Diagnosis of dermatophytes: from microscopy to direct PCR

Abstract

Dermatophyte fungi are a common cause of skin, nail and hair infections globally, ranging from mild to cosmetically disfiguring, or even invasive infections in rare cases. Specimens requiring fungal microscopy and culture for suspected dermatophyte infection make up a significant portion of the workload in diagnostic microbiology laboratories. Whilst still considered the gold standard, a dermatophyte culture-based method is labour intensive, has poor sensitivity, slow result turnaround time and requires significant expertise for identification of the fungi. Molecular diagnostics, especially real-time PCR, have the potential to improve diagnostic sensitivity, reduce labour requirements and decrease result turnaround times. Despite these advantages, a PCR-based approach may present some difficulties and disadvantages, most notably its diagnostic range and incompatibility with oral therapy prescribing requirements under the Pharmaceutical Benefits Scheme. Here we review current best practices and future prospects for laboratory diagnosis of dermatophyte infections, including the role of microscopy, culture and direct PCR.