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Use of cefazolin microspheres to treat localized methicillin-resistant Staphylococcus aureus infections in rats
M T Fallon1, W Shafer, E Jacob
1Atlanta VA Medical Center Research Service, Emory University, Atlanta, Georgia, USA.
Background:
In a previous study, the topical administration of biodegradable, controlled-release poly-(dl-lactide-co-glycolide) cefazolin microspheres could effectively prevent surgical wound infections with a sensitive strain of Staphylococcus aureus in an experimental animal model. The objective of the current study was to evaluate and compare the efficacy of topical antibiotic therapy with cefazolin microspheres to systemic cefazolin therapy for the treatment of experimental rat surgical wounds contaminated with a methicillin-resistant strain of S. aureus (MRSA).
Methods:
A local infection model in rats was used. MRSA was used to infect pockets surgically produced in the paraspinous muscles. Groups of rats received either topical cefazolin microspheres, topical cefazolin powder, parenteral cefazolin, or no treatment. Feces were cultured to evaluate the effect of antibiotic therapy on gut flora.
Results:
The rate of clinical wound infection following topical application of cefazolin microspheres (13%) was significantly lower than the 53% infection rate observed in rats who had received a 2-week course of systemic cefazolin therapy (P = 0.046). Moreover, single-dose topical antibiotic therapy with cefazolin microspheres completely eradicated MRSA from the wounds of 7 of 15 (47%) animals. There was no statistically significant difference, however, in the rate of clinical wound infection between rats whose wounds were treated topically with free cefazolin powder and those treated with systemic cefazolin (P = 0.12). Importantly, selection of antibiotic-resistant bacteria was associated with systemic but not local cefazolin therapy.
Conclusion:
The results of this study suggest that topical antibiotic therapy with controlled-release cefazolin microspheres may be effective for the prevention of wound infection with both methicillin-sensitive and methicillin-resistant strains of S. aureus in selected surgical procedures that are at high risk of developing postoperative wound infection.
Insights
Topical cefazolin microspheres significantly reduced surgical wound infections from methicillin-resistant Staphylococcus aureus (MRSA) in rats compared to systemic therapy. This localized treatment also prevented the development of antibiotic resistance, offering a promising approach for high-risk surgical procedures.
Area of Science:
- Surgical infection prevention
- Antibiotic delivery systems
- Pharmacology
Background:
- Previous studies demonstrated poly-(dl-lactide-co-glycolide) cefazolin microspheres' efficacy against sensitive Staphylococcus aureus.
- Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant challenge in surgical wound infections.
Purpose of the Study:
- To compare the efficacy of topical cefazolin microspheres versus systemic cefazolin for treating MRSA-contaminated experimental rat surgical wounds.
- To evaluate the impact of topical and systemic cefazolin therapy on gut flora and antibiotic resistance.
Main Methods:
- A rat model of local surgical wound infection using MRSA.
- Administration of topical cefazolin microspheres, topical cefazolin powder, or parenteral cefazolin.
- Monitoring of clinical wound infection rates and fecal cultures to assess gut flora and resistance.
Main Results:
- Topical cefazolin microspheres resulted in a significantly lower infection rate (13%) compared to systemic cefazolin (53%).
- Single-dose topical microspheres eradicated MRSA in 47% of animals.
- Systemic cefazolin therapy, but not local therapy, was associated with the selection of antibiotic-resistant bacteria.
Conclusions:
- Topical controlled-release cefazolin microspheres show potential for preventing wound infections caused by both methicillin-sensitive and MRSA.
- This localized antibiotic approach may be beneficial for high-risk surgical procedures.
- The study highlights the advantage of topical delivery in mitigating antibiotic resistance development.