Intra-discal vancomycin-loaded PLGA microsphere injection for MRSA discitis: an experimental study

Area of Science:

• Biomedical Engineering
• Drug Delivery Systems
• Infectious Diseases

Background:

• Infective discitis is a serious spinal infection often caused by Staphylococcus aureus.
• Current treatments for discitis, such as intravenous vancomycin, can have limitations in efficacy and require high dosages.
• Developing localized, sustained-release drug delivery systems can improve therapeutic outcomes and reduce systemic side effects.

Purpose of the Study:

• To prepare vancomycin hydrochloride (VA)-loaded poly lactic acid-glycolic acid (PLGA) copolymer microspheres using a multiple emulsion method.
• To evaluate the in vitro characteristics of VA-PLGA microspheres, including particle size, encapsulation efficiency, and drug release profile.
• To assess the therapeutic efficacy of intra-discal VA-PLGA microsphere injection for treating methicillin-resistant Staphylococcus aureus (MRSA) infective discitis in a rabbit model.

Main Methods:

• VA-PLGA microspheres were prepared via the multiple emulsion method.
• In vitro characterization included particle diameter distribution, shape, encapsulation efficiency, drug loading, and release kinetics.
• In vivo efficacy was evaluated in rabbits with MRSA-induced discitis, comparing intra-discal VA-PLGA injection to intravenous VA and blank PLGA microspheres, with assessments at 30 days via radiography, histology, and bacteriology.

Main Results:

• VA-PLGA microspheres exhibited mean particle diameters between 61.57 ± 4.37 and 67.45 ± 8.13 μm with encapsulation efficiencies ranging from 60.20 ± 1.61% to 75.27 ± 1.60%.
• In vitro release studies demonstrated drug release over 30 days.
• Intra-discal VA-PLGA injection resulted in significantly reduced inflammation and lower bacterial counts (1.02 × 10^3 ± 1.22 × 10^3 CFU/g) compared to intravenous VA (7.51 × 10^4 ± 7.16 × 10^4 CFU/g) (P < 0.05), using 1/120th of the vancomycin dose.

Conclusions:

• Intra-discal injection of VA-PLGA sustained-release microspheres is an effective and low-dosage treatment for infective discitis.
• This method demonstrates superior therapeutic effects compared to conventional intravenous vancomycin administration.
• Clinical trials are warranted to further validate these findings for human application.