LU Overview Flashcards
Tinea
Group of superficial fungal infections.
Fungal Infections Categories
- Superficial mycoses- involve the outermost layers of the skin and hair
- Cutaneous mycoses- penetrate deeper into the epidermis, hair, and nails
- Subcutaneous mycoses - involve the dermis, subcutaneous tissue, muscle, and fascia (tinea pedis, tinea cruris, and tinea corporis)
- Systemic or endemic mycoses - extend beyond a local site of infectio into organs, such as the lungs or blood
Fascia
Sheet of fibrous tissue that covers the body beneath the skin, also encloses muscles and groupos of muscles seperating them
Erythematous
Redness of the skin
Types of Tinea
- Tinea Pedis (athletes foot)- affects the foot and toes
- Tinea Corporis (RIngworm) - affects the trunk and extremities
- Tinea Cruris ( Jock itch) - Affects the groin
Tinea Presentation
Scaling patch with raised margin showing variable inflammation, ith diminished infammation toward the center of the lesion
Diagnostic methods of Infections
- KOH - aids in visualizing hypae and confirming diagnosis of dermatophyte infection
- Woods lamp (ultraviolet light) - limited usefullness, most dermatophytes currently see in the US do not fluoresce
- Fungal Culture - slow and expensive but useful to confirm a diagnosis when long-term oral therapy is being considered
Antifungal Spectrum
describes the range of activity of an antifungal agent against fungi.
Broad spectrum- antifungal agent that inhibits a wide variety of fungi, including both yeast and molds.
Narrow-spectrum - agent that is active against a limited number of fungi
Fungistatic Activity
Describes the level of antifungal activity that inhibits growth of an organism. It is determined in vitri by testing a standardized concentration of organisms against a series of antifungal dilutions
Minimum Inhibitory Concentration (MIC) - lowest concentration of the drug that inhibits growth of the organism
Fungicidal Activity
Describes the ability of an antifungal agent to kill an organism in vitro or in in vivo.
Minimum Fungicidal Concentration (MFC) - Lowest concentration of the drug that kills 99.9% of the test population
In Vitro
Studies in experimental biology are those that are conducted using components of an organism that have been isolated from their usual biological surroundings in order to permit a more detalied or more convenient analysis than can be done with whole organism.
In Vivo
Studies are those that are conducted with living organisms in their normal intact state
Antifungal Combinations
Combination of agents that may be used to :
- Enhance efficacy in the treatment of refractory fungal infection
- broaden the spectrum of empiric antifungal therapy
- prevent the emerence of resistant organisms
- achieve a synergistic killing effect
Topical Therapy
- Tinea infections are most commonly treated with topical agents
- Most topical drugs indicated for cutaneous infections are fungistatic, they increase the permeability of th efungal cell wall, causing the contents of the cell to leak out and the cell to die
- Classes Most widely used
- Imidazoles
- Allylamines
- Pyridones
Imidazoles
- belong to the class of antifungal agents called azoles. In the treatment of fungal infections of the skin, imidazoles are used both topically and systemically.
- Agents block the synthesis of Ergosterol, which is critical in the development and maintenance of fungal cell membranes and hyperpermeability.