Phenotypic heterogeneity and genetic mechanisms of phage resistance in hypervirulent carbapenem-resistant Klebsiella pneumoniae.

Four distinct phenotypes of phage resistance, including complete and partial resistance, were identified in hypervirulent carbapenem-resistant Klebsiella pneumoniae under phage Kpph1 pressure.

• Why it matters: Understanding the phenotypic heterogeneity and genetic mechanisms of phage resistance is essential for improving phage therapy against multidrug-resistant bacteria, yet these mechanisms remain incompletely characterized.
• What they did: Researchers examined resistant strains, revealing diverse resistance strategies such as receptor masking, growth inhibition, and community resistance, with wcaJ mutations as the main mechanism identified through genetic analysis.
• The result: A phage cocktail combining Kpph1 and a secondary phage K2V3 effectively suppressed all resistant variants, preventing further resistance and providing a foundation for optimizing clinical phage therapy.