Linking peptides to the antibiotic amikacin created conjugates that restored antibiotic activity against 77% of drug-resistant Klebsiella strains when combined with polymyxin B.
77% synergy against resistant strainsPeptide-amikacin conjugates combined with polymyxin B overcame resistance in 77% of 31 Klebsiella pneumoniae strains, including those resistant to virtually all available antibiotics.
What the researchers found
Peptide-linked amikacin conjugates showed powerful synergy with polymyxin B against extensively drug-resistant and pandrug-resistant Klebsiella pneumoniae. Of 31 resistant strains tested, 77% showed synergy when peptide-amikacin conjugates containing tryptophan and cysteine were combined with polymyxin B, including strains carrying multiple resistance enzymes (AMEs and RMTases). The peptide-linked compounds maintained similar mammalian cell toxicity as unmodified amikacin but were dramatically more synergistic with polymyxin B against resistant bacteria.
Why it matters
Drug-resistant Klebsiella pneumoniae is at the top of the WHO's critical priority pathogen list, and existing antibiotics are rapidly losing effectiveness. By linking amino acid peptides to the antibiotic amikacin, researchers created a new class of conjugates that restore antibiotic activity against bacteria that are resistant to virtually everything. This peptide-modification strategy could be a lifeline against the growing threat of untreatable infections.
The numbers in context
31 K. pneumoniae strains · 77% showed synergy · peptides with tryptophan and cysteine most effective · active against AME and RMTase carriers · pandrug-resistant strains included
How the study worked
Researchers chemically synthesized a library of peptide-linked amikacin derivatives, attaching amino acids with different properties (positively charged, sulfur-containing, or aromatic side chains). These conjugates were tested alone and in combination with polymyxin B against 31 Klebsiella pneumoniae strains with various resistance mechanisms. Synergy was assessed using standard antimicrobial susceptibility testing, and mammalian cell toxicity was evaluated.
Who was studied
31 Klebsiella pneumoniae strains including extensively drug-resistant and pandrug-resistant isolates
What this study cannot tell us
This is an in vitro study; the peptide-amikacin conjugates have not been tested in animal models or humans. Pharmacokinetic properties (absorption, distribution, metabolism) of the conjugates are unknown. The study focused on Klebsiella pneumoniae — activity against other critical priority pathogens needs testing. The combination still requires polymyxin B, which has its own toxicity concerns.
How to read the evidence
This is a preclinical in vitro study demonstrating proof-of-concept for peptide-antibiotic conjugates. While the results are promising across a diverse panel of resistant strains, animal model and clinical validation are needed before therapeutic application.
When this study was published
Published in 2026, this represents cutting-edge research in peptide-antibiotic hybrid drug design, addressing the critical and growing threat of pandrug-resistant bacteria.
The bigger picture
Antimicrobial resistance is projected to cause millions of deaths annually if new solutions aren't found. This study demonstrates that peptide conjugation — attaching peptide fragments to existing antibiotics — can overcome even the most extreme resistance mechanisms. It's part of a broader trend in peptide-antibiotic hybrid drug design that could extend the useful life of our existing antibiotic arsenal.
Questions still open
- Will the peptide-amikacin conjugates maintain their synergistic activity in animal infection models?
- Can this peptide conjugation strategy be applied to other aminoglycosides or antibiotic classes to overcome resistance?
- What is the mechanism by which peptide modification enhances synergy with polymyxin B — does it improve bacterial membrane penetration?
Common questions
How does linking peptides to an antibiotic help overcome drug resistance?
Why were tryptophan and cysteine the most effective peptide modifications?
Read the original research
Broad-Spectrum Activity of Peptide-Linked Amikacin Conjugates in Synergy with Polymyxin B against Extensively Drug-Resistant and Pandrug-Resistant Bacteria.
ACS infectious diseases, 12(1), 298-313
Citation
Story, Sandra; Sharma, Anindra; Maiti, Krishnagopal; Arya, Dev P. (2026). Broad-Spectrum Activity of Peptide-Linked Amikacin Conjugates in Synergy with Polymyxin B against Extensively Drug-Resistant and Pandrug-Resistant Bacteria.. ACS infectious diseases, 12(1), 298-313. https://doi.org/10.1021/acsinfecdis.5c00798