Botanical disruption of host-pathogen interactions and biofilm gene expression in uropathogenic Klebsiella pneumoniae

The increasing prevalence of biofilm-forming Klebsiella pneumoniae in urinary tract infections (UTIs) necessitates the exploration of alternative plant-based therapeutics. This study aimed to comparatively evaluate the anti-biofilm and virulence-attenuating properties of aqueous extracts from Mesembryanthemum nodiflorum (ice plant) and Maclura pomifera (Osage orange) against clinical K. pneumoniae isolates. Clinically confirmed K. pneumoniae isolates were screened for biofilm formation capacity. Following the preparation of both plant extracts, their minimum inhibitory concentrations (MICs) were determined. Furthermore, the sub-inhibitory impacts of these extracts on biofilm formation, bacterial adhesion, and invasion in the human epithelial cell model (HK-2) were evaluated. The transcriptional modulation of key virulence genes (fimH, mrkA, rmpA, wzi, luxS) was assessed using qRT-PCR. Cytotoxicity was evaluated via the MTT assay. Among the isolates, 80.9% exhibited biofilm-producing capabilities. The M. nodiflorum extract demonstrated a superior inhibitory profile (MIC = 256 µg/mL) compared to M. pomifera (MIC = 512 µg/mL). At sub-MIC levels, M. nodiflorum significantly reduced biofilm biomass by 41.7%, whereas M. pomifera achieved only a 22.5% reduction. Similarly, host cell adhesion and intracellular invasion were suppressed by approximately 45% using M. nodiflorum, compared to a marginal 20–24% reduction by M. pomifera. Transcriptional profiling confirmed that M. nodiflorum strongly downregulated fimH, mrkA, rmpA, wzi, and luxS expression, while the regulatory impact of M. pomifera was notably weaker. Both extracts maintained high host cell viability (>89%) at therapeutic doses. The M. nodiflorum aqueous extract exhibits significantly higher translational potential than M. pomifera as an anti-virulence agent. By effectively disrupting the biofilm genetic architecture and limiting host-pathogen interactions, M. nodiflorum offers a promising scaffold for managing K. pneumoniae-associated UTIs.