S1 Guideline on Infected Interdigital Intertrigo (also called Gram-Negative Toe Web Infection)

Infected interdigital intertrigo is an exudative, macerating, mixed infection of the toe webs in which gram-negative bacteria (Pseudomonas aeruginosa and Enterobacterales) seem prevalent, but in which gram-positive pathogens (Staphylococcus [S.] aureus, streptococci, enterococci) and fungi (dermatophytes, yeasts) also occur. The former German term "gram-negative foot infection" misleadingly implied a soft-tissue infection of the foot caused by gram-negative bacteria. The updated term "infected interdigital intertrigo" is an internationally used designation, as is the term "gram-negative toe web infection". This superficial infection may yet progress to soft tissue infection (phlegmon, cellulitis) of the foot but in immunocompetent patients is usually caused by S. aureus. Complicated courses, as well as the development of interdigital intertrigo itself, are facilitated by diabetes mellitus, polyneuropathy, and peripheral arterial disease. Diagnosis is made clinically, based on painful macerated erosions or ulcers with yellow-green exudate, putrid odor and edema. Superficial swabs are not always diagnostically required or relevant. Management focuses on local therapy with anti-inflammatory, antiseptic, antimycotic agents, dry wound care and reduction of edema. Systemic antibiotics are indicated only in cases of associated soft-tissue infection, which in immunocompetent patients present as uncomplicated cellulitis and therefore require coverage limited to S. aureus. Early vascular evaluation, imaging and surgical assessment in cases of deep infection or necrosis are essential.