Nanoparticle-based co-delivery of ciprofloxacin and meropenem enhances synergistic activity against multidrug-resistant hypervirulent Klebsiella pneumoniae clinical isolates.

Abstract

BACKGROUND: Despite the growing concern over MDR hypervirulent Klebsiella pneumoniae (MDR-hvKP), effective treatments remain limited. AIM: This study explores the potential of co-loading ciprofloxacin and meropenem into a nano-polymeric matrix to enhance their synergistic activity against MDR-hvKP and improve treatment outcomes in a hvKP-infected rat model. METHODS: Ten clinical K. pneumoniae isolates were tested for virulence genes (p-rmpA, iucA) to confirm the presence of hvKP. The synergistic activity of free-ciprofloxacin/meropenem and nanosized ciprofloxacin/meropenem was evaluated using checkerboard and time-kill assays. Survival rates and bacterial burden were assessed in a rat sepsis model after receiving either nano- or free-ciprofloxacin/meropenem. RESULTS: HvKP strains exhibited significantly lower MICs for nanosized drugs compared with free drugs. MICs of nano-ciprofloxacin ranged from 2 to 32 mg/L, and nano-meropenem from 0.125 to 64 mg/L, reflecting 2-4- and 4-16-fold reductions compared with free drugs. Nano- ciprofloxacin/meropenem combination displayed synergistic activity against 7 out of 10 hvKP strains and additive activity against three strains. By contrast, free-ciprofloxacin/meropenem showed synergy in only two strains, additive effects in two strains and indifferent activity in six strains. Time-kill assays demonstrated that monotherapies failed to inhibit bacterial growth, while nanosized combination exhibited bactericidal activity at 1×MIC. Nano-ciprofloxacin/meropenem significantly improved survival and reduced bacterial load compared with free drugs combination (P ≤ 0.0001). CONCLUSION: Dual antibiotic-loaded nanoparticles represent an innovative therapeutic approach against hvKP infections and highlight nanotechnology's potential in overcoming MDR pathogens for future clinical application.