Potential Sexual Transmission of Antifungal-Resistant Trichophyton indotineae in the US

Click Here to View the Article

Situation summary:

  • Previous reports have described sexual transmission of genital dermatophytosis (common names: ringworm, tinea), but sexual transmission of Trichophyton indotineae, a frequently antimicrobial-resistant emerging fungus, had not been previously reported in the US.
  • A female patient in Pennsylvania was diagnosed with T indotineae infection on her genitals after travel in South Asia, where T indotineae infections are widespread.
  • The patient was immunocompetent and was likely infected through sexual contact.
  • The patient’s new partner in the US later became infected on his genitals, suggesting potential sexual transmission.
  • Before antifungal-resistant infection was recognized, the patient experienced substantial diagnostic and treatment delays and received multiple ineffective treatments, including corticosteroids that worsened her infection.
  • The fungus was resistant to and failed treatment with terbinafine (first-line antifungal), but the patient’s infection improved with itraconazole.

Clinical pearls:

  • T indotineae infections are often resistant to terbinafine, and itraconazole is considered first-line therapy for this pathogen.
  • T indotineaeis a potential cause of antifungal-resistant genital lesions. Clinical vigilance is needed to ensure prompt, effective antifungal treatment.
  • Visual inspection without diagnostic testing cannot reliably distinguish dermatophytosis from other causes of inflammatory skin conditions (eg, contact dermatitis).
  • Subsequent inappropriate use of corticosteroids can exacerbate dermatophytosis.
  • Diagnostic testing (eg, with potassium hydroxide preparation) is important to correctly diagnose and appropriately treat dermatophytosis and other fungal skin infections.

Public health implications:

  • Expand surveillance such as through sexual-health-provider networks to identify emerging trends in severe and antifungal-resistant dermatophytosis.
  • Conduct studies to understand T indotineae transmission dynamics.
  • Increase laboratory capacity to identify dermatophyte species and test for antifungal susceptibility.

 Actions for clinicians suspecting antifungal-resistant dermatophytosis:

Assistance for public health officials

Public health officials concerned about potential cases of antifungal-resistant dermatophytosis or unusual clusters of cases can email FungalOutbreaks@cdc.gov for assistance with recommendations and testing.