Leveraging collateral sensitivity to counteract the evolution of bacteriophage resistance in bacteria
image: (A) Evolutionary trajectory of Kp067 examined under sequential exposure to each of the three phages. Visible plaque represents phage sensitivity, while no plaque represents phage resistance. The orange-colored phages represent the Podoviruses phage ΦRCIP0041, while the green-colored ones represent the Myoviridae phage ΦRCIP0002, and the purple-colored ones represent the Siphoviridae phage ΦRCIP0070. R, resistance to phage; S, sensitivity to phage. (B) Schematic representation of IS5 insertion sites in Kp067 phage-resistant mutants. The arrows in colors of blue, tawny, and green, respectively, represent the wcaJ, gmhB, and wbbY, the corresponding genes inserted by IS5, while the red arrows represent IS5. The numbers under the genes represent the coding regions on the chromosome of Kp067 for these three genes: wcaJ, 1773485..1774888; gmhB, 4327107..4327673; and wbbY, 4713063..4715285. The numbers above these genes donate the insertion site of the IS5 element for each gene, for example, 1282; the IS5 inserted into the 1282th bp of the wcaJ gene.
Credit: Jie Feng, Institute of Microbiology, Chinese Academy of Sciences
Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKp), exhibiting multidrug resistance, can rapidly spread in both hospital and community settings, increasing the risk of infection outbreaks and posing a significant public health threat. Consequently, novel therapeutic approaches are urgently needed. Phage therapy, leveraging its unique bactericidal mechanism, high specificity, and evolutionary adaptability, is regarded as one of the most promising alternative strategies against drug-resistant bacterial infections.
Resistance evolution experiments revealed that resistance to the phage cocktail stemmed from dynamic alterations in bacterial surface receptors. When strain Kp067 developed resistance to phage ΦRCIP0041 (wcaJ gene insertion), its susceptibility to phages ΦRCIP0002 and ΦRCIP0070 increased. Subsequently, the ΦRCIP0002-resistant mutant (gmhB insertion) remained susceptible to ΦRCIP0070, while the final ΦRCIP0070-resistant mutant (wbbY insertion) regained susceptibility to ΦRCIP0002. This collateral sensitivity phenomenon was directly linked to sequential IS5 transposon insertions into the wcaJ (CPS synthesis), gmhB (LPS core synthesis), and wbbY (O1 antigen synthesis) genes. This reveals inherent defensive vulnerabilities arising when bacteria modify distinct surface receptors (CPS, LPS core, O1 antigen) to counter phage pressure. To further evaluate the therapeutic potential of the phage cocktail against Kp067 infection, the research team established an acute CR-hvKp infection model. Experiments showed that infection with Kp067 resulted in a 67% mortality rate in mice, whereas the phage cocktail achieved 100% survival with only minimal changes in body weight percentage. These results demonstrate that the phage cocktail significantly mitigated CR-hvKp infection in mice.
This study elucidates the molecular mechanism of phage-mediated collateral sensitivity, systematically reveals the interaction mechanisms between K. pneumoniae's major surface receptors and phages, provides novel insights for suppressing phage resistance, and demonstrates the efficacy of a collateral sensitivity-based phage combination in eliminating infection in vivo, highlighting its clinical therapeutic potential. Future efforts should fully exploit phage collateral sensitivity to develop potent phage cocktails for combating multidrug-resistant bacterial infections.
How to cite this article: Mu Y, Song Y, Tian X, Ding Z, Yao S, Li Y, et al. Leveraging collateral sensitivity to counteract the evolution of bacteriophage resistance in bacteria. mLife.2025;4:143–154.