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Klebsiella pneumoniae (KP) has emerged as a formidable nosocomial pathogen in the era of antimicrobial resistance, with mortality from pneumonia caused by carbapenem-resistant strains exceeding 50%. Phage therapy has re-emerged as a promising alternative or adjunctive strategy for managing refractory KP infections. This review consolidates the current preclinical and clinical evidence base, outlines the molecular mechanisms of phage-host interactions, and appraises evolving therapeutic approaches. Preclinical investigations in murine pneumonia models have consistently demonstrated that intranasal or nebulization phage administration markedly reduces pulmonary bacterial burden, attenuates inflammatory lung injury, and improves survival, often exhibiting synergistic effects when combined with conventional antibiotics. Clinical case reports and small compassionate-use series have further provided preliminary yet compelling evidence supporting the safety and therapeutic promise of personalized phage formulations in critically ill patients with multidrug-resistant KP pneumonia who have exhausted standard treatment options. Mechanistically, phage tropism is mediated through the specific recognition of bacterial surface receptors-principally capsular polysaccharide and, to a lesser extent, lipopolysaccharide-by phage-encoded receptor-binding proteins, culminating in bacterial lysis. In response, KP has evolved a multilayered defensive arsenal encompassing receptor modification to impede adsorption, nucleic acid interference systems (e.g., CRISPR-Cas and restriction-modification), and abortive infection mechanisms that curtail phage propagation at the population level. To surmount the inherent limitations of narrow host range and the inevitable emergence of phage-resistant mutants, a suite of optimization strategies is under active refinement, including rationally designed phage cocktails, genetically engineered phages with extended tropism, artificial intelligence-assisted host-range prediction, and innovative delivery platforms such as hydrogel encapsulation to enhance pulmonary bioavailability. Despite ongoing challenges in mechanistic complexity, manufacturing standardization, and regulatory uncertainty, current initiatives- such as the establishment of geographically diverse phage libraries, real-time surveillance of phage resistance, and the development of phage-derived enzyme products-hold promise for establishing precision phage therapy as a viable and sustainable component of the antimicrobial stewardship armamentarium.