New antibiotics needed: WHO priority pathogens

Posted on November 12, 2018   by Laura Cox

Bacteria are becoming resistant to antimicrobial medicines at an alarming rate. As antibiotics are used to treat infections, bacteria are able to adapt to survive, particularly when antibiotics are used inappropriately, or the full course is not completed.

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Resistant bacteria are capable of passing on the tools they use for resistance to other bacteria. As these beneficial genes are spread throughout bacterial populations there are concerns that, eventually, certain antibiotics will be rendered useless.

While this spread of resistance to antimicrobials is showing no sign of slowing down, development of new medicines has ground to a halt. To drive development into new antibiotics, the World Health Organization (WHO) published a list of 12 ‘Priority Pathogens’ in 2017. This is a group of pathogens they believe to pose the greatest threat to human health if emergence of antimicrobial resistance continues on its current trajectory.

‘New antibiotics needed: WHO priority pathogens of concern’ is an article collection in Microbial Genomics. The collection will include a review article for each pathogen on the list. Microbe Post will be delving further into each of these pathogens and the research being done to find new treatments; starting with fluoroquinolone-resistant Shigella.

What is Shigella?

Shigella is a genus of bacteria within the family Enterobacteriaceae. There are four species of Shigella, all of which can cause disease in humans.

Disease caused by Shigella bacteria is called shigellosis - or dysentery. It is estimated that worldwide, 160,000 people die of shigellosis each year. The unlucky 125 million people who are infected annually experience severe, sometimes bloody diarrhoea.

Shigellosis usually affects young children in low income, tropical countries. The recommended treatment is antibiotics, including beta-lactams, like penicillin, or more commonly, fluoroquinolones.

Fluoroquinolone resistance in Shigella

Resistance to fluoroquinolone-group antibiotics was first seen in Shigella in the early 2000’s. Resistance is at its most prevalent in South Asia and China, and has spread worldwide from these countries.

What are the alternatives?

At this stage, alternatives are running out. Shigella is resistant to not only fluoroquinolones, but a number of other front-line antibiotics, meaning it is increasingly difficult to treat.

Out of Asia: The independent rise and global spread of Fluoroquinolone-resistant Shigella is the first review in the New Antibiotics Needed collection. Written by Hao Chung The and Stephen Baker from The Oxford University Clinical Research Unit in Vietnam, the review discusses the emergence and spread of fluoroquinolone-resistant Shigella and looks into the genetic mechanisms the bacteria use to protect themselves from antimicrobials.