How the list works
WHO scored candidate pathogens on mortality, incidence, transmissibility, treatability and the state of the drug pipeline, then grouped them into three tiers. The 2024 list contains 15 antibiotic-resistant pathogen groups. The top-scoring single bacterium was carbapenem-resistant Klebsiella pneumoniae.
The most dangerous — few or no reliable treatments
- Carbapenem-resistant Acinetobacter baumannii — an intensive-care menace that survives on surfaces for weeks and causes ventilator-associated pneumonia and bloodstream infections.
- Carbapenem-resistant Enterobacterales (including Klebsiella pneumoniae and E. coli) — resistant to the “last resort” carbapenems; mortality in bloodstream infections can approach 50%.
- Third-generation cephalosporin-resistant Enterobacterales — ESBL-producing bacteria now common even in community infections such as UTIs.
- Rifampicin-resistant Mycobacterium tuberculosis — drug-resistant TB, elevated to the critical tier in 2024. About 400,000 people develop multidrug-resistant or rifampicin-resistant TB each year, and well under half are diagnosed and started on effective treatment.
These are all Gram-negative bacteria (except TB) — armoured with a double membrane that keeps many drugs out, and adept at swapping resistance plasmids.
Serious threats with rising resistance
- MRSA (methicillin-resistant Staphylococcus aureus) — directly caused more than 100,000 deaths worldwide in 2019.
- Vancomycin-resistant Enterococcus faecium (VRE) — a hardy hospital pathogen of the immunocompromised.
- Carbapenem-resistant Pseudomonas aeruginosa — a versatile opportunist in burns, ICUs and cystic fibrosis.
- Fluoroquinolone-resistant Salmonella Typhi and non-typhoidal Salmonella — extensively drug-resistant typhoid is spreading in South Asia.
- Fluoroquinolone-resistant Shigella — a major cause of childhood diarrhoeal death.
- Cephalosporin- and/or fluoroquinolone-resistant Neisseria gonorrhoeae — gonorrhoea strains resistant to ceftriaxone, the final reliable oral-era option, have been detected in several countries, raising the spectre of untreatable gonorrhoea.
Significant, especially for vulnerable groups
- Macrolide-resistant Streptococcus pneumoniae — pneumonia and meningitis, hitting children and the elderly hardest.
- Ampicillin-resistant Haemophilus influenzae — respiratory and bloodstream infections in children.
- Macrolide-resistant Group A and penicillin-resistant Group B Streptococci — from strep throat and sepsis to newborn infections.
Beyond bacteria: resistant fungi and more
AMR is broader than bacteria. Three examples worth knowing:
- Candida auris — a yeast unknown before 2009, now spreading in hospitals on every inhabited continent. It is often resistant to one or more of the three main antifungal classes, sometimes all of them, and is hard to eradicate from hospital environments. WHO lists it in the critical group of its Fungal Priority Pathogens List (2022).
- Drug-resistant malaria — artemisinin partial resistance, first seen in Southeast Asia, has now emerged in East Africa.
- Drug-resistant HIV — rising background resistance to some first-line drugs complicates treatment programmes.
Why a “priority list” matters
The list is not a ranking of scariness for its own sake — it steers money and science. Governments, funders and companies use it to decide which pathogens new antibiotics, diagnostics and vaccines should target first, the way the first list (2017) helped focus the pipeline on Gram-negative bacteria. The 2024 update's blunt message: the pathogens with the fewest treatment options — carbapenem-resistant Gram-negatives and drug-resistant TB — still have the thinnest pipelines. What is being done about that is the subject of the Innovation page.
Sources for this page
- WHO, “Bacterial Priority Pathogens List, 2024” — who.int / iris.who.int
- “The WHO Bacterial Priority Pathogens List 2024: a prioritisation study”, The Lancet Infectious Diseases, 2025 — pmc.ncbi.nlm.nih.gov/articles/PMC12367593/
- “The 2024 WHO bacterial priority pathogens list: a critical evolution from a global One Health perspective”, 2025 — sciencedirect.com
- WHO, “Fungal Priority Pathogens List”, 2022; WHO Global Tuberculosis Report (drug-resistant TB figures) — who.int
- Murray et al., The Lancet, 2022 (MRSA mortality) — thelancet.com