Development and validation of a real-time multiplex PCR assay for the detection of dermatophytes and Fusarium spp.

Introduction: Onychomycosis is a debilitating, difficult-to-treat nail fungal infection with increasing prevalence worldwide. The main etiological agents are dermatophytes, which are common causative pathogens in superficial fungal mycoses. Conventional detection methods such as fungal culture have low sensitivity and specificity and are time-consuming.Aim: The main objective of this study was to design, develop and validate a real-time probe-based multiplex qPCR assay for the detection of dermatophytes and Fusarium species.Methodology: The performance characteristics of the qPCR assays were evaluated. The multiplex qPCR assays targeted four genes (assay 1: pan-dermatophytes/Fusarium spp.; assay 2: Trichophyton rubrum/Microsporum spp.). Analytical validation was accomplished using 150 fungal isolates and clinical validation was done on 204 nail specimens. The performance parameters were compared against the gold standard (fungal culture) and expanded gold standard (culture in conjunction with sequencing).Results: Both the single-plex and multiplex qPCR assays performed well especially when compared against the expanded gold standard. Among the 204 tested nail specimens, the culture method showed that 125 (61.3 %) were infected with at least one organism, of which 40 yielded positive results for dermatophytes and Fusarium spp. These target organisms detected include 20 dermatophytes and 22 Fusarium spp. The developed qPCR assays demonstrated excellent limit of detection, efficiency, coefficient of determination, analytical and clinical sensitivity and specificity.Conclusion: The multiplex qPCR assays were reliable for the diagnosis of onychomycosis, with shorter turn-around time as compared to culture method. This aids in the planning of treatment strategies to achieve optimal therapeutic outcome.

Cutaneous pseudolymphoma occurring after traumatic implantation of a foreign red pigment.

Cutaneous pseudolymphoma is an uncommon, benign lymphoproliferative disorder of the skin. Although this condition is most commonly idiopathic, its occurrence has been associated with cosmetic tattoos. We report a unique case of cutaneous pseudolymphoma that occured after accidental, traumatic inoculation of a red pigment in a healthy 33-year-old woman.

Pityriasis lichenoides in an Asian population.

BACKGROUND: There are few studies comparing pityriasis lichenoides (PL) in adults and children, with fewer involving Asians. We compared the clinical profile and treatment outcomes of 10 adults and five children diagnosed with PL. METHODS: We retrospectively reviewed a series of patients diagnosed with PL at our hospital from 2002 to 2008. RESULTS: We identified 10 adults and five children (nine adults and four children with pityriasis lichenoides chronica; one adult and one child with pityriasis lichenoides et varioliformis acuta). Mean age of onset of disease was 42.2 years in adults and 12.2 years in children. Median duration of disease before presentation was 5.5 months in adults and 6 months in children. Trunk and limbs were the most common sites of involvement. Itch was present in the majority. Almost all patients did not respond to topical corticosteroids. A good response was seen in three adults and two children treated with oral antibiotics. Three adults and two children responded to treatment with narrow-band ultraviolet B phototherapy. The median time to resolution was 8 months in adults and 21 months in children. Postinflammatory dyspigmentation was seen in six adults and four children. CONCLUSION: PL presents similarly in adults and children; however, it runs a longer course in children. In our series, postinflammatory hyperpigmentation was common, which may be explained by our patients' darker skin phototypes. We routinely prescribe oral antibiotics initially in patients without contraindications. Phototherapy may be useful in patients not responding to antibiotics.