AUG 17, 2019 10:07 AM PDT

A Pathogen That Has Evolved to Spread in Hospitals

WRITTEN BY: Carmen Leitch

The bacterium Clostridium difficile is the primary cause of infections that are acquired in hospital settings; it causes diarrhea and intestinal inflammation. The microbe is often found in the human gut, but when people are healthy, the many other bacteria in the gut microbiome keep the growth of C. difficile contained. People in hospitals often need to take rigorous courses of antibiotics that can dramatically reduce the number of beneficial microbes in the gut, however, giving C. difficile a chance to grow.

A digitally-colorized scanning electron microscopic image depicting a group of Clostridium difficile bacteria, cultured from a stool sample after an outbreak. / Credit: CDC/ Lois S. Wiggs

Researchers have now found that the C. difficile bacterium is evolving. One species is particularly adapted to hospital environments where it can easily move around. Reporting in Nature Genetics, the scientists identified changes in the bacterial genomes that have made it evade disinfectants, grow well, and flourish on a sugar-rich diet that’s typical of western foods. The evolution of the bacterium is strongly influenced by human behaviors.

"Our study provides genome and laboratory-based evidence that human lifestyles can drive bacteria to form new species so they can spread more effectively," noted the senior study author Dr. Trevor Lawley of the Wellcome Sanger Institute. "We show that strains of C. difficile bacteria have continued to evolve in response to modern diets and healthcare systems and reveal that focusing on diet and looking for new disinfectants could help in the fight against this bacteria."

In this study, the scientists gathered 906 different strains of C. difficile that were isolated from a variety of species including humans, dogs, horses, and pigs. They grew the bacteria and sequenced their genomes, and found the emergence of the two separate species. This research is thought to be the most comprehensive genetic study of the pathogen.

"Our large-scale genetic analysis allowed us to discover that C. difficile is currently forming a new species with one group specialized to spread in hospital environments," said the co-first author of the report, Dr. Nitin Kumar of the Wellcome Sanger Institute. "This emerging species has existed for thousands of years, but this is the first time anyone has studied C. difficile genomes in this way to identify it. This particular bacteria was primed to take advantage of modern healthcare practices and human diets before hospitals even existed."

It’s estimated that this bacterium began to appear around 76,000 years ago and may now be to blame for more than two-thirds of healthcare-related C. difficile infections. As modern hospitals were founded in the 16th century, the number of strains of the microbe increased.

After finding the emerging species, termed C. difficile clade A, the scientists showed that the bacterium grew better in mice when it was exposed to a diet that contained sugar. Bacterial genes that enable a microbe to grow tough colonies called spores were also different and gave the spores the power to resist disinfectants. This research can help improve infection control in hospitals and patients.

"This largest ever collection and analysis of C. difficile whole genomes, from 33 countries worldwide, gives us a whole new understanding of bacterial evolution. It reveals the importance of genomic surveillance of bacteria," said study co-author Professor Brendan Wren of the London School of Hygiene & Tropical Medicine. "Ultimately, this could help [us] understand how other dangerous pathogens evolve by adapting to changes in human lifestyles and healthcare regimes which could then inform healthcare policies."


Sources: Science Daily via Wellcome Trust Sanger Institute, Nature Genetics

About the Author
  • Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
MAY 27, 2021
Neuroscience
Research Less Likely to Be True is Cited More
MAY 27, 2021
Research Less Likely to Be True is Cited More
Researchers from the University of California San Diego have found that non-replicable data is cited 153 times more ofte ...
JUN 10, 2021
Immunology
Decoding the Immune System's Language
JUN 10, 2021
Decoding the Immune System's Language
Scientists at UCLA have decoded the “vocabulary” of immune cells—six distinct signals used as flares t ...
JUN 26, 2021
Space & Astronomy
Cardiac Atrophy Findings May Aid Astronauts in Long Space Flights
JUN 26, 2021
Cardiac Atrophy Findings May Aid Astronauts in Long Space Flights
Researchers led by Cincinnati Children’s Hospital Medical Center have discovered the molecular process behind a da ...
JUN 27, 2021
Cell & Molecular Biology
Organoids Reveal Common Mechanism Underlying Rare Disorders
JUN 27, 2021
Organoids Reveal Common Mechanism Underlying Rare Disorders
Genetic testing has shown that mutations in a gene called HUWE1 are connected to rare syndromes that cause developmental ...
JUL 14, 2021
Genetics & Genomics
Genetic Tools Can Aid Endangered Species
JUL 14, 2021
Genetic Tools Can Aid Endangered Species
Nature is in decline; the planet has lost a tremendous amount of biodiversity over the past few years due to human actio ...
JUL 18, 2021
Genetics & Genomics
Researchers Find Strange 'Borg' DNA - It's Assimilating
JUL 18, 2021
Researchers Find Strange 'Borg' DNA - It's Assimilating
Our environment is full of DNA molecules. While researchers have become concerned about DNA waste material that's ac ...
Loading Comments...