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Topical antibiotic treatment of impetigo with mupirocin
Abstract:
Because the effectiveness of topical antimicrobials in the treatment of ecthyma, impetigo, and pyoderma is not well established, the US Food and Drug Administration has recently proposed guidelines for tests of topical antimicrobial efficacy in primary skin infections. The guidelines require both comparison with the agent's base and microbiologic documentation of efficacy. These guidelines were followed in this double-blind, eight-day evaluation of impetigo/ecthyma treated with mupirocin, a new agent that is only active topically. All cultures, before and after therapy, were taken using swabs dipped in neutralizing broth plus 10% fetal bovine serum to minimize antimicrobial "carry over" to the culture plate. Staphylococcus aureus, which was isolated from 94% of the patients before therapy, was eliminated in 88% of the mupirocin-treated patients and 47% of the vehicle-treated patients. Group A beta-hemolytic streptococci were eliminated in 100% of the mupirocin-treated and 0% of the vehicle-treated patients. To our knowledge, this is the first topical antibacterial treatment for primary skin infections proved superior to its vehicle using the proposed US Food and Drug Administration guidelines.
Insights
Mupirocin effectively treated impetigo and ecthyma by eliminating bacteria like Staphylococcus aureus. This study followed new US Food and Drug Administration guidelines for topical antimicrobial efficacy testing.
Area of Science:
- Dermatology
- Infectious Diseases
- Microbiology
Background:
- The efficacy of topical antimicrobials for primary skin infections like ecthyma, impetigo, and pyoderma is not well-established.
- The US Food and Drug Administration (FDA) proposed new guidelines for testing topical antimicrobial efficacy, requiring comparison with a vehicle control and microbiological proof of effectiveness.
Purpose of the Study:
- To evaluate the efficacy of mupirocin, a novel topical antimicrobial, in treating impetigo and ecthyma.
- To adhere to the recently proposed FDA guidelines for testing topical antimicrobial agents.
Main Methods:
- A double-blind, eight-day clinical trial was conducted.
- Patients with impetigo/ecthyma were treated with either mupirocin or its vehicle.
- Microbiological cultures were obtained before and after therapy using a neutralizing broth method to prevent antimicrobial carry-over.
Main Results:
- Mupirocin demonstrated superior efficacy compared to the vehicle control.
- Staphylococcus aureus was eradicated in 88% of mupirocin-treated patients versus 47% of vehicle-treated patients.
- Group A beta-hemolytic streptococci were eradicated in 100% of mupirocin-treated patients compared to 0% of vehicle-treated patients.
Conclusions:
- Mupirocin is an effective topical treatment for impetigo and ecthyma.
- This study provides the first evidence of a topical antibacterial agent proving superior to its vehicle under the proposed FDA guidelines for primary skin infections.