Lipid Nanoparticles Enhance the Antichlamydial Efficacy of Ciprofloxacin and Sulfamethoxazole–Trimethoprim

Background/Objectives:Chlamydia trachomatis (C. trachomatis) infections represent a major global public health concern, with over 100 million new cases annually. Although commonly used antibiotics like azithromycin and doxycycline are generally effective, increasing antibiotic resistance and therapeutic failures highlight the need for alternative treatments and innovative delivery systems. Methods: The efficacy of alternative antimicrobial agents, including ciprofloxacin and the combination of sulfamethoxazole and trimethoprim, was evaluated in both free and nano-formulated states. Drug encapsulation was achieved using liposomes as well as niosomal and aspasomal delivery systems. In vitro experiments were conducted on HeLa cells infected with C. trachomatis serovar D. Host cell viability and cytotoxicity were assessed using the MTT assay, while bacterial genomic load was quantified by qPCR. Results: Encapsulation significantly enhanced antimicrobial activity, with certain antibiotic-loaded lipid nanoparticles demonstrating 2–4 times greater effectiveness compared to their free counterparts. The prepared formulations exhibited no cytotoxic effects and did not interfere with PCR-based detection, confirming that observed outcomes reflect true antimicrobial activity. Conclusions: Nanocarrier-based drug delivery, particularly using lipid nanoparticles, represents a promising strategy for improving the therapeutic management of C. trachomatis infections. These findings highlight the potential of delivery platforms to enhance antibiotic performance and support the development of more effective and innovative antimicrobial therapies.