Scientists have discovered that the bacterium infects the gut Clostridium difficile develops into two distinct species, with one group being highly adapted for hospitalization. Researchers at the Wellcome Sanger Institute, the London School of Hygiene and Tropical Medicine and collaborators have identified genetic changes in new species that allow it to thrive in a sugar-rich diet, avoid common hospital disinfectants and spread easily. Able to cause debilitating diarrhea, they say this new species began to emerge thousands of years ago and represents more than two-thirds of healthcare C. difficile infections.
Posted in The nature of genetics today (August 12), the largest genomic study to date C. difficile shows how bacteria can develop in a new species and demonstrates this C. difficile continues to evolve in response to human behavior. The results can help inform the patient's diet and control infections in hospitals.
C. difficile bacteria can infect the gut and are the leading cause of worldwide antibiotic-related diarrhea. While someone is healthy and does not take antibiotics, millions of "good" bacteria in the gut maintain C. difficile under control. However, antibiotics eradicate normal bacteria in the gut, leaving the patient vulnerable C. difficile infection in the gut. Then it is difficult to treat and can cause bowel inflammation and severe diarrhea.
Often found in hospital environments, C. difficile it forms persistent disputes that allow it to remain on the surface and spread easily among humans, making it a significant burden on the health system.
To understand how this bacterium develops, researchers collected and cultivated 906 strains of C. difficile isolated from humans, animals such as dogs, pigs and horses, and the environment. Through DNA sequencing of each strain and comparison and analysis of all genomes, the researchers found this C. difficile it is currently developing into two separate species.
Dr. Nitin Kumar, the first joint author at the Welcom Sanger Institute, said: "Our large-scale genetic analysis has allowed us to discover this C. difficile is currently forming a new species with one group specializing in hospitalization. This new species has been around for thousands of years, but this is the first time anyone has studied C. difficile genomes thus identify it. This particular bacterium was primed to take advantage of modern health practices and human diets before hospitals even existed. "
The researchers found that this emergent species called C. difficile Class A, accounting for approximately 70 percent of hospital patient samples. There are changes in genes that metabolize simple sugars, so researchers then investigate C. difficile in mice and found that emerging strains colonize mice better when their diet is enriched with sugar. In addition, differences in genes involved in spore formation have evolved, giving much greater resistance to common hospital disinfectants. These changes allow it to spread more readily to healthcare settings.
The analysis of dating revealed that while C. difficile Clade A first appeared about 76,000 years ago, and the number of different strains from this began to increase in the late 16th century, before modern hospitals were founded. This group has since flourished in hospital conditions with many strains that continue to adapt and develop.
Dr Trevor Lawley, senior author at the Welcom Sanger Institute, said: "Our study provides genome-wide and laboratory-based evidence that human lifestyles can drive bacteria to form new species so that they spread more effectively . We show that the strains of C. difficile bacteria continue to evolve in response to modern diets and health systems and reveal that focusing on diet and seeking new disinfectants could help combat this bacterium. "
Professor Brandon Rren, an author at the London School of Hygiene and Tropical Medicine, said: "This is the largest collection and analysis of C. difficile whole genomes from 33 countries around the world give us a whole new understanding of bacterial evolution. It reveals the importance of genomic monitoring of bacteria. Ultimately, this could help to understand how other dangerous pathogens develop, adapting to lifestyle changes and health regimes that can then inform health policies. "
Children can be naturally immunized after colonization of C. difficile in infancy
Adaptation of the cycle transmission host during the Clostridium difficile specification, The nature of genetics (2019). DOI: 10.1038 / s41588-019-0478-8
Diarrhea Bacteria Adapted to Hospitalization (2019, August 12)
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