INSTITUTE OF HEALTH TECHNOLOGY, DHAKADepartment of Laboratory Medicine

BSc in Health Technology (Laboratory)- 1st Year

MYCOLOGY Lecture No. 7.3 (Opportunistic Mycoses -Aspergillosis)

By

Sk. MIZANUR RAHMANLecturer, Mycology

MS in Biotechnology & Genetic Engineering (UODA)MS in Microbiology (SU)

AspergillosisAspergillosis is a spectrum of diseases of humans and animals caused by members of the genus Aspergillus. These include (1) mycotoxicosis due to ingestion of contaminated foods; (2) allergy and sequelae to the presence of conidia or transient growth of the organism in body orifices; (3) colonization without extension in preformed cavities and debilitated tissues; (4) invasive, inflammatory, granulomatous, necrotizing disease of lungs, and other organs; and rarely (5) systemic and fatal disseminated disease. The type of disease and severity depends upon the physiologic state of the host and the species of Aspergillus involved.Distribution: World-wide.Aetiological Agents: Aspergillus fumigatus, A. flavus, A. niger, A. nidulans and A. terreus.

CLASSIFICATION OF ASPERGILLOSIS

Persistence without disease - colonisation of the airways or nose/sinuses

Airways/nasal exposure to airborne Aspergillus

Invasive aspergillosis• Acute (<1 month course)• Subacute/chronic necrotising (1-3 months)

Chronic aspergillosis (>3 months)• Chronic cavitary pulmonary• Aspergilloma of lung• Chronic fibrosing pulmonary• Chronic invasive sinusitis • Maxillary (sinus) aspergilloma

Allergic• Allergic bronchopulmonary (ABPA)• Extrinsic allergic (broncho)alveolitis (EAA)• Asthma with fungal sensitisation• Allergic Aspergillus sinusitis (eosinophilic fungal rhinosinusitis)

Aspergillosis infection 1. Allergic aspergillosis AsthmaAllergic bronchopulmonary aspergillosis (ABPA)IgE antibodies present. In ABPA also 1gG

2. Colonizing aspergillosis (ASpergilloma=Aspergillus fungus ball)

Pulmonary aspergilloma

diagnoses include: cough , hemoptysis, variable fever

CXR will show coin-like mass in the lung

3. Invasive aspergillosis-pulmonary

Sings: cough, hemoptysis, fever, Penomonia, leukocytosis

Lab investigation (direct microscopy and culture) may be negative especially if specimen is noninvasive like sputum

4. Aspergillus sinusitis

Nasal polyps-sinusitis-eye-cranium (rhinocerebral)

The most common cause is Aspergillus flavas (also other fungi can cause sinusitis)

Aspergillosis infection

5. Eye infection,, corneal ulcer-endopthalamitis

6. Ear infection,,otitis externa-otitis media

7. Nail and skin infection

8. Toxicosis due to ingestion of aflatoxin

9. Disseminated form-rare, in debilitated patients

Fungus ball or Pulmonary Aspergilloma which is characteristically seen in the old cavities of TB patients. This is easily recognized by x-ray, because the lesion (actually a colony of mold growing in the cavity) is shaped like a half-moon (semi-lunar growth). The patients may cough up the fungus elements because the organism frequently invades the bronchus. Chains of conidia can sometimes be seen in the sputum.

Aspergillosis infection

Aspergillus

Conidiophore

Swollen apex of conidiophore (vesicle)

Conidia

Supporting cell (branch or metulae)Conidiogenous cells (phialides)

Basal part of conidiophore (foot cell)

Culture: •Aspergilli require 1-3 weeks for growth. •The colony begins as a dense white mycelium which later assumes a variety of colors, according to species, based on the color of the conidia. •The hyphae are branching and septate.• Species differentiation is based on the formation of spores as well as their color, shape and texture. Histopathology: •The septate hyphae are wide and form dichotomous branching, i.e., a single hypha branches into two even hyphae, and then the mycelium continuesbranching in this fashion

Diagnosis

Serology: •There is an excellent serological test for aspergillosis which is an Immunodiffusion test ( ELISA). •There may be 1 to 5 precipitin bands. Three or more bands usually indicate increasingly severity of the disease. i.e., tissue invasion.( detection of IgG and IgE)

Diagnosis

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Grocott’s methenamine silver (GMS) stained tissue section of lung showing fungal balls of hyphae of Aspergillus fumigatus.

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Grocott’s methenamine silver (GMS) stained tissue section of lung showing dichotomously branched, septate hyphae of Aspergillus fumigatus.

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Grocott’s methenamine silver (GMS) stained tissue sections showing Aspergillus fumigatus in lung tissue, note conidial heads forming in an alveolus.

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Grocott’s methenamine silver (GMS) stained tissue sections showing Aspergillus fumigatus in lung tissue, note conidial heads forming in an alveolus.

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Aspergillus fumigatus on Czapek dox agar showing typical blue-green surface pigmentation with a suede-like surface consisting of a dense felt of conidiophores.

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Aspergillus niger on Czapek dox agar. Colonies consist of a compact white or yellow basal felt covered by a dense layer of dark-brown to black conidial heads.

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Aspergillus flavus on Czapek dox agar. Colonies are granular, flat, often with radial grooves, yellow at first but quickly becoming bright to dark yellow-green with age.

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Immunodiffusion test showing precipitins against Aspergillus.