WHO Updates Bacterial Priority Pathogens List to Combat Antimicrobial Resistance

AMR arises when bacteria, viruses, fungi, and parasites resist existing medicines, escalating the risk of disease spread, illness, and deaths.

The World Health Organization (WHO) released its updated Bacterial Priority Pathogens List (BPPL) 2024, highlighting 15 families of antibiotic-resistant bacteria categorized as critical, high, and medium priorities. This list aims to guide the development of new treatments and curb the spread of antimicrobial resistance (AMR).

AMR arises when bacteria, viruses, fungi, and parasites resist existing medicines, escalating the risk of disease spread, illness, and deaths. Misuse and overuse of antimicrobials drive AMR, which undermines the efficacy of many modern medical treatments. The updated BPPL incorporates new evidence to direct research and development (R&D) efforts for new antibiotics and foster international cooperation to spur innovation.

“By mapping the global burden of drug-resistant bacteria and assessing their impact on public health, this list is key to guiding investment and grappling with the antibiotics pipeline and access crisis," stated Dr. Yukiko Nakatani, WHO’s Assistant Director-General for Antimicrobial Resistance ad interim. She noted the intensified threat of AMR since the first BPPL release in 2017, which jeopardizes modern medical advancements.

The critical priority pathogens include gram-negative bacteria resistant to last-resort antibiotics and Mycobacterium tuberculosis resistant to rifampicin, posing significant global threats due to their treatment resistance and potential to spread. Gram-negative bacteria are particularly concerning as they can pass on genetic material that confers drug resistance to other bacteria.

High priority pathogens such as Salmonella, Shigella, Pseudomonas aeruginosa, and Staphylococcus aureus pose significant challenges, especially in low- and middle-income countries and healthcare settings. Pathogens like antibiotic-resistant Neisseria gonorrhoeae and Enterococcus faecium present unique public health challenges, including persistent infections and multi-drug resistance, requiring targeted research and interventions.

Medium priority pathogens include Group A and B Streptococci (both new to the 2024 list), Streptococcus pneumoniae, and Haemophilus influenzae. These pathogens, affecting vulnerable populations such as children and the elderly, necessitate increased attention, particularly in resource-limited settings.

“Antimicrobial resistance jeopardizes our ability to effectively treat high-burden infections, such as tuberculosis, leading to severe illness and increased mortality rates," emphasized Dr. Jérôme Salomon, WHO's Assistant Director-General for Universal Health Coverage, Communicable and Noncommunicable Diseases.

The BPPL 2024 stresses the need for a comprehensive public health approach to AMR, including universal access to quality and affordable prevention, diagnosis, and treatment measures, as outlined in WHO’s People-centered approach to addressing AMR and core package of AMR interventions. This holistic approach is crucial for mitigating AMR’s public health and economic impacts.

Significant changes from the 2017 list include the removal of five pathogen-antibiotic combinations and the addition of four new combinations. Third-generation cephalosporin-resistant Enterobacterales now appear as a standalone critical priority item, emphasizing their burden and the need for targeted interventions. Carbapenem-resistant Pseudomonas aeruginosa has been moved from critical to high priority due to recent decreases in global resistance, though continued investment in R&D remains essential.

The 2024 BPPL includes the following bacteria:

Critical priority:

• Acinetobacter baumannii, carbapenem-resistant
• Enterobacterales, third-generation cephalosporin-resistant
• Enterobacterales, carbapenem-resistant
• Mycobacterium tuberculosis, rifampicin-resistant

High priority:

• Salmonella Typhi, fluoroquinolone-resistant
• Shigella spp., fluoroquinolone-resistant
• Enterococcus faecium, vancomycin-resistant
• Pseudomonas aeruginosa, carbapenem-resistant
• Non-typhoidal Salmonella, fluoroquinolone-resistant
• Neisseria gonorrhoeae, third-generation cephalosporin- and/or fluoroquinolone-resistant
• Staphylococcus aureus, methicillin-resistant

Medium priority:

• Group A streptococci, macrolide-resistant
• Streptococcus pneumoniae, macrolide-resistant
• Haemophilus influenzae, ampicillin-resistant
• Group B streptococci, penicillin-resistant

The 2024 updates reflect AMR's evolving nature, necessitating tailored interventions. Tailoring the BPPL to regional contexts can address local variations in pathogen distribution and AMR burden, highlighting the global challenge of antibiotic-resistant Mycoplasma genitalium in some areas.