BMS1-12. Fungi Important in Dentistry -Assist. Prof. Dr. Güner Ekiz (1).pdf

Fungi Important in Dentistry Assist. Prof. Dr. GÜNER EKİZ DİNÇMAN NEU Faculty of Pharmacy Department of Pharmaceutical Microbiology 01.11.2023 1 Opportunistic pathogens Microorganisms – Do not cause disease in a...

Fungi Important in Dentistry Assist. Prof. Dr. GÜNER EKİZ DİNÇMAN NEU Faculty of Pharmacy Department of Pharmaceutical Microbiology 01.11.2023 1 Opportunistic pathogens Microorganisms – Do not cause disease in a healthy host – Take advantage of a host with a weakened immune system – E.g. some bacteria, viruses, fungi and protozoa 2 What are the opportunities? Physiological factors e.g. elderly, pregnancy and infancy Local factors e.g. mucosal irritations, poor dental hygiene, localized radiotherapy, xerostomia Medications e.g. broad spectrum antimicrobial therapy, cytotoxic drugs, immunosuppressive drugs, Steroid inhalers and systemic steroids Nutritional factors e.g. Iron, folate, vitamin B12 deficiencies, malnutrition Systemic disorders e.g. Diabetes, hypothyroidism, Addison’s disease Immune defects e.g. HIV infection, AIDS, thymic aplasia Malignancies e.g. acute leukaemia, agranulocytosis Xerostomia due to irradiation, Sjogren's syndrome, drug therapy 3  Fungal Infections (Mycoses) Superficial – Hair – Skin Cutaneous – Keratinized tissue Subcutaneous Systemic Opportunistic 4  Mycoses Superficial Mycoses: superficial infections of skin and hair Cutaneous Mycoses: infections of keratinized tissue-skin, hair, nails-caused by dermatophytes Subcutaneous Mycoses: usually introduced by trauma/breach of dermal tissue - infections of subcutaneous fascia, muscle and deeper epidermal layers Systemic mycoses due to primary pathogens (systemic dimorphic fungi) The primary deep pathogens usually gain access to the host via the respiratory tract. Systemic mycoses due to opportunistic pathogens Opportunistic fungi causing deep mycosis invade via the respiratory tract, alimentary tract, or intravascular devices. All three (superficial, subcutaneous, and cutaneous mycoses) are typically noninvasive infections. Systemic mycoses, on the other hand, can be life threatening, especially when the host is immunocompromised. 5 6  Oral Fungal Infections Infection Pathogen Candidiasis Candida albicans, C. tropicalis, C. glabrata, C. parapsilosis, C. krusei, C. kyfer, C. dubliniensis Aspergillosis Aspergillus fumigatus Cryptococcosis Cryptococcus neoformans Histoplasmosis Histoplasma capsulatum Blastomycosis Blastomyces dermatitidis Zygomycosis Orders Mucorales and Entomophthorales Coccidioidomycosis Coccidioides immitis Paracoccidiomycosis Paracoccidioides brasiliensis Penicilliosis Penicillium marneffei Sporotrichosis Sporothrix schenckii Geotrichosis Geotrichum candidum 7 8  Oral Fungal Infections Most solitary or primary oral fungal infections are rare with the exception of oral candidiasis! Candidiasis is the leading infection that most dental practitioner will see in clinical practice. 9  Candida species ØCandida species: normal residents of the oral microflora! ØDimorphic yeast ØOver 200 different species, only a few of these implicated in human infection: Candida albicans Candida glabrata Candida krusei Candida tropicalis Candida kefyr Candida parapsilosis Candida guilliermondii C. albicans accounts for over 80% of oral cavity isolates! 10  Candida - Morphology Ability to grow in several morphological states including: budding yeast cells, pseudohphae true filamentous hyphae Yeast cells are essential for dissemination, while hyphal forms essential for invading mucosal surfaces! The morphology switch between budding yeast and hyphal growth is triggered by host environmental cues, including temperature, pH, serum, and CO2 11 12  Oral Candidiasis Host related factors are important on the development of oral candidiasis. host defenses becoming compromised breakdown of the normal skin or mucosal barrier disturbance of the host by external factors (e.g. broad- spectrum antibiotic therapy…) other internal/external risk factors 13 Host related factors associated with oral candidiasis 14 Types of Oral Candidiasis ØPseudomemranous candidiasis ØAcute erythematous candidiasis ØChronic hyperplastic candidiasis ØChronic erythematous candidiasis Other secondary forms of oral candidiasis ØAngular cheilitis ØMedian rhomboid glossit ØChronic mucocutaneous candidiasis 15 16  Pseudomemranous candidiasis (Oral Thrush) White plaque-like lesions on the oral mucosa Lesions can be removed by gentle scraping Frequently found in the mouths of neonates and in the elderly Diabetics Long term use of corticosteroids, antipsychotics, antibiotics Immune dysfunction HIV infection, AIDS… 17  Acute erythematous candidiasis Characterized by the presence of painful reddened patches on the oral mucosa Typically on the dorsum of the tongue Frequently associated with the administration of a broad spectrum antibiotic – Particularly if the patient also uses a steroid inhaler Previously known as “antibiotic sore mouth” 18  Chronic hyperplastic candidiasis The condition can occur any site on the oral mucosa – Most frequently encountered as bilateral white patches in the buccal commissure region. – Lateral border of the tongue and palate Highest prevalence seen in middle aged men who are tobacco smokers Lesions cannot be removed by gentle scraping without bleeding Two lesion types: homogeneous & heterogeneous Heterogeneous form is prone to malignant transformation! 19  Chronic erythematous candidiasis Most frequently encounter form of oral candidiasis Candida-associated denture stomatitis This infection presents as reddening of the mucosa beneath the fitting surface of a denture Up to 65% of denture weavers have clinical signs of this condition Inadequate oral hygiene/presence of a poorly fitting denture are strongly associated with this condition 20  Angular cheilitis Characteristically presents as erythematous lesions at the corners of the mouth Mixed bacteria-fungi infection Staphylococcus aureus or streptococci are also present 21  Median rhomboid glossitis Symmetrical shaped area in the middle of the dorsum of the tongue Chronic condition and represents atrophy of the filiform papillae Strongly associated with both smoking and the use of inhaled steroids. 22  Chronic mucocutaneous candidiasis (CMC) Chronic condition of skin, mucous membranes and nails Relatively rare congenital conditions are associated with CMC Key predisposing factor: Impaired cellular immunity against Candida 23  Uncommon oral fungal infections Aspergillosis Aspergillus species (a mold) ≥ 800 species (ubiquitous in the environment) clinically important strains: – Aspergillus fumigatus – Aspergillus niger – Aspergillus flavus Second most common opportunistic fungal infection Most commonly portal of entry is by inhalation of fungal spores into the sinuses & respiratory track 24  Aspergillosis Commonly associated with high dose of corticosteroid use, organ and marrow transplantation, increase use of immunosuppression Lungs are commonly affected Less commonly affect maxillary sinuses Oral lesions are typically black or yellow necrotic soft tissues 25 Aspergillus species 26 Cryptococcosis Cryptococci (spherical yeasts) surrounded by a large polysaccharide capsule (an important diagnostic feature) Cryptococcus is the most common fungal pathogen responsible for meningitis Cryptococcus neoformans, usually isolated in pigeon’s and other birds’ droppings Usually affects immunocompromised patients (highest risk patients with advanced AIDS) Oral Cryptococcosis: superficial ulcers, violaceous nodules, granuloma, cancerous looking lesions, or draining sinuses Necrosis of alveolar bone Nonspecific chronic ulceration of the buccal and palatal mucosa mucosa due to cryptococcosis 27 Mode of transmission of C. neoformans 28 C. neoformans-morphology 29 Histoplasmosis Histoplasma capsulatum (a dimorphic fungi) Histoplasma capsulatum Two forms; pulmonary and mucocutaneous Mucocutaneous form cause ulcerative/erosive lesions on tongue, palate and buccal mucosa Oral lesions: single ulcers, long term and may or may not be painful Always misinterpreted as malignant ulcers Biopsy is mandatory 30 Blastomycosis Nonspecific papillary nodular Blastomyces dermatitidis lesion on the It presents as a pulmonary hard palate infection after the inhalation of Extensive spores, and it may be either ulceration involving asymptomatic or have severe the skin of the face life-threatening complications and neck like acute respiratory distress syndrome. Oral lesions are rare May produce ulcerated mucosal lesions in the oral cavity 31 Mucormycosis Caused by a saprophytic fungi found in soil, bread molds, decaying vegetation etc. (Mucor, Rhizopus, Absidia, Cunninghamella) Inhalation of fungal spores or direct penetration through the skin Usually present as a palatal necrosis or ulcerations Extends to adjacent structures causing extensive tissue necrosis and invasion of brain Organ transplant, uncontrolled diabetics, high-dose glucocorticoids, malnutrition, poor wound care 32 Rhizopus stolonifer Diagnosis & Therapy 33 Diagnosis 34 Diagnosis of deep seated oral fungal infections Biopsy Pathologist should be given patients’ medical history e.g. immune suppression Patients with deep oral fungal infections must be referred to medical specialists for further evaluation Blastomycosis: smear/culture, Direct immunostaining, DNA probes Cryptococcosis: microscopy/staining, serology Histoplasmosis: microscopy/staining, serology, skin tests Mucormycosis: microscopy/Histology, smear/culture 35 Targets of some antifungal agents 36 Antifungals used in the management of candidiasis 37 The most commonly used antifungals for specific clinical indications 38 39 40