Low-temperature electron micrograph of a cluster of E. coli bacteria, magnified 10,000 times. Each individual bacterium is oblong shaped. Credit: ARS
Key point:
- A new study shows the genetic differences between harmless and pathogenic E.coli.
- The researchers noted that E.coli has increasingly evolved toward the pathogenic form in recent years.
- Ther work could be the foundation of better molecular diagnostic tools in the future.
Most strains of E. coli are harmless, but some can cause diarrhea or urinary tract infections and—if they enter the blood—even bloodstream infections and life-threatening sepsis.
In a new study, a research team at Hannover Medical School in Germany has found that E. coli has a significant genetic variation that contributes to the transition between the harmless life in the intestine and the pathogenic form. In addition, the researchers noted that the species has evolved toward causing disease increasingly 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,” said study author Marco Galardini.
For the study, published in PLoS Genetics, the team examined 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.
The researchers found significant differences between the disease-causing and the harmless isolates, both in their pangenomes and in their genetic backgrounds in terms of the presence of virulence-associated genes and antimicrobial resistance genes.
Using another commensal collection from 1980, the group also found that pathogenicity might have increased steadily from 1980 through 2000 to 2010.
“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,” said Galardini.
The most recent 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.