Mupirocin is used topically as a dermatologic ointment for the treatment of impetigo caused by Staphylococcus aureus and Streptococcus pyogenes (group A β-hemolytic streptococci). Topical mupirocin is considered a drug of choice for treatment of impetigo, especially when limited numbers of lesions are present. If impetigo is extensive or has not responded to topical anti-infectives, an oral anti-infective active against S. aureus and S. pyogenes (e.g., dicloxacillin, cephalosporins, erythromycin, clindamycin, fixed combination of amoxicillin and clavulanate) should be used.
Mupirocin calcium is used topically as a dermatologic cream for the treatment of secondarily infected traumatic skin lesions (e.g., lacerations, sutured wounds, abrasions) that are not more than 10 cm in length or 100 cm in total area and are caused by susceptible S. aureus and S. pyogenes.
Topical mupirocin also has been effective when used in the treatment of other primary or secondary superficial skin infections, including ecthyma, eczema, folliculitis, furunculosis, atopic dermatitis, epidermolysis bullosa, and minor wounds, burns, and ulcers caused by susceptible bacteria.
Some clinicians suggest that topical mupirocin may be preferred over systemic anti-infective therapy for the treatment of impetigo and other superficial skin infections caused by susceptible bacteria since the drug appears to be as effective as and is associated with fewer adverse effects than systemic therapy. However, systemic anti-infectives generally are necessary for the treatment of serious or extensive skin infections.
In placebo-controlled studies in patients with primary or secondary bacterial skin infections, including impetigo, topical mupirocin ointment (in a polyethylene glycol [PEG] vehicle) resulted in a bacteriologic cure in 80-94% and clinical cure or improvement in 71-100% of patients; the PEG vehicle alone (which also has some antibacterial activity at high concentrations) resulted in a bacteriologic cure in 33-62% and clinical cure or improvement in 35-85% of patients. In one study in adult and pediatric patients with impetigo randomized to receive topical mupirocin 2% ointment for dermatologic use or topical vehicle placebo 3 times daily for 8-12 days, the bacteriologic cure rate and clinical efficacy rate in evaluable patients were 94 and 71%, respectively, in those treated with mupirocin compared with 62 and 35%, respectively, in those treated with the vehicle placebo. In evaluable pediatric patients 2 months to 15 years of age in this study, the clinical efficacy rate was 78% in those who received mupirocin ointment and 36% in those who received vehicle placebo.
In a randomized study in adult and pediatric patients with impetigo who were treated with topical mupirocin 2% ointment for dermatologic use 3 times daily for 7 days, the clinical efficacy rate (1 week after treatment) in evaluable patients was 95% in those who received mupirocin ointment formulated in a PEG vehicle (Bactroban) and 94% in those who received mupirocin ointment formulated in a vehicle without PEG (Centany); the pathogen eradication rate was the same (98%) in both groups. The clinical efficacy rate in evaluable pediatric patients 2 months to 15 years of age in this study was 95% in those who received Bactroban and 93% in those who received Centany.
The comparative efficacy of topical mupirocin and oral anti-infectives in the treatment of superficial skin infections has been evaluated. Although most studies were not blinded and some were poorly controlled in terms of the severity of infection, topical mupirocin appears to be at least as effective as oral erythromycin, cloxacillin (not commercially available in the US), dicloxacillin, or cephalexin in the treatment of impetigo and other superficial skin infections. In one unblinded study in adult and pediatric patients with impetigo randomized to receive topical mupirocin 2% ointment for dermatologic use (in a PEG vehicle) 3 times daily or oral erythromycin (30-40 mg/kg daily) for 8 days, the bacterial eradication rate was 100% in both groups and the clinical efficacy rate (1 week after treatment) was 93% in those treated with topical mupirocin compared with 78.5% in those treated with oral erythromycin. In several studies in patients with both primary and secondary superficial skin infections, topical mupirocin resulted in a bacteriologic cure in 91-100% of patients and clinical cure or improvement in 94-100% of patients, and oral erythromycin or cloxacillin resulted in bacteriologic cure in 50-91% of patients and clinical cure or improvement in 73-100% of patients. In 2 randomized, double-blind, multicenter clinical studies in adults and children with secondarily infected traumatic skin lesions, including lacerations, sutured wounds, and abrasions, topical mupirocin cream (applied 3 times daily for 10 days) or oral cephalexin (250 mg administered 4 times daily for 10 days) produced clinical efficacy rates of about 96 or 93-97%, respectively; the bacterial cure rate was 100% in both groups.
There is some evidence that topical mupirocin and topical fusidic acid (not commercially available in the US) are equally effective for the treatment of impetigo and may be more effective than other topical anti-infectives that have been used for the treatment of impetigo and other superficial skin infections (e.g., bacitracin, gentamicin, neomycin, chlortetracycline [not commercially available in the US], fixed-combination preparation containing bacitracin, neomycin, and polymyxin B sulfate).
Nasal Carriage of Staphylococcus aureus
Mupirocin calcium is used intranasally to temporarily eliminate nasal carriage of methicillin-resistant S. aureus (MRSA; also known as oxacillin-resistant S. aureus or ORSA). The drug also has been used intranasally to temporarily eliminate nasal carriage of methicillin-susceptible S. aureus.
Mupirocin calcium ointment for intranasal use (Bactroban Nasal) is labeled by the US Food and Drug Administration (FDA) for elimination of nasal carriage of MRSA in adult patients and health-care workers as part of a comprehensive infection control program to reduce the risk of infection among patients at high risk of MRSA infection during institutional outbreaks of infections caused by this pathogen. The manufacturer states that data are insufficient to date to establish whether the intranasal ointment is safe and effective when used as part of an intervention program to prevent autoinfection of high-risk patients from their own nasal colonization with S. aureus and that data are insufficient to date to recommend use of the ointment for general prophylaxis of any infection in any patient population.
Because nasal carriage of S. aureus is considered a risk factor for subsequent staphylococcal infections, intranasal mupirocin has been used to eliminate nasal carriage of S. aureus in carriers at high-risk of staphylococcal infections (e.g., surgical patients, cancer patients, hemodialysis patients) in an attempt to decrease the incidence of infections in these patients. It has been suggested that data are insufficient to support routine use of topical and/or systemic anti-infectives for eradication of MRSA colonization. However, some experts suggest that eradication of nasal carriage of S. aureus may be a reasonable strategy in certain patients with multiple documented recurrences of MRSA infection. In addition, there is some evidence from controlled studies in high-risk patients that use of intranasal mupirocin in S. aureus carriers can reduce the overall S. aureus infection rate in such individuals. Therefore, some experts suggest that intranasal mupirocin may be considered for hospitalized surgical, dialysis, and nonsurgical patients at risk of infection if they are known nasal carriers of S. aureus.
Permanent eradication of nasal carriage of S. aureus following topical or systemic anti-infective therapy is unlikely; recolonization generally occurs in 30-100% of patients regardless of the anti-infective agent used. Studies using intranasal mupirocin indicate that nasal carriage of S. aureus usually is eliminated within the first 1-4 days of therapy, but recolonization usually occurs 2-17 days or up to several weeks or months later until the drug is discontinued.