The World Health Organization (WHO) has just published its new list of priority bacterial pathogens for the year 2024. This list identifies 15 families of antibiotic-resistant bacteria, classified into three categories (critical, high and medium) for facilitate priority setting. This classification provides guidelines for the development of new treatments needed to stop the spread of antimicrobial resistance.
Antimicrobial resistance occurs when these medications lose their effectiveness against bacteria, viruses, fungi, and parasites. This results in the development of more serious diseases and a greater risk of spread, which increases morbidity and mortality. The main cause of this resistance is the excessive and inappropriate use of antimicrobials. The updated list incorporates new evidence and expert information that will be useful for the research and development of new antibiotics, international coordination and the promotion of innovation.
“To develop the list of priority bacterial pathogens, the global burden of infections due to drug-resistant bacteria has been determined and their impact on public health has been analyzed. Therefore, this list is essential to guide investment and overcome the obstacles that make it difficult to obtain and access new antibiotics. The threat of antimicrobial resistance has increased since the publication of the first list in 2017, which undermines the effectiveness of many antibiotics and can undo many achievements of modern medicine,” explained Yukiko Nakatani, Acting Deputy Director General of WHO Antimicrobial Resistance.
Prevent, diagnose and treat infections correctly
Critical priority pathogens, such as Gram-negative bacteria resistant to last-resort antibiotics and Mycobacterium tuberculosis resistant to rifampicin, are especially dangerous due to the incidence of the diseases they cause and their ability to resist treatments and transfer resistance to other bacteria. Gram-negative bacteria can develop new forms of resistance and transmit resistant genetic material to other bacteria.
High-priority pathogens include Salmonella and Shigella, which cause high morbidity and mortality in low- and middle-income countries, as well as Pseudomonas aeruginosa and Staphylococcus aureus, which cause significant problems in hospital settings.
Other high-priority pathogens, such as Neisseria gonorrhoeae and multidrug-resistant Enterococcus faecium, present specific public health challenges, such as persistent infections and resistance to multiple antibiotics, requiring public health interventions and targeted studies.
In the medium priority category are group A and B streptococci (added in the 2024 list), Streptococcus pneumoniae and Haemophilus influenzae, which cause a high burden of disease. These pathogens need increased surveillance, especially in vulnerable populations such as children and the elderly in regions with limited resources.
“The threat of antimicrobial resistance has increased since the publication of the first list in 2017, which undermines the effectiveness of many antibiotics and can undo many achievements of modern medicine”
“Antimicrobial resistance challenges our ability to effectively treat infections that cause high morbidity and mortality, such as tuberculosis, leading to serious illness and increased mortality rates,” said Dr. Jérôme Salomon, Deputy Director General of WHO for Universal Health Coverage/Communicable and Non-Communicable Diseases.
The 2024 list also highlights the need for a comprehensive public health approach to combating antimicrobial resistance, including universal access to quality and affordable measures to prevent, diagnose and treat infections correctly, as explained in the Public Health Approach document. WHO focuses on people to combat antimicrobial resistance. This is essential to mitigate the impact of antimicrobial resistance on public health and the economy.
How the 2024 list varies compared to that of 2017
The 2024 list eliminates five combinations of pathogens and antibiotics present on the 2017 list and includes four new combinations. Third-generation cephalosporin-resistant Enterobacteriaceae stand out in a separate group within the critical priority category, underscoring their burden of morbidity and mortality and the need for targeted interventions, especially in low- and middle-income countries.
Additionally, carbapenem-resistant Pseudomonas aeruginosa infection has been reclassified from critical to high priority, reflecting recent reports of declining resistance globally. However, it remains crucial to invest in R&D and prevention and control strategies due to the high burden of this infection in certain regions.
The WHO list of priority bacterial pathogens for 2024 includes these bacteria:
Critical priority:
- Acinetobacter baumannii resistant to carbapenems.
- Enterobacteriaceae resistant to third generation cephalosporins.
- Enterobacteriaceae resistant to carbapenems.
- Rifampicin-resistant Mycobacterium tuberculosis (which has been included after carrying out an independent analysis with parallel adapted criteria and after the subsequent application of an adapted analysis matrix to decide based on several criteria).
High priority:
- Salmonella Typhi resistant to fluoroquinolones.
- Shigella spp. resistant to fluoroquinolones.
- Vancomycin-resistant Enterococcus faecium.
- Pseudomonas aeruginosa resistant to carbapenems.
- Non-typhoid salmonellae resistant to fluoroquinolones.
- Neisseria gonorrhoeae resistant to third generation cephalosporins and/or fluoroquinolones.
- Methicillin-resistant Staphylococcus aureus.
Medium priority:
- Macrolide-resistant group A streptococci.
- Macrolide-resistant Streptococcus pneumoniae.
- Haemophilus influenzae resistant to ampicillin.
- Macrolide-resistant group B streptococci.
The changes reflect the dynamics of antimicrobial resistance, which requires adaptation of interventions. This list should be adapted to national and regional contexts, considering local variations in pathogen distribution and resistance burden. For example, unlisted drug-resistant Mycoplasma genitalium poses growing problems in some parts of the world.
Source: World Health Organization (WHO)
