor outcomes even after the encounter is resolved," the study authors wrote. "This burden is particularly high in the presence of antibiotic resistance, which is an important consideration for an increasing aging population."

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