Cryptococcus neoformans is an invasive fungus that causes both acute and chronic infections, especially in immunocompromised patients. Owing to the increase in the prevalence of drug-resistant pathogenic fungi and the limitations of current treatment strategies, drug repositioning has become a feasible strategy to accelerate the development of new drugs. In this study, the minimum inhibitory concentration of vitamin D₃ (VD₃) against C. neoformans was found to be 0.4 mg/mL by broth microdilution assay. The antifungal activities of VD₃ were further verified by solid dilution assays and “time-kill” curves. The results showed that VD₃ reduced fungal cell adhesion and hydrophobicity and inhibited biofilm formation at various developmental stages, as confirmed by crystal violet staining and the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide assay. Fluorescence staining of cellular components and a stress susceptibility assay indicated that VD₃ compromised cell integrity. Reverse transcription quantitative PCR demonstrated that VD₃ treatment upregulated the expression of fungal genes related to cell wall synthesis (i.e., CDA3, CHS3, FKS1, and AGS1). Moreover, VD₃ enhanced cell membrane permeability and caused the accumulation of intracellular reactive oxygen species. Finally, VD₃ significantly reduced the tissue fungal burden and prolonged the survival of Galleria mellonella larvae infected with C. neoformans. These results showed that VD₃ could exert significant antifungal activities both in vitro and in vivo, demonstrating its potential application in the treatment of cryptococcal infections.

• Therapeutic Landscape Evolution: Current FDA-approved triple regimens feature sulbactam-durlobactam (SUL-DUR), the siderophore cephalosporin cefiderocol (FDC), and eravacycline. Zosurabalpin remains in Phase I evaluation, while Acinetobacter baumannii prophylactic vaccines are still undergoing preclinical development. • CRAB Treatment Paradigms: SUL-DUR combination therapy emerges as a promising first-line therapeutic candidate for critically ill patients with carbapenem-resistant Acinetobacter baumannii (CRAB) infections. FDC demonstrates pivotal potential in multidrug-resistant pathogen co-therapy frameworks through its innovative iron-transport mechanism. • Strategic Interventions: Dual-track approaches are imperative: 1) Accelerating CRAB-targeted drug development through priority review pathways, implementing adaptive clinical trial designs, and establishing dynamic risk management-based post-marketing surveillance systems; 2) Strengthening institutional infection control protocols and refining antimicrobial stewardship programs to curb CRAB dissemination.

Acinetobacter baumannii is a significant opportunistic pathogen causing severe nosocomial infections that poses increasing clinical challenges due to escal