List of most notable antibiotic-resistant bacteria

Here’s a list of some of the most notable antibiotic-resistant bacteria, based on current global health priorities and threats as identified by organizations like the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC). These bacteria are recognized for their resistance to multiple antibiotics, posing significant challenges to treatment and public health. The list is not exhaustive but highlights key pathogens commonly cited as of March 22, 2025.

Critical Priority Antibiotic-Resistant Bacteria

These bacteria are often multidrug-resistant and pose severe risks, particularly in healthcare settings.

1. Acinetobacter baumannii (Carbapenem-resistant)

• Causes severe infections like pneumonia and bloodstream infections, often in hospitalized patients. Resistant to carbapenems, a last-resort antibiotic.

1. Pseudomonas aeruginosa (Carbapenem-resistant)

• Linked to infections in lungs, urinary tract, and wounds, especially in immunocompromised individuals. Known for resistance to multiple drugs, including carbapenems.

1. Enterobacteriaceae (Carbapenem-resistant, ESBL-producing)

• Includes species like Escherichia coli (E. coli), Klebsiella pneumoniae, Enterobacter spp., Serratia spp., and Proteus spp. Resistant to carbapenems and extended-spectrum beta-lactamases (ESBLs). Causes bloodstream infections, pneumonia, and urinary tract infections.

1. Klebsiella pneumoniae (Third-generation cephalosporin-resistant, Carbapenem-resistant)

• A standalone critical threat due to its high burden, particularly in low- and middle-income countries. Resistant to cephalosporins and carbapenems, causing pneumonia and sepsis.

High Priority Antibiotic-Resistant Bacteria

These pathogens are increasingly resistant and cause significant disease burdens.

5. Escherichia coli (Third-generation cephalosporin-resistant)

• Commonly causes urinary tract infections, food poisoning, and sepsis. Resistance to cephalosporins complicates treatment.

5. Staphylococcus aureus (Methicillin-resistant, MRSA)

• Known as MRSA, it resists methicillin and other antibiotics. Causes skin infections, pneumonia, and bloodstream infections, often in hospitals and communities.

5. Salmonella (Fluoroquinolone-resistant)

• Causes foodborne illnesses like typhoid fever. Resistance to fluoroquinolones limits treatment options, especially in regions with poor sanitation.

5. Shigella (Fluoroquinolone-resistant)

• Responsible for shigellosis (bloody diarrhea). Growing resistance to fluoroquinolones and other drugs is a concern in global health.

5. Neisseria gonorrhoeae (Cephalosporin-resistant, Fluoroquinolone-resistant)

• Causes gonorrhea, a sexually transmitted infection. Multidrug resistance makes it harder to treat.

5. Enterococcus faecium (Vancomycin-resistant, VRE)
   • Resistant to vancomycin, it causes infections in the bloodstream and urinary tract, primarily in healthcare settings.

Medium Priority and Other Notable Resistant Bacteria

These bacteria are resistant but currently pose a lesser immediate threat:

11. Streptococcus pneumoniae (Penicillin-non-susceptible)
    • Causes pneumonia, meningitis, and ear infections. Reduced susceptibility to penicillin is a growing issue.
12. Clostridioides difficile (C. difficile)
    • Naturally resistant to many antibiotics, it causes severe diarrhea, often after antibiotic use disrupts gut flora. Not on WHO’s priority list but a major CDC concern.
13. Mycobacterium tuberculosis (Rifampicin-resistant)
    • Causes tuberculosis (TB). Resistance to rifampicin, a key TB drug, is a critical global health issue, though often addressed separately from other bacterial resistance programs.

Additional Context

• The WHO’s 2024 Bacterial Priority Pathogens List (BPPL) emphasizes Acinetobacter baumannii, Pseudomonas aeruginosa, and resistant Enterobacteriaceae as top critical threats due to their multidrug resistance and prevalence in hospitals.
• The CDC’s 2019 AR Threats Report lists urgent threats like Carbapenem-resistant Acinetobacter, C. difficile, and Carbapenem-resistant Enterobacteriaceae (CRE), noting over 2.8 million resistant infections and 35,000 deaths annually in the U.S.
• Resistance patterns evolve, with some bacteria like Pseudomonas aeruginosa showing reduced global resistance (moved from critical to high priority in WHO’s 2024 list), yet still requiring vigilance.

This list reflects the current state of antibiotic resistance as of March 22, 2025, based on my continuously updated knowledge and aligned with reputable health organizations’ classifications. For the most specific or regional data, further research or local health authority reports might be needed.