New Antibiotics Needed: Enterococcus faecium

Posted on November 20, 2019   by Matt Bassett

As part of World Antibiotic Awareness Week, we are continuing our New Antibiotics Needed blog series detailing the twelve pathogens thought by the World Health Organisation (WHO) to pose the greatest threat to human health.

Enterococcus faecium

Enterococcus faecium is recognised as a globally important opportunistic pathogen. As with other pathogens on the list, such as Pseudomonas aeruginosa, E. faecium causes particular problems in hospitalised individuals. In the United States one of the major causes of device associated infections (e.g. central lines, catheters or ventilators) are due to resistant strains of E. faecium.

Symptoms caused by E. faecium depend on the site of infection, e.g. bloodstream, wound or urinary tract. Wound infections, usually associated with catheters or surgery, can cause soreness, swelling and fluid leakage. Urinary tract infections can cause pain or burning sensations while urinating, fatigue and lower back or abdominal pain. Bloodstream infections can cause fever, chills, vomiting and diarrhoea.

© iStock/peterspiro

Drug resistance

Bacteria in the genus Enterococcus have resistance to a number of antimicrobial classes, however over the recent decades E. faecium has shown an increase in rate of acquired resistance to antibiotics, including to the antibiotic vancomycin. Vancomycin has been on the market since 1954 and is on the WHO’s list of essential medicines – the most effective and safe medicines needed in a health system.

Healthcare-associated pathogens

E. faecium is one of the many pathogens that fall under the umbrella term of healthcare associated pathogens/infections. But why do hospitals and other health care facilities have a whole group of pathogens named after them? Many of the pathogens under this term only cause real problems in immune-suppressed individuals, for example those weakened by illness or surgery. Many patients in hospitals will fall under these categories, making it easy for pathogens to cause infections. Also, there is a chance that health care professionals may inadvertently transfer pathogens from patients carrying diseases.

Disinfectant tolerance

© iStock/Natali_Mis

E. faecium is worrying as it’s highly adaptive and evolves rapidly, for example recent studies have been published suggesting that, as well as drug resistance, E. faecium is developing tolerance to alcohol-based disinfectants. Other studies have also shown that repeat exposure to other antiseptics, such as chlorhexidine, can lead to reduced susceptibility. These disinfectants and antiseptics are vital in preventing the spread of pathogens in hospitals and care facilities, the fact that there are bacteria evolving resistance to them is very worrying.

Genomics of vancomycin-resistant Enterococcus faecium is featured in the New Antibiotics Needed collection in Microbial Genomics and is written by Claire Gorrie, Charlie Higgs, Glen Carter, Timothy P. Stinear and Benjamin Howden from the University of Melbourne. The review discusses the mechanisms of vancomycin resistance, the clonal structure of E. faecium and clinical isolated and emerging mechanisms of resistance to last-line antibiotics.

More from our New Antibiotics Needed blog series:
Haemophilus influenzae
Neisseria gonorrhoeae
Acinetobacter baumannii