Micologia, Virologia e Microbiologia Clínica 01/02

Summary

This video lecture focuses on medical mycology, specifically fungal infections in humans, and the classification of mycoses. It introduces superficial mycoses, like pityriasis versicolor (commonly known as 'white spot'), caused by the Malassezia fungus. The presentation explains how these infections are typically asymptomatic, non-invasive, and occur in the outer layers of the skin and hair. The discussion includes the nature of the Malassezia fungus, its role in human microbiota, and conditions that promote infection. Additionally, the video covers other superficial infections such as piedra negra and piedra blanca, detailing their causes, symptoms, and diagnostic methods.

Takeaways

• 😀 The focus of the lesson is on medical mycology, which studies fungal diseases in humans and animals.
• 😀 There are over 100,000 fungal species, but only about 400 can cause diseases in humans.
• 😀 The four main classifications of medical mycoses are superficial, cutaneous, subcutaneous, systemic, and opportunistic.
• 😀 Superficial mycoses affect the outermost layers of the skin and hair, often causing only cosmetic issues without symptoms like itching or pain.
• 😀 Pityriasis versicolor (commonly known as white spot) is a chronic, asymptomatic superficial fungal infection caused by Malassezia species.
• 😀 Malassezia is a lipophilic yeast that can be part of the normal skin microbiota, but overgrowth can lead to infections.
• 😀 This infection is more common in areas with higher skin oil production, such as the face, shoulders, and chest, especially in tropical climates.
• 😀 Diagnosis of pityriasis versicolor involves direct microscopic examination, where fungal elements like yeasts and hyphae are observed.
• 😀 Piedra infections (black and white) are also superficial and benign, with the main difference being the fungi involved and the regions they affect.
• 😀 Piedra blanca (white piedra) is caused by Trichosporon and is less contagious, while piedra negra (black piedra) is caused by a different fungal species and is more contagious.
• 😀 Both piedra infections are more cosmetic than harmful, with no significant immune response from the body, and the fungi are typically confined to the surface of hair follicles.

Q & A

What is the focus of medical mycology?

Medical mycology is the branch of science that studies diseases caused by fungi, focusing on human and animal infections. The primary focus in this class is on human infections.

How many fungal species are known to cause diseases in humans?

Over 100,000 fungal species are known, but only about 400 of them are capable of causing diseases in humans.

What are the four types of mycoses in medical literature?

The four types of mycoses are cutaneous, subcutaneous, systemic, and opportunistic.

What is the main characteristic of superficial mycoses?

Superficial mycoses are non-invasive, asymptomatic, and generally only present as cosmetic issues on the skin or hair.

What is Pitiríase Vesicolor (Pano Branco) and its main cause?

Pitiríase Vesicolor, also known as Pano Branco, is a chronic, asymptomatic superficial fungal infection caused by the Malassezia fungus, particularly Malassezia furfur.

Where does Pitiríase Vesicolor typically appear on the body?

It typically affects areas of the skin with high oil content, such as the face, trunk, and shoulders.

Is Pitiríase Vesicolor contagious?

No, Pitiríase Vesicolor is not contagious. It is a fungal infection that already exists as part of the skin's microbiota, and it only causes issues when the balance between the fungus and the host is disrupted.

What factors predispose individuals to Pitiríase Vesicolor?

Factors include oily skin, intense sweating, hot and humid climates, poor nutrition, pregnancy, and weakened immunity due to conditions like chronic infections or steroid use.

What is the diagnostic method for Pitiríase Vesicolor?

The diagnosis is typically made through direct microscopy, where the fungus can be seen in the form of yeast cells and hyphae. A culture is less commonly done.

How do Piedra (both Black and White) differ from Pitiríase Vesicolor in terms of their causative agents and symptoms?

Piedra is caused by different fungi: Piedra blanca (white piedra) by Trichosporon and Piedra negra (black piedra) by Piedraia. While both are asymptomatic and superficial, Piedra negra is contagious, while Piedra blanca has low contagion. White piedra mainly affects the pubic, axillary, and facial hair, while black piedra affects the hair and other body areas like the pubic region.