Laboratory Studies

To determine the etiologic agents, bacterial culturing and sensitivity testing, potassium hydroxide preparation, and fungal culturing should be performed. Some of the gram-negative organisms isolated and identified on Gram staining and/or culturing include P aeruginosa, Proteus mirabilis, and Enterococcus species. Usually, patients are infected by more than one organism. Some other organisms found on gram-negative cultures include Serratia marcescens, Escherichia coli, alpha streptococci, Proteus vulgaris, and Enterobacter species. Fungal culturing can be used to isolate a fungus associated with the infection, whether it is a dermatophyte or a yeast.

A patient's immune status may need to be evaluated, especially if response to therapy is slow, because serious potentially lethal systemic complications may occur. In addition, complete blood cell counts with differential and fasting blood glucose levels may be used to screen the patient's immune status and to exclude diabetes mellitus.

A Wood light examination and culture should be performed to establish the diagnosis of Pseudomonas toe web infection.

Histologic Findings

Histologically, an eroded epidermis is anticipated, sometimes with a serous or serosanguineous exudate at its base, with numerous neutrophils and scattered bacteria.

The infection can begin primarily as a typical tinea pedis infection, but it can escalate and become severe, manifesting erythema and erosions and extending beyond the toes.

Treatment & Management

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Media Gallery

A 33-year-old man with interweb exudative patches. Courtesy of Rajendra Kapila, MD, Professor of Infectious Diseases, New Jersey Medical School.

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Author

Robert A Schwartz, MD, MPH Professor and Head of Dermatology, Professor of Pathology, Professor of Pediatrics, Professor of Medicine, Rutgers New Jersey Medical School

Robert A Schwartz, MD, MPH is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, New York Academy of Medicine, Royal College of Physicians of Edinburgh, Sigma Xi, The Scientific Research Honor Society

Disclosure: Nothing to disclose.

Specialty Editor Board

David F Butler, MD Former Section Chief of Dermatology, Central Texas Veterans Healthcare System; Professor of Dermatology, Texas A&M University College of Medicine; Founding Chair, Department of Dermatology, Scott and White Clinic

David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, Association of Military Dermatologists, Phi Beta Kappa, Texas Dermatological Society

Disclosure: Nothing to disclose.

Rosalie Elenitsas, MD Herman Beerman Professor of Dermatology, University of Pennsylvania School of Medicine; Director, Penn Cutaneous Pathology Services, Department of Dermatology, University of Pennsylvania Health System

Rosalie Elenitsas, MD is a member of the following medical societies: American Academy of Dermatology, American Medical Association, American Society of Dermatopathology, Pennsylvania Academy of Dermatology

Disclosure: Received royalty from Lippincott Williams Wilkins for textbook editor.

Chief Editor

William D James, MD Paul R Gross Professor of Dermatology, Vice-Chairman, Residency Program Director, Department of Dermatology, University of Pennsylvania School of Medicine

William D James, MD is a member of the following medical societies: American Academy of Dermatology, Society for Investigative Dermatology

Disclosure: Received income in an amount equal to or greater than $250 from: Elsevier; WebMD<br/>Served as a speaker for various universities, dermatology societies, and dermatology departments.

Additional Contributors

Takeji Nishikawa, MD Emeritus Professor, Department of Dermatology, Keio University School of Medicine; Director, Samoncho Dermatology Clinic; Managing Director, The Waksman Foundation of Japan Inc

Disclosure: Nothing to disclose.

Acknowledgements

The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous authors, Dr. Frantisek Vosmik, and Jarrett R. Hesselbirg, MD, to the development and writing of this article.