Soaking socks in QAC-based detergent effectively reduces risk of reinfection in tinea pedis
Denmark: High rates of reinfection and the emergence of terbinafine-resistant strains of Trichophyton spp complicate the treatment of tinea pedis and onychomycosis. An important measure is the effective disinfection of contaminated socks. The risk of reinfection can be reduced by appropriate washing and is paramount for the treatment of tinea pedis and onychomycosis.
A recent study, published in the journal Mycoses, has found that soaking in a QAC-detergent for 24 h is effective in disinfecting sock pieces contaminated with dermatophytes.
The study was conducted by Ditte Marie Lindhardt Saunte, Department of Dermatology, Zealand University Hospital, Roskilde, Denmark, and colleagues with the objective to describe the effect of commonplace disinfection methods using socks pieces inoculated with terbinafine-resistant or terbinafine-susceptible isolates of Trichophyton spp.
For this purpose, sock pieces were inoculated with seven terbinafine-resistant isolates of Trichophyton spp. with known mutations in the SQLE-gene (T. rubrum (n = 3), T. interdigitale (n = 1) and T. indotineae (n = 3)) and six terbinafine-susceptible isolates of Trichophyton spp. (T. rubrum (n = 3) and T. interdigitale (n = 3)).
Disinfection methods included soaking in a quaternary ammonium (QAC) detergent (0.5, 2, and 24 h), freezing at −20°C (0.5, 12, and 24 h), domestic and steam washing (both at 40°C with detergent). Following disinfection, sock pieces were cultured for 4 weeks. No growth at the end of week 4 was the primary endpoint.
Key findings of the study are as follows:
- Soaking in a QAC-detergent for 24 h procured at disinfectant rate of 100%, whilst soaking in 0.5 and 2 h had a disinfectant rate of 46.2% and 84.6%, respectively.
- Domestic washing (40°C with detergent) produced a disinfectant rate of 7.7%.
- Freezing at −20°C (0.5, 12 and 24 h) and steam washing (40°C with detergent) had no disinfectant properties.
The researchers wrote in their conclusion, "patients should be advised to either launder their socks at a minimum of 60°C21, 22 or soak their socks in a QAC-based detergent for at least 24 h prior to laundering to effectively reduce the risk of reinfection."
The results of the study indicate that laundering at 40°C with domestic detergent, steam washing at 40°C with domestic detergent and freezing at −20°C all are not effective for disinfection of contaminated fabrics. The need for evidence-based recommendations is emphasized by high rate of reinfection from tinea pedis and onychomycosis.
"Considering the current epidemic of terbinafine-resistant infections, this has become even more important as effective disinfection of textiles may contribute to a lower reinfection and transmission rate," the authors wrote in their study.
Reference:
Skaastrup KN, Astvad KMT, Arendrup MC, Jemec GBE, Saunte DML. Disinfection trials with terbinafine-susceptible and terbinafine-resistant dermatophytes. Mycoses. 2022 Jul;65(7):741-746. doi: 10.1111/myc.13468. PMID: 35535729.
