P‐10 Comparison of carpet and toothbrush methods for the detection of asymptomatic carriage of dermatophytes in cats

Abstract

Diagnosis of Microsporum canis infection is a challenge in cats with suspected asymptomatic carriage. The aim of this study was to compare the carpet method and the toothbrush method of sample collection for dermatophyte culture. The study was conducted on apparently healthy cats in a chronically infected cattery. Sampling was performed with both a sterilized piece of carpet and a toothbrush applied to the entire body surface. Samples were inoculated on Sabouraud's media (with chloramphenicol and cycloheximide). Multiple (6) applications with the toothbrush were necessary to obtain a similar surface area of inoculation. Cultures were incubated at 27°C, then examined from day 5 to 21 for the presence and number of colonies of M. canis and other fungi. Some samples were inoculated twice (initially negative or with a low number of M.canis). A total of 112 cultures were performed (14 duplicates) from 44 cats. On day 21, infection was detected in 23 cats (54.7%): 20 (87%) with the carpet method and 21 (91%) with the toothbrush method. None of the replicated cultures allowed the detection of new cases but three were subsequently negative. In eight cases, only one to six colonies of M. canis were obtained. Both methods used are easy to perform on cats and have a similar sensitivity of approximately 90%. The carpet method is, however, much less expensive, easier to prepare, mail, store and inoculate. The lack of growth in some duplicate cultures (initial development of one or two colonies) may explain the limits of diagnosis of infection and justify the need for multiple inoculations of agar with the toothbrush method. Funding: Self‐funded.