C. Difficile Bacteria Adapted to Spread in Hospitals

While someone is healthy and not taking antibiotics, millions of 'good' bacteria in the gut keep the C. difficile under control.

However, antibiotics wipe out the normal gut bacteria, leaving the patient vulnerable to C. difficile infection in the gut. This is then difficult to treat and can cause bowel inflammation and severe diarrhea. Often found in hospital environments, C. difficile forms resistant spores that allow it to remain on surfaces and spread easily between people, making it a significant burden on the healthcare system.

Scientists at the Wellcome Trust Sanger Institute (Hinxton, UK) and their colleagues collected and cultured 906 strains of C. difficile isolated from humans, animals, such as dogs, pigs and horses, and the environment. By sequencing the DNA of each strain, and comparing and analyzing all the genomes, they discovered that C. difficile is currently evolving into two separate species.

The team found that found that this emerging species, named C. difficile clade A, made up approximately 70% of the samples from hospital patients. It had changes in genes that metabolize simple sugars, so they then studied C. difficile in mice, and found that the newly emerging strains colonized mice better when their diet was enriched with sugar. It had also evolved differences in the genes involved in forming spores, giving much greater resistance to common hospital disinfectants. These changes allow it to spread more easily in healthcare environments.

Trevor Lawley, PhD, a molecular microbiologist and senior author of the study, said, “Our study provides genome and laboratory based evidence that human lifestyles can drive bacteria to form new species so they can spread more effectively. 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 these bacteria.” The study was published on August 12, 2019, in the journal Nature Genetics.

Related Links:
Wellcome Trust Sanger Institute