Bacteria use antimicrobial agent to kill competition
Hospitalized patients are often given antibiotics, which
reduces the diversity of bacteria in their microbiomes. It also
allows drug-resistant strains to gain a foothold and take over.
Enterococcus faecium is a gut bacterium that can cause lethal
infections if it gets into the bloodstream. Vancomycin-resistant E.
faecium (VREfm), which is resistant to vancomycin and multiple
other antibiotics, is a growing problem in healthcare settings.
Populations of VREfm within healthcare systems are known to
change over time. But the factors driving these changes aren’t
well understood.
NIH-supported researchers at the University of Pittsburgh
Medical Center have been collecting and sequencing bacterial
DNA from hospitalized patients through the Enhanced Detection
System for Healthcare-Associated Transmission (EDS-HAT). This
helps clinicians to recognize and stop potential outbreaks. As part
of this effort, researchers collected more than 700 VREfm
samples between 2017 and 2022. A team at the university, led by
Dr. Daria Van Tyne, used data from these samples to track
VREfm evolution. Their findings appeared in Nature Microbiology
on March 21, 2025.
Genome sequencing of the samples identified 42 different
genetic lineages, or strains, of VREfm. Almost half of the samples
were closely related to at least one other sample. This suggests a
high level of transmission within the hospital. Before 2020, about
a third of the samples belonged to the strain ST17. From 2020
onward, two new strains, ST80 and ST117, began to take over.
By the end of 2022, these two strains made up more than 80% of
all samples, while ST17 was not detected.
The researchers found that ST80 and ST117 could kill ST17,
but not vice versa. Further examination revealed that ST80 and
ST117, but not ST17, produce an antimicrobial peptide (a short
chain of amino acids) called bacteriocin T8. Both in laboratory
cultures and the guts of mice, strains that made bacteriocin T8
outcompeted strains that didn’t.
Next, the team analyzed more than 15,000 publicly available
VREfm genomes collected worldwide between 2002 and 2022.
They saw the same trend, with ST17 replaced by ST80 and
ST117. This suggests that the changes observed in a single
hospital reflected global trends.
Disponível em: https://www.nih.gov/news-events/nih-research-matters/bacteria-use-antimicrobialagent-kill-competition. Acesso em: 3 abr. 2025.
According to the text, how do strains ST80 and ST117
outcompete ST17?
