Monday, October 7, 2013

Clinical Mycology

Fungi constitute a group of non motile, eukaryotic organisms that have definite cell walls, devoid of chlorophyll and reproduce by means of spores either sexual or a sexual. Classification: Fungi may take the following forms 1-Yeast: uni cellular spherical or ovoid in shape such as Candida species. 2-Mold: multicellular such as dermatophytes. 3- Dimorphism: is a character of some pathogenic fungi which grow as molds in natural environment and in lab. Fungal Infections: They are classified into: cutaneous, sub-cutaneous, deep and opportunistic mycosis Type Causative Fungus Infection A) Cutaneous Malassezia Tinea versicolor Dermatophytes (Epidermophyton, Trichophyton,Microsporum) Ring worm of skin, nails and hair. Subcutaneous Sporothrix Sporotrichosis of lymph vessels and lymph nodes Several genera Mycetoma (Madura foot) chronic granuloma discharging pus especially of leg and foot Systemic Histoplasma Pulmonary or disseminated histoplasmosis Coccoidiodes Pulmonary or Erythema Nodosum Blastomyces Pulmonary or disseminated Paracoccoidiodes Pulmonary, disseminated Opportunistic Candida Candidiasis: oral thrush, vaginitis or dissiminated Aspergillus Aspergillosis: pulmonary, aspergilloma, toxicosis (ASP, Flavus produce aflatoxin which is hepatocarcinogen. Cryptococcus Cryptococcal meningitis or pulmonary cryptococcus Mucor Mucor mycosis of bllod vessels esp. of paranasal sinus, lung, gut. Diabetic ketoacidosis, organ transplant and leukemic patients are mostly susceptible. Laboratory Diagnosis: A) Collection of samples: according to site of infection, cutaneous (hair, nail, skin), subcutaneous (abscess, sinus, fistula), systemic (blood,sputum, CSF, bone marrow, urine, faeces). B) Diagnostic methods: 1-Direct microscopic examination using KOH-indian ink,Giemsa –periodic acid Schiff. 2-Fungal culture: Common media is Sabouraud s agar. 3-Direct antigen detection by immunoelectrophoresis or latex. 4- Serology useful for diagnosis and prognosis of systemic fungal infections.

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