The first report of terbinafine resistance <i>Microsporum canis</i> from a cat

Abstract

A 2-year-old, exotic shorthair cat presented with baldness and mild scaling on trunk that was confirmed as Microsporum canis (M. canis) infection by the following methods. Wood’s lamp and trichogram were used to demonstrate fungal elements suggestive of dermatophytosis consistent with M. canis. Dermatophyte test medium (DTM) and polymerase chain reaction (PCR) were used for identification. E-test and broth microdilution test were then utilized to estimate antifungal minimal inhibitory concentrations (MICs) towards ITZ and TRF respectively. The strain was isolated from the patient and revealed TRF MIC >32 µg/ml and ITZ MIC 0.023 µg/ml. Patient was cured of dermatophytosis with systemic ITZ.

In vitro activities of 15 antifungal drugs against a large collection of clinical isolates of Microsporum canis

“…Interestingly, we found that two animal isolates and one human isolate responded to terbinafine at high MICs (4‐8 and 4 μg/mL, respectively), which is, however, consistent with previous studies reporting high MICs of terbinafine for M. canis clinical isolates. A terbinafine‐resistant M. canis strain (MIC > 32 μg/mL) was obtained from a short‐hair cat, which was then treated with systemic itraconazole, and M. canis isolates responding to high MICs (4 and 8 μg/mL) of terbinafine were found to be associated with human infections . In this study, the MIC range for itraconazole against M. canis isolates (0.001‐2 μg/mL) was the same as that reported before; similar itraconazole MICs of ≤1 μg/mL were also observed for M. canis strains in other studies .…”

“…32 Interestingly, we found that two animal isolates and one human isolate responded to terbinafine at high MICs (4-8 and 4 μg/mL, respectively), which is, however, consistent with previous studies reporting high MICs of terbinafine for M. canis clinical isolates. A terbinafine-resistant M. canis strain (MIC > 32 μg/mL) was obtained from a shorthair cat, which was then treated with systemic itraconazole, 16 and M.…”

“…Despite the medical importance of M. canis infections, there are limited in vitro data on the susceptibility of M. canis to antifungal drugs, including new generation triazoles and imidazoles. Therefore, the aim of the current study was to comprehensively evaluate the in vitro activity of new azoles and comparator drugs against a large panel of M. canis isolates using a microdilution assay.…”

“…12 M. canis is among the best-known agents of human tinea capitis, tinea corporis and tinea manum in different geographical areas; however, it has been rarely associated with tinea unguium and tinea faciei. [13][14][15] Previous studies have documented low in vitro susceptibility towards fluconazole, itraconazole, ketoconazole, terbinafine, naftifine, griseofulvin and ciclopirox [16][17][18] ; clinical isolates of T rubrum and T interdigitale that are resistant to allylamines, particularly terbinafine, with point mutations in the squalene epoxidase-encoding gene, have also been reported. [19][20][21] Owing to problems with molecular identification, the distinction between the anthropophilic T interdigitale and zoophilic T mentagrophytes leads to some taxonomical confusion.…”

“…[19][20][21] Owing to problems with molecular identification, the distinction between the anthropophilic T interdigitale and zoophilic T mentagrophytes leads to some taxonomical confusion. [22][23][24] Despite the medical importance of M. canis infections, there are limited in vitro data on the susceptibility of M. canis to antifungal drugs, 16 including new generation triazoles and imidazoles.…”