Size matters: for bacteria, smaller is better for causing superbug infections

  • New research discovers how a common hospital superbug called Enterococcus faecalis causes infections – currently poorly understood by scientists
  • Scientists uncover several complex mechanisms that enable bacteria to evade the immune system
  • Findings could be used to develop treatments for E. faecalis infections, such as heart valve infections and bacteraemia, which can be life-threatening

Scientists at the University of Sheffield have discovered a new insight into how one of the most common hospital superbugs causes infections – something which could be used to develop new antibiotic treatments.

Short cell chains escaping an immune systemThe study, led by researchers from the University of Sheffield’s Department of Molecular Biology and Biotechnology, investigated how Enterococcus faecalis – bacteria commonly found in the digestive tracts of humans and multi-resistant to antibiotics – can out-compete other microorganisms and cause life-threatening infections.

E. faecalis is frequently responsible for causing hospital-acquired infections such as urinary tract infections, heart valve infections and bacteraemia, however scientists currently have a poor understanding of how this happens.

Now, the University of Sheffield-led research team has discovered several complex mechanisms controlling the maintenance of the distinctive shape of E. faecalis that forms cell pairs or short chains of cells.

The team has revealed that the formation of short chains of cells is a crucial factor in stopping bacteria being recognised as a threat by the immune system. This then enables infection to spread.

Dr Stéphane Mesnage, who led the research from the University of Sheffield, said: “Our study shows that the formation of short chains of cells by E. faecalis is a critical step for causing an infection. Bacteria that form long chains of cells are efficiently recognised and engulfed by the host immune system, whereas short chains of cells can evade host immune cells and spread in the host to cause infection.

E. faecalis is an opportunistic pathogen. It is naturally resistant to a wide range of antibiotics, including synthetic penicillin derivatives. Following an antibiotic treatment, E. faecalis can out-compete other microorganisms to cause infection. Our work suggests that targeting the mechanisms controlling the formation of short chains of cells could be a novel strategy for developing new treatments to fight E. faecalis infections.”

The research, Bacterial size matters: multiple mechanisms controlling septum cleavage and diplococcus formation are critical for the virulence of the opportunistic pathogen Enterococcus faecalis, is published in PLOS Pathogens: Bacterial size matters (PLOS Pathogens journal)

Findings from the study build on the University of Sheffield’s position at the forefront of world-class research into infectious diseases. Scientists at the University are developing radical solutions to the global threat of disease and antimicrobial resistance as part of signature research projects such as Florey, Imagine and the Sheffield Antimicrobial Resistance Network (SHAMROK).

The University is also training the next generation of highly skilled scientists through its undergraduate and postgraduate programmes to find exciting new approaches to bioscience and tackle some of the world’s biggest biomedical problems.

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