Foot Intertrigo Caused by Gram-Negative Bacteria

For a year, a 31-year-old man had asymptomatic, malodorous discoloration of the toe web spaces. He stated that his feet perspire heavily in the boots he is required to wear for work. Walter K. Nahm, MD, PhD, of San Diego and Anju Pabby, MD, and Richard Laws, MD, of Providence, RI, noted extensive maceration with a green tinge between all of the patient’s toes.

Results of a bacterial culture revealed Pseudomonas aeruginosa, Morganella morganii, and normal skin flora. The clinical presentation of foot intertrigo ranges from a chronic, macerated, desquamative dermatitis to an acute, painful, exudative, highly inflammatory process associated with cellulitis.¹ Foot intertrigo is caused most often by yeasts and dermatophytes² and less frequently by gram-negative bacteria.

P aeruginosa is the prevailing gram-negative pathogen, both alone and in association with other organisms, such as Escherichia coli, Proteus mirabilis, M morganii, and Enterobacter cloacae.^1,2 The blue-green pigment observed in P aeruginosa infections is caused by pyocyanin and fluorescein, which the bacteria produce. Depending on the severity of the infection, treatment may consist of topical medications or systemic antibiotics with gram-negative coverage.^1,3

However, antibiotic resistance can complicate the treatment of polymicrobial and especially P aeruginosa infections.³

In such cases, topical treatment with a diluted solution of sodium hypochlorite may be indicated. Because this patient had a superficial infection, treatment consisted of soaking the feet in a 1.5% sodium hypochlorite solution for 20 minutes per day for 7 days.

The green pigment and maceration resolved within a week. To prevent recurrence, this patient was instructed to keep the feet dry by using such measures as gauze pledgets between the toes, powder, astringent soaps, and open-toed shoes.