common fungi causing ent diseases
TRANSCRIPT
Microbial World
Prokaryotes:1. Bacteria2. Archae
Eukaryotes1. Algae2. Fungi3. Protozoa4. Parasites
Fungi
Features: Cell wall: Chitin Cell membrane:
Ergosterol Zymosterol
Aerobic/ facultatively anaerobic Mostly microscopic Moisture essential for growth
Types of Fungi Yeasts:
Single celled Reproduction:
Budding
Molds: Long filaments
(hyphae) Form mycelium Septate/ Non
septate
Dimorphic
Importance Biologic recycling of organic matter Preparation of foods:
Beer Cheese Bread Wine Mushrooms
Economic impact: Plant diseases Source of biologically active compounds:
•Hallucinogens•Adrenergic alkaloids•Vitamins•Mutagens
•Carcinogens•Antibiotics •Immunosuppressive agents•Potential anticancer substances
Groups1. Zygomycetes:
Bread moulds (Rhizopus)
Food spoilage organisms
Rhizomucor
2. Basidiomycetes: Common
mushrooms Cryptococcus Malassezia
3. Ascomycetes: Aspergillus Histoplasma Coccidioides Candida Pneumocystis Sporothrix Dermatophytes
4. Deuteromycetes (Fungi Imperfectii):
Medically & economically imp fungi
Penicillin producing
Types of Fungal Diseases
1. Fungal allergies2. Mycotoxicoses3. Mycoses
Fungal Allergies Strong hypersensitivity reactions against:
Fungal spores Fungal components
Do not require: Growth Viability
Depending upon the site of deposition of allergens:
Rhinitis Sinusitis Bronchial asthma Alveolitis Generalized pneumonitis
Mycotoxicoses
Mycetismus Mycotoxins:
Amatoxins Phallotoxins Aflatoxin Ochratoxin Sporidesmin Zearalenone Sterigmatocystin
Target organ: Liver
Mycoses
Actual growth of a fungus on a human or animal host
Establishment of mycoses depends upon:
Host defenses Size of innoculum Route of exposure Virulence of the fungus
Clinical Classification of Mycotic Infections
Superficial: Pityriasis versicolor Tinea nigra
Cutaneous: Candidiasis Dermatophytosis
Subcutaneous: Rhinosporidiosis Rhinoentomophthoromyco
sis
Systemic: Histoplasmosis Paracoccidioidomycosis Candidiasis Cryptococcosis Aspergillosis Mucormycosis
Specimen Collection, Handling & Transport
Sample Collection: Primary criterion for diagnosis of mycotic infections Transportation & processing done ASAP
Tissue from site of active disease- ideal Most common specimens:
Respiratory secretions Hair Skin Nail Tissue Blood Bone marrow CSF
Respiratory Specimen
Viscous material (Tracheal aspirate): Cotton Swab Specimen digested with trypsin & concentrated
Sputum: Deep cough early in the morning Nebulizer to induce sputum
Collected into a sterile screw top container
Media: Non selective Media with antibiotics
KOH preparation
Mucin Collection
Nasal decongestant spray Flush with 20ml N/S Forceful exhalation through nose Return collected in sterile pan
Skin: 70% isopropyl alcohol before sampling Scraped from outer edge of a surface
lesion
Blood: Transport medium required
Exudates/ Pus: Sterile sealed container
Diagnosis
Direct microscopic examination
Culture Serology
Direct Microscopic Examination
Wet preparations: KOH mount India Ink Calcofluor white
Histologic stains: Periodic- Acid Schiff (PAS ) stain Grocott- Gomori methenamine silver nitrate
(GMS) stain H&E stain Giemsa stain Masson- Fontana stain
Culture
Culture Media: Saboraud’s Dextrose Agar SDA with antibiotics Brain Heart Infusion (BHI) agar enriched
with blood & antibiotics
Incubation: Temp: 25-30°C (37°C for dimorphic fungi) Duration: 4-6 weeks
Candida Candida: Part of normal flora of skin, mucus
membranes & GIT Candidiasis: Most common systemic mycoses Pathogenic strains:
C. albicans C. tropicalis C. glabrata C. krusei
Clinical Classification of Candidiasis: Cutaneous & Mucosal candidiasis:
Thrush Stomatitis Esophagitis
Systemic Candidiasis Esophagitis
Chronic Mucocutaneous Candidiasis
Predisposing factors: Cutaneous & mucosal
candidiasis: Physiologic:
Pregnancy Old age Infancy
Traumatic Hematologic: AIDS DM Iatrogenic:
Antibiotics Steroids
Systemic Candidiasis: Immunosuppression Surgery Steroids Malignancies Cytoxic drugs
Morphology Dimorphism:
Yeast cells True hyphae Pseudohyphae Germ tubes
Microscopy: Spherical/ ellipsoidal budding
yeasts Size: 3-6 μm Cornmeal agar: Chlamydiospores
Culture: Species cannot be differenciated Within 24-48hrs Raised Cream coloured Opaque 1-2mm Hyphae penetrating the agar
medium
Aspergillus
Ubiquitous molds Numerous species Approx 20 cause human infection Pathogenic species:
A. fumigatus A. flavus: Nose & PNS A. niger: systemic disease in
immunocompromised
Clinical diseases: Otomycosis Fungal rhinosinusitis
Morphology Microscopy:
Conidiophores Expand into large vesicles at the
end Covered with phialides
Culture: Powdery Pigmented
A. fumigatus: Gray, green A. flavus: Yellow- green A. niger: Black
Aspergillus niger & flavus
Mucormycosis Phycomycosis,
zygomycosis Molds Class: Zygomycetes Order: Mucorales Fungi:
Ubiquitous Thermotolerant Saprophytes
At risk patients: Acidosis Leukemia Immunocompromise
Etiologic agents: Rhizopus oryzae R. rhizopodiformis Absidia corymbifera R. pusillus Rhizomucor spss. Mucor spss.
Clinical manifestations: Rhinocerebral
mucormycosis Thoracic mucormycosis Cutaneous infections
Morphology
Microscopy: Broad Sparsely septate hyphae (10μm) Twisted & ribbonlike Branching at rt. angles
Culture: Rapid growth Abundant, cottony aerial mycelia
Paracoccidioidomycosis C/A: Paracoccidioides brasiliensis Chronic granulomatous disease:
Mucous membranes Skin Respiratory system
Most cases from Brazil Invade mucous memb of mouth→ teeth fall
out White plaques in buccal mucosa Histologically: Captain’s wheel
Cryptococcosis C. neoformans Distinctive yeast Diseases:
Meningitis Pulmonary disease
Found in pigeon & chicken droppings Diagnosis:
India ink test Latex agglutination test for cryptococcal
antigen
India Ink staining of CSF
Polyenes Azoles
Imidazoles Triazoles
Echinocandins
Allylamines Flucytosine Griseofulvin
Polyenes Eg.:
Amphotericin B Nystatin
MOA: Bind to sterols of eukaryotic cell memb→
leakage of cell contents Amphotericin B:
Active against all fungi Leishmania Given parenterally Poor CSF penetration
ADRs: Fever Rigor Nephrotoxicity Hyperkalemia Headache
Azoles Inhibit cyt p450 14α-demethylase
→inhibit fungal cell wall synthesis Active against:
Candida Dermatophytes Aspergillus
Imidazole: Topical: Clotrimazole Systemic: Ketoconazole
Triazoles: Fluconazole: Inactive against invasive
moulds Itraconazole: Inactive against zygomycetes
Echinocandins Capsofungin Inhibit cell wall glucan synthesis
→cell wall lysis Active against:
Candida Aspergillus
Inactive against: Other moulds Cryptococcus
Allylamines
Terbinafine Reduce ergosterol synthesis Active against
dermatophytes Uses:
Skin dermatophyte infection Nail dermatophyte infection
Flucytoscine: Incorporates into fungal mRNA instead of uracil
→ disruption to protein & DNA synthesis Activity:
Cryptococcus Candida
Resistance: Common ADRs:
Bone marrow toxicity Hepatotoxicity
Griseofulvin: MOA unclear Use: Nail infections
Mycotic Diseases of the External Ear
Otomycosis Dermatophytosis Chromoblastomycosis Sporotrichosis
Otomycosis
Defn: Superficial, diffuse, fungal infection of the ear canal
Predisposing condition usually present
Aetiological agents: Aspergillus: (Tropical & Subtropical
regions) Niger Flavus Fumigatus
Candida: (Temperate regions) Albicans Parapsilosis Tropicalis
Penicillium Rhizopus Mixed
Epidemiology
Environment: Warm Humid
Children less commonly affected
Not contagious Predisposing factors:
Seborrhic dermatitis Psoriasis Prolonged use of:
Topical antibiotics Topical corticosteroids
Clinical Manifestations C/C:
Aural fullness Pruritis Discharge
Otoscopy: Debris Erythematous/ oedematous ear
canal A. niger: (Blotting paper)
Mat of fungus Black sporing heads
Chronic infection: Eczematoid change Lichenification
Diagnosis
Clinical Microscopic
examination Culture
Management
Removal of debris Cleaning Antifungal agents:
Local application Gauze packs Mercurochrome & boric
acid
Mycotic diseases of the nose and nasal passages
Entomophthoramycosis Rhinosporidiosis
Entomophthoramycosis
Definition:Chronic localised subcutaneous fungal
infection that originates from nasal mucosa and spreads painlessly to the adjacent subcutaneous tissue of the face
Rare Seen in healthy individuals Severe facial disfigurement C/A: Conidiobolus coronatus
Management
Oral antifungal drugs Treatment continued 1mnth after
lesions have disappeared Surgical resection:
Hastens spread of infection
Rhinosporidiosis
Definition: Uncommon granulomatous infection that affects
nasal mucosa, ocular conjunctiva & other mucosa
Etiology: Rhinosporidium seeberi Fungi: controversial 18S small subunit ribosomal DNA: Mesomycetozoa
In tissues: Thick walled sporangium like structures Endospores
Epidemiology
Geographical distribution: South India Sri Lanka East Africa Central & South America
Natural habitat: Stagnant pools of fresh
water
M>F Age:15-40yrs
Clinical Features
Nasal obstruction Rhinoscopy:
Pink/ Red/ Purple Papular/ Nodular Smooth surfaced Papillomatous/ Proliferative
Diagnosis: HPE:
Large sporangia filled with spores
Thick wall Operculum
Rhinosporidiosis
Management: Surgical excision Cauterization
Outcomes & Complications:
Recurrence
Mycotic Diseases of Paranasal Sinuses
Classification (Based on HPE & C/F):1. Invasive Sinusitis:
1. Active Invasive2. Chronic Invasive3. Chronic granulomatous invasive or
paranasal granuloma
2. Noninvasive Sinusitis3. Allergic Fungal Sinusitis
Invasive Fungal Sinusitis
Diagnosis: Evidence of
sinusitis: Radiographic Nasal endoscopy
Fungal hyphae: HPE
Etiological Agents
Acute fulminant: Rhizopus spss.
R. arrhizus Absidia spss. Rhizomucor spss. Aspergillus spss.
A. flavus A. fumigatus
Fusarium spss. S. apiospermum
Chronic invasive: Alternaria spss. Aspergillus spss. Bipolaris spss. Curvularia spss. Exserohilum spss.
Granulomatous invasive:
A. flavus
Epidemiology Worldwide Adults Immunocompromised children Risk factors:
Prolonged neutropenia Metabolic acidosis Hematological malignancies Haematopoetic stem cell transplant
recipients Diabetics Corticosteroid therapy Deferoxamine treatment HIV infection
Clinical Features Acute Invasive:
Immunocompromised Unilateral facial swelling Unilateral headache Nasal obstruction/ pain Serosanguinous nasal
discharge Necrotic black lesions on:
Hard palate Nasal turbinate
Periorbital/ perinasal swelling Destruction of facial tissue Ptosis Proptosis Ophthalmoplegia Loss of vision
Chronic invasive: Nasal obstruction Chronic sinusitis Thick nasal polyposis Thick purulent mucus Orbital apex syndrome Cavernous sinus thrombosis
Chronic granulomatous:
Nasal obstruction Unilateral facial discomfort Enlarging mass Proptosis
Diagnosis
CT Scan: Acute invasive:
Multiple sinuses Unilateral No air fluid level Thickening of sinus
lining Bone destruction
Chronic invasive: Hyperdense mass Sinus wall erosion
Chronic granulomatous: Opacification of
sinuses Erosion
MRI: Cavernous sinus Cerebral
Local biopsy: HPE Direct microscopy:
KOH mount Culture
Management
Control of underlying host disorders Removal of necrotic & infected
tissue Effective antifungal therapy
Noninvasive Fungal Sinusitis
Fungal ball: Dense mass of fungal
hyphae Aetiological agent:
Aspergillus fumigatus Other Aspergillus spss S. apiospermum Alternaria
Epidemiology: Older age group F>M
Clinical Features Asymptomatic Nasal obstruction Purulent nasal
discharge Cacosmia Facial pain Unilateral symptoms Unusual symptoms:
Fever Cough Proptosis Epistaxis Diplopia Nasal polyp
Diagnosis CT Scan:
Partial/ total opacification Flocculent calcification
Mucopurulent material: HPE:
Dense matted fungal hyphae separate from but adjacent to the mucosa of sinus
No allergic mucin No granulomatous reaction No fungal invasion
Management: Surgical removal No antifungal agents
Outcomes & Complications:
Recurrence: Rare Intracerebral bleed/ infarct Invasive fungal sinusitis
Allergic Fungal Sinusitis Noninvasive
Immunocompetent individuals Chronic rhinosinusitis Criteria for diagnosis:
Chronic rhinosinusitis (CT Scan) Allergic mucin
Clusters of eosinophils Eosinophillic byproducts
Noninvasive fungal elements Type I (IgE mediated)
hypersensitivity Nasal polyposis
Ponikau et al. (1999): 210 pts with chronic rhinosinusitis Fungus in nasal mucus: 202 pts
(96%) Surgical treatment: 101 Allergic mucin: 97 (96%) Fungal elements in HPE: 82 (81%)
Conclusion: AFS- Underdiagnosed disorder
Aetiology: Aspergillus Dematiaceous environmental
moulds: Alternaria Bipolaris Cladosporium Curvularia Drechslera
Epidemiology: Young immunocompetent
adults Relapsing rhinosinusitis Unresponsive to:
Antibiotics Antihistamines Corticosteroids
M=F Atopic Southern United States
Clinical Features h/o Chronic rhinosinusitis U/L nasal polyposis Thick yellow-green mucus Bone necrosis of thin walls of sinus Proptosis DNS to opposite side Pt with nasal polyposis responding
only to oral corticosteroids
Diagnosis CT Scan: Serpiginous opacification of >1 sinus Mucosal thickening Bone erosion No tissue invasion
Microscopic Examination of allergic mucin:
Eosinophils Fungal elements
Histologic examination to r/o invasion Lab tests:
Eosinophilia Total serum IgE Specific IgE against fungal Ags +ve skin prick tests
Fungal cultures
AFS
Management Surgical debridement Adjunctive medical
management: Oral corticosteroids Specific allergen immunotherapy Nasal corticosteroids Antihistamines Antileukotrienes Sinonasal saline lavage
Systemic antifungals: not effective
Mycotic Diseases of the Throat
Candidiasis Histoplasmosis Paracoccidioidomycosi
s Blastomycosis Coccidioidomycosis Cryptococcosis
Candidiasis
Infections caused by organisms of genus Candida
Etiological Agents: C. albicans C. glabrata C. krusei C. tropicalis C. parapsilosis
Epidemiology C. albicans:
Commensal in the mouth of 40% ppl No. ↑es with:
Tobacco smoking Dentures
Host factors: General:
Debilitated pts.: Broad spectrum antibiotics Corticosteroids DM Severe nutritional deficiencies Immunosuppressive diseases eg AIDS
Local: Trauma:
Unhygienic dentures Ill fitting dentures
Tobacco smoking
Clinical Manifestation
Clinical forms: Pseudomembranous Erythematous (or atrophic) Hyperplastic (or
hypertrophic)
Pseudomembranous Pts using steroid inhalers Immunocompromised individuals Neonates Terminally ill pts Lesions:
Raised white Surface of:
Tongue Soft & hard palate Buccal mucosa Tonsils
Confluent plaques Painless
Throat involvement: Severe dysphagia Pseudomembrane wiped off:
Pseudomembranous Candidiasis
Candidiasis
Erythematous Associated with:
Broad spectrum antibiotic treatment
Chronic corticosteroid use HIV
Any part of oral mucosa Lesions:
Flat Red Tongue: depappillated areas
Hyperplastic (Candida leukoplakia)
Lesions undergo malignant transformation
Lesions: Small, palpable, translucent white areas Large, dense, opaque plaques, hard,
rough
Lesions cannot be removed Site:
Inner surface of both cheeks Tongue
Other Candidal Lesions Chronic atrophic
candidiasis: Denture stomatitis Associated with oral prostheses Asymptomatic Soreness Cheilitis
Laryngeal Candidiasis: Hoarseness Dysphagia Stridor Plaques on laryngeal mucosa
Diagnosis: Clinical Microscopy HPE Culture
Management:
Antifungals Topical Systemic
Mycotic Colonization of Tracheo-oesophageal Voice
Prostheses Biofilm formation Invasion of silastic Causative agents:
C. albicans C. glabrata C. krusei C. tropicalis
Results in: Valve failure Device replacement
Local antifungal therapy: inadequate
Metal coating of prostheses
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