Synergistic Effects of Efflux Pump Modulators on the Azole Antifungal Susceptibility of Microsporum canis

Virulence and Antifungal Susceptibility of Microsporum canis Strains from Animals and Humans

“…However, since low thermotolerance were observed also in animals without lesions, the role of thermotolerance in causing skin lesions should be further investigated. As regards the in vitro susceptibility testing, in this study, VOR, TER, PSZ had the highest antifungal activity against M. canis strains from all groups, suggesting that they might be drugs for an effective treatment of dermatophytosis in both humans and animals [ 18 ]. In particular, it has been shown that VOR has an effective in vitro and in vivo activity against M. canis specifically in the range of 0.01 to 0.5 μg/mL [ 36 , 37 , 38 ] and the PSZ has been demonstrated to show high fungicidal activity against all Microsporum spp.…”

“…Finally, the finding of low activities of ITZ and FLZ regardless of the origin of strains is most likely due to the common employment of these drugs to treat or prevent animal and human dermatophyte infections and might suggest that they are not an optimal choice for long term therapy [ 18 , 40 ]. Since the MIC data varied among M. canis strains from hosts with and without skin lesions, their association with virulence factors may be linked to the appearance of visible symptoms in M. canis infections in animals and humans.…”

“…Current treatment against dermatophytoses in pet animals includes the use of oral antifungals such as itraconazole (ITZ), ketoconazole (KTZ), terbinafine (TER), topical antifungal therapy, routine cleaning of the premises, limited confinement and treatment monitoring [ 7 , 16 ], whereas for humans, fluconazole (FLZ) represents the first line therapy in many European countries [ 17 ]. Azole resistance phenomena in M. canis is rarely reported, [ 18 ] although clinical evidence suggest that some of the infections are difficult to treat with azoles or TER [ 18 , 19 ]. Although a standardized antifungal susceptibility testing protocol for M. canis has not been developed [ 20 ], many studies on the antifungal therapy suggested that M. canis have low susceptibility to ITZ or FLZ [ 18 , 21 , 22 ].…”

“…Azole resistance phenomena in M. canis is rarely reported, [ 18 ] although clinical evidence suggest that some of the infections are difficult to treat with azoles or TER [ 18 , 19 ]. Although a standardized antifungal susceptibility testing protocol for M. canis has not been developed [ 20 ], many studies on the antifungal therapy suggested that M. canis have low susceptibility to ITZ or FLZ [ 18 , 21 , 22 ]. Interestingly, the above findings were observed in M. canis isolates from humans and animals with skin lesions [ 18 , 21 , 22 ], and most likely, might be due to an acquired azole resistance phenomenon which resulted from the recurrent use of these drugs for the treatment of infections [ 7 , 23 ].…”

“…Although a standardized antifungal susceptibility testing protocol for M. canis has not been developed [ 20 ], many studies on the antifungal therapy suggested that M. canis have low susceptibility to ITZ or FLZ [ 18 , 21 , 22 ]. Interestingly, the above findings were observed in M. canis isolates from humans and animals with skin lesions [ 18 , 21 , 22 ], and most likely, might be due to an acquired azole resistance phenomenon which resulted from the recurrent use of these drugs for the treatment of infections [ 7 , 23 ]. Nonetheless, the low antifungal susceptibility associated with the low expression of virulence factors in yeasts might explain the positive outcome of lesions on infected animals [ 15 ].…”