Mupirocin Cream Is as Effective as Oral Cephalexin in the Treatment of Secondarily Infected Wounds

Journal of Family Practice, Dec, 1998 by Stephen J. Kraus, Lawrence J. Eron, Gerald W. Bottenfield, Margaret A. Drehobl, William D. Bushnell, Michael A. Cupo

BACKGROUND. Topical antimicrobials have been considered for treatment of secondarily infected wounds because of the potential for reduced risk of adverse effects and greater patient convenience. We compared mupirocin cream with oral cephalexin in the treatment of wounds such as small lacerations, abrasions, or sutured wounds.

METHODS. In 2 identical randomized double-blind studies, 706 patients with secondarily infected wounds (small lacerations, abrasions, or sutured wounds) received either mupirocin cream topically 3 times daily or cephalexin orally 4 times daily for 10 days.

RESULTS. Clinical success at follow-up was equivalent in the two groups: 95.1% and 95.3% in the mupirocin cream and the cephalexin groups, respectively (95% confidence interval [CI], -4.0% to 3.6%; P = .89). The intention-to-treat success rate was 83% in both groups. Bacteriologic success at follow-up was also comparable: 96.9% in the mupirocin cream and 98.9% in the cephalexin groups (95% CI, -6.0% to 2.0%; P = .22). The occurrence of adverse experiences related to study treatment was similar for the 2 groups, with fewer patients in the mupirocin cream group reporting diarrhea (1.1 % vs 2.3% for cephalexin).

CONCLUSIONS. Mupirocin cream applied topically 3 times daily is as effective as oral cephalexin given 4 times daily for the treatment of secondarily infected wounds and was well tolerated.

KEY WORDS. Mupirocin; cephalexin; wound infection; abrasion; laceration. (J Fam Pract 1998; 47:429-433)

Most patients with secondarily infected wounds are treated with systemic antimicrobials that pose a risk of adverse reactions, including hypersensitivity reactions and gastrointestinal disturbances. Topical antimicrobials may offer reduced risk of adverse effects and greater patient convenience. Mupirocin calcium cream is a new formulation of mupirocin that contains 20 mg mupirocin calcium in each gram of an emulsion base. It has antibacterial activity against the majority of common wound pathogens, including aerobic gram-positive cocci: Staphylococcus aureus (including methicillin-resistant strains), Staphylococcus epidermidis, Streptococcus pyogenes, and beta-hemolytic streptococci.[1] The cream formulation was developed because it is preferred over the ointment formulation for treatment of conditions when the lesion should be kept "dry." Also, polyethylene glycol in the ointment formulation poses a slight risk of nephrotoxicity if there is absorption through denuded epithelium. The ointment formulation of mupirocin was shown to be superior to ampicillin, erythromycin, and cloxacillin for treatment of primary and secondary skin infections.[2,3,4]

The objective of this study was to compare the efficacy, safety, and tolerability of the mupirocin calcium cream formulation with oral cephalexin in the treatment of patients with secondarily infected wounds (such as small lacerations, abrasions, or sutured wounds). This is the first report of this formulation for infected wounds.

METHODS

STUDY DESIGN

This report includes the combined results from 2 multicenter studies, with a total of 53 participating centers in the United States conducted concurrently under identical protocols between August 1994 and June 1996. Two studies were required for approval by the Food and Drug Administration. Treatment was randomized and administered in a double-blinded, double-dummy manner to 2 parallel groups. The protocol was approved by the investigational review board at each institution, and patients (or parent or legal guardian) provided written informed consent.

PATIENTS

Patients of any age presenting with secondarily infected wounds (such as a small laceration, abrasion, or sutured wound) who could be treated with mupirocin calcium cream or oral cephalexin were enrolled. Most patients were seen in physician offices or clinics. All patients had to have a Skin Infection Rating Scale (SIRS) total score of at least 8.[5] The SIRS score is a severity index based on a 0 (absent) to 6 (severe) scale, with a possible maximum score of 42. The parameters evaluated were: exudate/pus, crusting, erythema/inflammation, tissue warmth, tissue edema, itching, and pain. Investigators were instructed in the use of the scale, and it was applied by a single investigator at each site to assure continuity. Also, patients had to have a positive Wright stain for white blood cells from wound exudate. A laceration or sutured wound could not have exceeded 10 cm in length with surrounding erythema no more than 2 cm from the edge of the lesion. Abrasions could not exceed 100 [cm.sup.2] in total area with surrounding erythema no more than 2 cm from the edge of the abrasion.

Patients were excluded if they (1) demonstrated a previous hypersensitivity reaction to penicillins, cephalosporins, other beta-lactam antimicrobials, or mupirocin; (2) had a bacterial skin infection that, because of depth or severity, could not be appropriately treated with a topical antibiotic (eg, cellulitis, abscess, ulcer, furunculosis); (3) had a secondarily infected animal, human, or insect bite or a puncture wound; (4) had systemic signs or symptoms of infection; (5) required surgical intervention for treatment of the infection; (6) received a systemic antibacterial or steroid, or had applied any topical therapeutic agent directly to the wound or used soap containing an antibacterial agent within 24 hours before entering the study; (7) had a serious underlying disease as judged by the investigator; (8) were pregnant, breast-feeding, or planning a pregnancy during the study; (9) had used an investigational drug within 30 days before entering the study; or (10) had been previously enrolled in this protocol.