Dangerous dozen: WHO lists threats to public health

By Joseph James Whitworth

- Last updated on GMT


Related tags Antimicrobial resistance Antibiotic resistance

Food poisoning bacteria feature in a World Health Organization (WHO) list of pathogens that pose the greatest threat to human health due to antibiotic resistance.

It is divided into critical, high and medium priority categories depending on the urgency for antibiotics.

Enterobacteriaceae, carbapenem-resistant, ESBL-producing features in the critical section, while Staphylococcus aureus, methicillin-resistant, vancomycin-intermediate and resistant; Campylobacter spp. and Salmonella (both fluoroquinolone-resistant) are in the high category.

The most critical group are multidrug resistant bacteria including various Enterobacteriaceae (including Klebsiella, E. coli, Serratia and Proteus) which can cause severe infections in the bloodstream and pneumonia.

They have become resistant to a large number of antibiotics, including carbapenems and third generation cephalosporins - the best available way to treat multi-drug resistant bacteria.
Increasingly resistant

The second and third tiers - the high and medium priority categories - contain increasingly drug-resistant bacteria that cause more common diseases such as food poisoning due to Salmonella.

Shigella spp. (fluoroquinolone-resistant) is a medium priority.

Dr Marie-Paule Kieny, WHO’s assistant director-general for health systems and innovation, said: “Antibiotic resistance is growing, and we are fast running out of treatment options. If we leave it to market forces alone, the new antibiotics we most urgently need are not going to be developed in time.”

Two EU agencies also recently said antimicrobial resistance (AMR) poses a serious threat to public health.

Bacteria in humans, animals and food showed resistance to widely used antimicrobials, according to the European Food Safety Authority (EFSA) and the European Centre for Disease Prevention and Control (ECDC).

Mike Catchpole, chief scientist at ECDC, said: “It is of particular concern that some common types of Salmonella in humans, such as monophasic Salmonella Typhimurium, exhibit extremely high multi-drug resistance.”

Vytenis Andriukaitis, EU Commissioner for Health and Food Safety, said there have been “substantial” efforts to stop the rise of antimicrobial resistance but it was not enough.

“We must be quicker, stronger and act on several fronts. This is why the Commission will launch a new action plan this summer that will give a new framework for future coordinated actions to reduce the spread of antimicrobial resistance.”

John FitzGerald of RUMA, the agricultural and food industry alliance, welcomed the report.

“We hope that the generally lower levels of resistance found in the UK reflect, in part, the responsible use guidelines for farm animals we have had in place through RUMA for the past 20 years.”

However, FitzGerald said while cutting back on antibiotic use should reduce the risk of resistance, there was not always a direct relationship.

This report found very low levels of resistance to carbapenems in pigs and pig meat, yet carbapenems are neither authorised nor used in food-producing animals. But this doesn’t mean we should lose focus on reductions​,” he added.

Reaction: Scale of problem

WHO said it highlights the threat of gram-negative bacteria that are resistant to multiple antibiotics and can pass along genetic material that allows other bacteria to become drug-resistant.

WHO priority pathogens list for R&D of new antibiotics

Priority 1: Critical

1. Acinetobacter baumannii​, carbapenem-resistant
2. Pseudomonas aeruginosa​, carbapenem-resistant
3. Enterobacteriaceae​, carbapenem-resistant, ESBL-producing

Priority 2: high

4. Enterococcus faecium​, vancomycin-resistant
5. Staphylococcus aureus​, methicillin-resistant, vancomycin-intermediate and resistant
6. Helicobacter pylori​, clarithromycin-resistant
7. Campylobacter​ spp., fluoroquinolone-resistant
8. Salmonellae, fluoroquinolone-resistant
9. Neisseria gonorrhoeae​, cephalosporin-resistant, fluoroquinolone-resistant

Priority 3: MEDIUM

10. Streptococcus pneumoniae​, penicillin-non-susceptible
11. Haemophilus influenzae​, ampicillin-resistant
12. Shigella​ spp., fluoroquinolone-resistant

It was created to guide and promote research and development (R&D) of new antibiotics.

The list was developed with the division of infectious diseases at the University of Tübingen, Germany, using a multi-criteria decision analysis technique vetted by international experts.

“New antibiotics targeting this priority list of pathogens will help to reduce deaths due to resistant infections around the world,”​ says Prof Evelina Tacconelli, head of the division of infectious diseases at the university.

Associate Professor Peter Speck, from the School of Biological Sciences at Flinders University, said phage therapy is not a new idea but has been overlooked in the Western world in favour of the now-failing antibiotics.

"There is strong evidence that the antibiotic era is drawing to a close. Bacterial pathogens, such as Staphylococcus aureus “golden staph”, are becoming increasingly resistant to all antibiotics,” ​he said.

“The UK Government O’Neill Report estimates that by 2050 antimicrobial resistance will kill 10 million people per year, at a total economic cost of US$100 trillion.

“For context, cancer kills eight million people per year worldwide. While the antibiotic discovery pipeline is virtually empty, bacteriophages represent a potential solution in many clinical settings.”

Michael Gillings, professor of molecular evolution in the department of biological sciences at Macquarie University, said the bacteria in the list are deadly, difficult to cure and spread easily between people and animals.

“Most importantly, they are resistant to the antibiotics that we normally use to kill bacterial infections.  Unless we do something soon, it is estimated that the death toll for antibiotic resistant infections might reach 10 million per year by 2050; more than the global toll for cancer.”

Kirsty Buising, associate professor, deputy director of the National Centre for Antimicrobial Stewardship (NCAS) said it was important to develop antimicrobials to treat infections caused by pathogens resistant to current antimicrobial drugs.

However, we also need to focus on ensuring that the antimicrobial drugs that we do have remain effective in the future,” ​she said.

“We know that many antimicrobial drugs are currently being used in inappropriate ways, indeed sometimes in situations where they are completely unnecessary. This is contributing to the growing problem of antimicrobial resistance amongst microbial pathogens.”

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