ICAAC: Foot Fungi Spreads Person-to-Person at Home

October 6, 2006

SAN FRANCISCO -- The long-suspected spread of onychomycosis and other dermatophytic fungal infections among family members has been confirmed, researchers reported here.

SAN FRANCISCO, Oct. 6 -- The long-suspected spread of onychomycosis and other dermatophytic fungal infections among family members has been confirmed, researchers reported here.

Genetically matched dermatophytes were identified in members of 10 families, indicating onychomycosis or tinea pedis transmission from one person to the other, reported Mahmoud Ghannoum, Ph.D., of University Hospitals of Cleveland, and colleagues, at the Interscience Conference on Antimicrobial Agents and Chemotherapy.

He and colleagues conducted a prospective, multicenter study that included 57 families with at least one member diagnosed with tinea pedis or onychomycosis, or both, using clinical signs and mycological culture.

After identifying an index patient, the investigators examined individuals in the same family for the infection. Dermatophyte strains were tested with polymerase chain reaction (PCR) and Southern blot analysis. Those patients treated with over-the-counter agents or home remedies within four weeks of the study and those who received prescription oral, or topical antifungal agents within four months were excluded.

In the study, transmission of identical strains of dermatophytes was found in 10 of 19 families (53%) that had more than one member with nail fungus or athlete's foot.

Among these families nearly all had T. rubrum (87.5%) rather than the other two common dermatophytes, T. mentagrophytes or Epidermophyton floccosum. T. rubrum was 5.79 times more likely to cause spread of infection than the other types.

While T. rubrum was significantly associated with spread (P=0.023), the most significant factor was presence of the strain type B or D (OR 9.00, P

Common precautions against athlete's foot and nail fungus include making sure feet stay dry, wearing high cotton content socks and appropriate shoes, Dr. Ullmann said.

The study was funded by Novartis Pharmaceuticals, which makes Lamisil. (terbinafine). A co-author is a Novartis employee.