50 Questions
Which of the following is a common clinical feature of dermatophytosis?
Pruritus
Which species is the most common cause of dermatophytosis in dogs and cats?
Microsporum canis
What is the main mode of transmission of dermatophytosis?
Direct and indirect contact
Which of the following is a less common presentation of dermatophytosis?
Pseudomycetoma
Which diagnostic test for dermatophytosis is very sensitive and provides faster results than culture?
Fungal PCR
What is the recommended method for collecting a sample for fungal culture?
Using a toothbrush
Which test is used to find abnormal hairs for direct examination and culture?
Wood's lamp examination
What is the most common species of Malassezia found in the microbiome of normal animals?
Malassezia pachydermatis
Which host factors can contribute to Malassezia infection?
Anatomical features
What is the recommended method for diagnosing Malassezia infection?
Fungal culture
Which of the following is a common source of animal disease caused by dermatophytes?
Zoophilic fungi
Which type of mycosis is the most common in skin?
Superficial mycosis
Which of the following is an example of a skin commensal fungi?
Malassezia
Which type of fungi are adapted for the environment?
Geophilic fungi
Which type of mycosis is uncommon and associated with hypersensitization?
Hypersensitisation mycosis
Which of the following is NOT a common type of mycosis in the skin?
Tissue mycosis
Which of the following is a frequent skin contaminant but usually does not cause infection?
Saprophytic fungi
Which of the following is NOT a type of dermatophyte?
Saprophytic fungi
Which of the following is a type of mycosis that can affect deeper tissues?
Deep mycosis
Which of the following can atopic dogs become sensitized to?
Environmental saprophytes
Which of the following is a characteristic of Malassezia dermatitis/otitis?
It is almost always a secondary infection
Which of the following is a potential consequence of Malassezia colonization in immunocompromised individuals?
Infections
What is the most common clinical presentation of Malassezia dermatitis in dogs?
Erythema, grease, scale, crust
Which of the following areas are commonly affected by Malassezia dermatitis in dogs?
All of the above
What is the most appropriate method to identify Malassezia at affected sites in dogs and cats?
All of the above
What number of Malassezia is considered normal in cytology?
No absolutes - low numbers significant if Malassezia hypersensitivity
What is the most common cutaneous manifestation of dermatophytes?
Alopecia, scale, crust
Which of the following is a characteristic of dermatophytes?
They are contagious
What is the recommended method for diagnosing dermatophytes?
All of the above
What is the most common cause of pruritic dermatitis/otitis in dogs and occasionally cats?
Malassezia
What are the three categories of fungi found on the skin?
skin commensals, transient contaminants, active pathogens
Which type of fungi are most commonly associated with animal disease?
zoophilic
Which type of mycosis is the most common in the skin?
tissue mycosis
What is the main mode of transmission for dermatophytosis?
contact with infected animals or contaminated objects
What is the most common cause of pruritic dermatitis/otitis in dogs and occasionally cats?
Malassezia infection
Which host factors can contribute to Malassezia infection?
immunocompromised individuals, allergic individuals
What are the stages of infection in dermatophytosis?
Skin microtrauma & moisture, leading to inoculation and germination of infective arthrospores hence germ tubes penetrate stratum corneum hence growth of fungal hyphae leading lesions (foci within 5-7 days)
What is the mode of transmission for dermatophytosis?
Direct contact / indirect (fomites)
Which species are commonly affected by dermatophytosis?
Cow, horse, cat; less common in dog/other species
What are the common clinical features of dermatophytosis?
Caused usually by Microsporum spp, Trichophyton spp; folliculitis alopecia - usually fairly well-demarcated; adherent scale; +/- erythema, crust, comedones; occasional pustules; variable pruritus
What is the recommended method for diagnosing dermatophytosis?
Combination of tests including direct examination of hair/scales, Wood's lamp, fungal culture, and PCR
What is the most common cause of pruritic dermatitis/otitis in dogs and occasionally cats?
Malassezia species
What are the clinical presentations of Malassezia dermatitis/otitis in dogs?
Pruritus, erythema, grease, scale, crust, lichenification, hyperpigmentation, malodourous lesions affecting various areas of the skin including ears, lips, muzzle, interdigital skin, flexor surfaces/medial aspects of limbs, ventral neck/body, axillae, perineum, and paronychia (claw fold infection).
What are the clinical presentations of Malassezia dermatitis/otitis in cats?
Variable pruritus, otitis, chin acne, paronychia, secondary to certain systemic diseases.
What are the diagnostic methods for identifying Malassezia at affected sites in dogs and cats?
Cytology with stained acetate tape strip or stained impression smear using x40- x100 (oil immersion) objective.
What is the recommended method for diagnosing Malassezia infection?
Cytology to identify Malassezia at affected sites and assess response to antifungal therapy.
What are the most common cutaneous manifestations of fungi?
Superficial tissue mycoses caused by dermatophytes and Malassezia.
What is the most common cause of pruritic dermatitis/otitis in dogs and occasionally cats?
Malassezia infection.
What are the host factors that can contribute to Malassezia infection?
Immunocompromised status, certain systemic diseases, and dysbiosis (imbalance of organisms present in normal microbiome).
What are the potential consequences of Malassezia colonization in immunocompromised individuals?
Reported infections and increased risk of disease.
Study Notes
Dermatophytosis
- A common clinical feature of dermatophytosis is pruritic dermatitis/otitis in dogs and occasionally cats.
- Microsporum and Trichophyton are common causes of dermatophytosis in dogs and cats, with Microsporum canis being the most common species.
- The main mode of transmission of dermatophytosis is through direct contact with infected animals or contaminated fomites.
- Less common presentations of dermatophytosis include papular or pustular lesions, or lesions that resemble eczema or seborrheic dermatitis.
- The Wood's lamp test is a diagnostic tool for dermatophytosis, and it is very sensitive and provides faster results than culture.
Malassezia
- Malassezia pachydermatis is the most common species of Malassezia found in the microbiome of normal animals.
- Host factors that can contribute to Malassezia infection include allergies, immunosuppression, and seborrheic skin disease.
- The recommended method for diagnosing Malassezia infection is through direct examination of skin scrapings or cytology.
- Malassezia dermatitis/otitis is characterized by pruritic skin lesions, excoriations, and a strong unpleasant odor.
- In immunocompromised individuals, Malassezia colonization can lead to more severe infections, such as pneumonia or sepsis.
Fungi
- The three categories of fungi found on the skin are saprophytic fungi, opportunistic fungi, and dermatophytes.
- Dermatophytes are the most common type of fungi associated with animal disease.
- The most common cutaneous manifestation of dermatophytes is pruritic dermatitis/otitis.
Diagnostic Methods
- The recommended method for collecting a sample for fungal culture is through skin scrapings or biopsy.
- The Wood's lamp test and direct examination of skin scrapings or cytology are used to diagnose dermatophytosis and Malassezia infection, respectively.
- The trichogram test is used to find abnormal hairs for direct examination and culture.
Miscellaneous
- Atopic dogs can become sensitized to Malassezia.
- Malassezia colonization is more common in certain breeds, such as Basset Hounds and West Highland White Terriers.
- The stages of infection in dermatophytosis include incubation, invasion, and spread of infection.
- Dogs and cats are commonly affected by dermatophytosis.
- The main mode of transmission for dermatophytosis is through direct contact with infected animals or contaminated fomites.
Test your knowledge on fungi found on the skin and their role in skin disease. Learn about skin commensals, transient contaminants, and active pathogens. Explore the different types of tissue mycosis and their prevalence.
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