OBJECTIVE: This study aimed to investigate the roles and mechanisms of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in the drug resistance of Klebsiella pneumoniae, focusing on its regulation of the aminoglycoside resistance methylase (armA) and the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway. METHODS: A549 cells were infected with drug-resistant Klebsiella pneumoniae and treated with meropenem. TRAIL overexpression and knockdown were performed using plasmids and small interfering RNA, respectively. Cell viability, apoptosis, and the levels of inflammatory cytokines including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β) were assessed. The mRNA expression of armA was examined using reverse transcription quantitative polymerase chain reaction (RT-qPCR). The expression of key proteins in the PI3K/AKT/mTOR pathway was evaluated using western blots. RESULTS: Drug-resistant Klebsiella pneumoniae infection reduced A549 cell viability, promoted apoptosis, and increased TNF-α, IL-6, and IL-1β levels. Meropenem treatment failed to reverse these effects, confirming the drug resistance. TRAIL overexpression exacerbated Klebsiella pneumoniae infection-induced viability inhibition, apoptosis, and inflammation, suggesting that TRAIL enhances the drug resistance of Klebsiella pneumoniae. In contrast, TRAIL knockdown showed the opposite results. TRAIL overexpression upregulated armA expression and activated the PI3K/AKT/mTOR pathway, but armA inhibition reversed TRAIL-mediated drug resistance and PI3K/AKT/mTOR activation. CONCLUSION: TRAIL-mediated armA upregulation enhanced the drug resistance of Klebsiella pneumoniae by activating the PI3K/AKT/mTOR signaling pathway. These findings provide new insight into the drug resistance mechanisms of Klebsiella pneumoniae.