Use of a commercial qPCR assay in 52 high risk shelter cats for disease identification of dermatophytosis and mycological cure

Background qPCR is used to test for dermatophytosis. Objectives To determine the clinical usefulness of a commercial qPCR for confirming dermatophytosis in lesional cats, and the clinical usefulness of the qPCR Microsporum spp. and/or M. canis assay for confirming mycological cure. Animals Fifty two shelter cats with skin lesions. Methods qPCR testing of toothbrush fungal culture samples of lesions. Results qPCR and fungal culture (FC) matched in 49 of 52 cats. The qPCR correctly identified 45 of 46 and two of four cats with M. canis and Trichophyton spp. infections, respectively. qPCR correctly identified two cats as not infected. No evidence of cross reactivity was noted. The Microsporum spp. qPCR assay was positive in 45 of 46 (97.8%) of infected cats. Results were positive on both Microsporum spp. and M. canis assays in 29 of 45 cats. No cat had a positive qPCR result for M. canis alone. Mycological cure was defined as two negative fungal cultures. There were 92 negative FC from the 46 treated cats and qPCR assay for Microsporum spp. and M. canis was negative in 68 of 92 (73.1%) and 79 of 92 (85.9%) samples, respectively. The number of cats correctly identified with mycological cure via qPCR was 30 of 46 (65.2%) and 39 of 46 (84.8%) cats for the Microsporum spp. and M. canis assays, respectively. Conclusions and clinical importance The commercial qPCR assay was a reliable test for confirming disease. The qPCR Microsporum spp. assay was more useful for initial disease confirmation; while the qPCR M. canis assay was more useful for determining mycological cure.