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Understanding Fungal Pathogenesis and Host Interactions

This study delves into the complex interaction between endogenous and exogenous fungal species and compromised host tissue and immune system. Various effects on fungus, host tissue, and immune system are explored, shedding light on the pathogenesis of fungal infections. The text discusses the factors triggering changes in fungal morphology and metabolism, resulting in enhanced adherence, tissue invasion, resistance to antifungal drugs, and immune responses. It also covers the impacts on innate defense mechanisms, chronic inflammation, and the role of cell-mediated immunity. Furthermore, the study discusses the detection of fungi in different environments and explains the introduction, causes, classification, and predisposing factors of Candidiasis in detail.

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Understanding Fungal Pathogenesis and Host Interactions

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  1. Pathogenesis of Fungus FUNGUS ENDOGENOUS SPP. EXOGENOUS SPP. COMPROMISED HOST TISSUE AND/OR IMMUNE SYSTEM EFFECTS ON FUNGUS EFFECTS ON HOST TISSUE AND IMMUNE SYSTEM

  2. EFFECTS ON FUNGUS Unknown host factors trigger changes in fungal morphology and metabolism with some results: Improved fungal adherence and growth on host surfaces. 2. Ability to invade host tissue. 3. Production of antiphagotic and cytotoxic factors. 4. Ability to develop resistance to antifungal drugs

  3. EFFECTS ON HOST TISSUES AND IMMUNE SYSTEM Innate defence mechanism less effective. 2. Increased fungal load on host surfaces. 3. Phagocytosis / Opsonization less effective. 4. Fungal invasion of deeper tissue with tissue destruction. 5. Chronic inflammatory response.

  4. Pathogenesis of Fungus FUNGUS ENDOGENOUS SPP. EXOGENOUS SPP. COMPROMISED HOST TISSUE AND/OR IMMUNE SYSTEM EFFECTS ON FUNGUS EFFECTS ON HOST TISSUE AND IMMUNE SYSTEM Cell mediated immunity

  5. Cell mediated immunity Normal Defective Activated macrophages with cytokine release Chronic infections Systemic disease Locally destructive disease

  6. Activated macrophages with cytokine release Elimination of fungus from deeper tissues. 2. Healing. 3. Return of fungus to commensal state or elimination.

  7. Pathogenesis of Fungus • Normal immune system have high natural resistance to most fungal infections. • Some fungi have developed to evade parts of the host defence mechanism along with the number of non fungal factors that predispose the host to infection. • This predisposing factors effect the innate , humoral , cell-mediated responses.

  8. Pathogenesis of Fungus • Fungi can be detected when changes in the surrounding environment occurs; examples: Fungus inhaled(lungs) /Microclimate of an endogenous fungus changes (within the host) Severe reduction of salivary volume in the mouth Such change causes fungus to alter its morphology and metabolism, leading to cell proliferation and possibly invasion to host tissue.

  9. Candidiasis

  10. Introduction to Candidiasis • Commonest fungal infection in the oral cavity • Synonyms: Candidosis, • Moniliasis • Commonest manifestation: • Oral involvement • -solely confined to the oral mucosa • -part of any or several mucocutaneous candidiasis syndrome

  11. Introduction to Candidiasis Causative organism: Candidaalbicans dimorphisms: yeast like fungus occurring in yeast form and mycelial form. Other species: 1. Candida stellatoidea 5. Candida famata 2. Candida tropicalis 6. Candida rugosa 3. Candida parapsilosis 7. Candida krusei 4. Candida pseudotropicalis 8. Candida guilliermondi

  12. Classification to Candidiasis Primary oral candidiasis 2.Chronic form: a. Hyperplastic b. Nodular c. Plaque like d. Erythematous e. Pseudomembranous • Keratinized primary lesion super infected with Candida: • a. Leukoplakia • b. Lichen planus • c. Lupus erythematosus 1. Acute form: a. Pseudomembranous b. Erythematous 3. Candida associated lesion: a. Denture stomatitis b. Angular stomatitis c. Median rhomboid glossitis

  13. Secondary candidiasis Oral manifestation of systemic mucocutaneous candidiasis (candida endocrinopathy syndrome).

  14. Predisposing factors to Candidiasis • Altered local resistance to infection • Compromised immune system function • Generalized patient debilitation

  15. 1. Altered local resistance to infection Conditions Mechanism Poor oral hygiene Promotes organism adherence and colonization Xerostomia Absence of antimicrobial and flushing effect of saliva Dentalappliances Isolates mucosa from saliva and functional cleansing serve as organism reservoir Recentantibiotic treatment Inhibits competitive oral bacteria

  16. 2. Compromised immune system function Conditions Mechanism Earlyinfancy Immune competence has not completely developed Genetic immune deficiency Specific humoral or cellular defects AIDS Deficient cellular immune response Corticosteroids theraphy Inhibition of immune function Pancytopenia Depletion of circulating leukocytes caused by chemotherapy ,aplastic anaemia and similar hemopoietic disorders

  17. 3. Generalized patient debilitation Conditions Mechanism Anemia Malnutrition, Malabsorption Epithelial thinning and altered maturation, poor tissue oxygenation Diabetes mellitus Recurring hyperglycaemia and mild ketoacidosis Advanced systemic diseases Metabolic toxicity or limited blood prefusion of tissue

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