A comparison of the prophylactic uses of topical mupirocin and nitrofurazone in murine crush contaminated wounds

Objectives

This work was conducted to study the prophylactic efficacy of 2 topical antibiotic ointments (mupirocin and nitrofurazone) against wound infection in experimental contaminated crush wounds.

Methods

Male Wistar rats underwent two 2-cm incisions at the back side and randomized into 3 groups—placebo (n = 14), mupirocin (n = 14), and nitrofurazone (n = 14)—and infected with either Staphylococcus aureus or S pyogenes. All wound edges were crushed for 5 seconds with hemostats to simulate crush injury before inoculation of the microorganisms. Half of the wounds were sutured and the other half left open. These wounds were treated 3 times daily for 6 days with topical mupirocin, nitrofurazone, or petrolatum (as placebo). At the end of 6 days, excisional biopsies were taken from wound edges and histopathologic assessments were made based on neutrophilic infiltration, edema formation, myofibroblastic proliferation, and granulation tissue formation. For the microbiologic assessments, quantitative tissue cultures were made.

Results

In S aureus-inoculated wounds, mupirocin showed higher antibacterial activity against bacterial colonization and reduced infection rates compared to placebo groups. The same effect was observed for the infection rates in S pyogenes-inoculated wounds. In S pyogenes-inoculated open wounds, nitrofurazone showed higher antibacterial activity against infection, but this effect was not observed in closed wounds. In S pyogenes- and S aureus-infected wounds, mupirocin treatment significantly lowered infection rates compared to nitrofurazone treatment. Histopathologic examination showed higher myofibroblastic proliferation and higher volume of granulation tissue in the nitrofurazon groups compared to the mupirocin groups.

Conclusion

Topical mupirocin application was effective against crush wound infections inoculated with S pyogenes and S aureus. Nitrofurazone provides better granulation tissue formation, but did not effectively prevent bacterial colonization and infection in crush contaminated wounds.