M. canis Antifungal Resistance: Enzymatic Correlates and Drug Efficacy Original paper
Researched by:
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Karen Pendergrass
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Karen Pendergrass
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease—four years before the first published case study.
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Microbes
Microbes
Microbes, short for microorganisms, are tiny living organisms that are ubiquitous in the environment, including on and inside the human body. They play a crucial role in human health and disease, functioning within complex ecosystems in various parts of the body, such as the skin, mouth, gut, and respiratory tract. The human microbiome, which is […]
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Microsporum canis (M. canis)
Microsporum canis (M. canis)
OverviewMicrosporum canis (M. canis) is a zoophilic dermatophyte common in cats and dogs, responsible for 90% of feline dermatophytoses worldwide.[1][2] It has significant zoonotic potential, transmitting to humans through fomites or direct animal contact, causing severe superficial mycosis. M. canis is considered anthropo-zoophilic and can infect pediatric or immunocompromised patients, causing severe inflammatory responses such […]
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Karen Pendergrass
Researched by:
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Karen Pendergrass
ID
Karen Pendergrass
Microbiome Signatures identifies and validates condition-specific microbiome shifts and interventions to accelerate clinical translation. Our multidisciplinary team supports clinicians, researchers, and innovators in turning microbiome science into actionable medicine.
Karen Pendergrass
What was studied?
This study investigated the virulence enzyme profiles and antifungal susceptibility of 100 M. canis strains isolated from humans with tinea corporis and animals either with or without skin lesions. With concerns around Microsporum canis antifungal resistance, the study aimed to determine whether specific virulence factors (phospholipase [Pz], lipase [Lz], hemolysin [Hz], catalase [Ca], and thermotolerance [GI]) correlate with antifungal susceptibility and the clinical presentation of infection. Seven antifungal agents were tested using a modified CLSI broth microdilution method: itraconazole, ketoconazole, voriconazole, posaconazole, terbinafine, fluconazole, and griseofulvin. The overarching goal was to assess potential links between virulence, antifungal resistance, and the presence or absence of lesions in different hosts. Understanding Microsporum canis antifungal resistance helps in developing more effective treatment strategies. The research on M. canis antifungal resistance is increasingly vital given the rising resistance patterns identified.
Who was studied?
The analysis included 100 M. canis strains: 10 from humans diagnosed with tinea corporis, 64 from animals with visible skin lesions, and 26 from asymptomatic animals. These strains were confirmed via morphological and molecular identification, including ITS sequencing. Strains were phenotypically grouped by host origin and the presence of skin lesions to identify correlations between enzymatic activity, antifungal susceptibility, and lesion development. These observations provide insights into Microsporum canis antifungal resistance.
Most important findings
Among the virulence factors examined, several displayed statistically significant variation between host groups. Lipase (Lz) activity was markedly higher in M. canis strains isolated from animals without lesions, suggesting a possible protective function or a role in early colonization. In contrast, catalase (Ca) activity was elevated in strains from both animals and humans with skin lesions, indicating its potential involvement in oxidative stress defense and pathogenicity. Hemolysin (Hz) activity was also higher in symptomatic hosts and significantly correlated with reduced susceptibility to azole antifungals such as fluconazole and voriconazole, implicating Hz as a contributor to Microsporum canis antifungal resistance.
Additionally, thermotolerance (GI%) was lower in lesion-associated strains, suggesting impaired growth at elevated temperatures, though this trait did not directly correlate with antifungal resistance. Among the antifungals tested, voriconazole, terbinafine, and posaconazole demonstrated the highest efficacy across all isolates, while fluconazole and itraconazole showed comparatively higher MICs in symptomatic strains, raising concerns regarding their long-term therapeutic utility and highlighting issues associated with M. canis antifungal resistance.
| Virulence Factor | Observation in Lesion-Associated Strains |
|---|---|
| Catalase (Ca) | Elevated activity |
| Lipase (Lz) | Lower activity |
| Hemolysin (Hz) | Higher activity correlated with azole resistance, contributing to Microsporum canis antifungal resistance. |
| Thermotolerance | Lower in lesion-associated strains |
The positive correlation between high MICs for azoles and increased Ca/Hz activity in lesion-associated strains suggests that enzymatic virulence may contribute to antifungal resistance or vice versa. Continued study on M. canis antifungal resistance can provide deeper insights into these complex interactions.
Key implications
The findings highlight a potential dual role for virulence enzymes—both in facilitating tissue invasion and correlating with antifungal resistance profiles, particularly among azoles. Elevated catalase and hemolysin activities in strains from symptomatic hosts indicate a mechanistic link between oxidative stress evasion and diminished antifungal efficacy. These insights suggest that catalase and hemolysin could serve as biomarkers for aggressive M. canis infections and potentially guide treatment decisions. Moreover, identifying voriconazole, terbinafine, and posaconazole as the most active antifungals against M. canis reinforces their clinical utility, especially in resistant or recurrent cases. These data support the need for enzyme-targeted antifungal strategies and call for surveillance of antifungal resistance patterns in zoonotic dermatophytoses, especially concerning Microsporum canis antifungal resistance.