This document provides information on fungal infections and actinomycosis. It describes common endemic and opportunistic fungal infections like Candida, Aspergillus, Mucor, and Cryptococcus that typically infect immunocompromised individuals. Superficial fungal infections involve the skin, hair and nails, while deep infections spread systemically. Specific fungal infections discussed include candidiasis, aspergillosis, mucormycosis, and madura foot. Actinomycosis is also covered, which is caused by bacteria like Nocardia and Actinomyces. Pneumocystis jirovecii pneumonia is an opportunistic infection in AIDS patients. Diagnosis involves microscopic

1. Fungal Infection and Actinomycosis
Lecture-44

2. Learning Objectives
Enlist common endemic and opportunistic fungal infections
Describe the tissue reaction against fungal infection

3. Types of Fungi
Endemic fungi
Limited to particular geographic regions (e.g., Coccidioides in southwestern
United States, Histoplasma capsulatum in the Ohio River Valley)
Opportunistic fungi
Candida, Aspergillus, Mucor, and Cryptococcus , colonize normal human
epithelia but in immunodeficient, give rise to life-threatening invasive
infections characterized by tissue necrosis, hemorrhage, vascular occlusion,
and with little or no inflammatory response
AIDS patients often infected by opportunistic fungus Pneumocystis
jiroveci (Pneumocystis carinii)
3

4. Types of Fungal Infections
Superficial fungal infections
Dermatophytes cause superficial infections; involve skin, hair, and nails
Skin infection called tinea e.g tinea pedis (athlete's foot) and tinea
capitis scalp ringworm
Invade subcutaneous tissue, causes abscess formation or granulomatous
reaction and sometimes mycetomas
Deep fungal infections
Spread systemically and invade tissues, destroying vital organs in
immunocompromised hosts, but usually resolve or remain latent in normal
hosts

5. Candidiasis
Infection caused by Candida albicans which
exit in yeast and pseudohyphae form
Characteristically candida infection of oral
cavity produces whitish lesions and in vagina
causes milky white vaginal discharge
Systemic candida infection occurs in
immunocomprised leads to life-threatening
invasive infections characterized by tissue
necrosis, hemorrhage, and vascular occlusion
Stain positive with PAS and GMS

6. Aspergillosis
Infection by fungus aspergillus
Aspergilloma (fungus ball) seen
in; paranasal sinus, lung and
some time intracranial involving
brain
Fungus is angioinvasive
Septate hyphae, branching at
acute angles of about 45
Stain black with GMS stain
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7. Mucormycosis
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Infection caused by mucor fungus
Broad non-septate hyphae
Frequently infects sinuses, oral
cavity, brain and lung
Angioinvasive; hyphae growing in
and around blood vessels causing
ischemia

8. Madura Foot
Mycetoma, an uncommon chronic infection of skin and subcutaneous
tissues in tropical countries is caused either by;
True fungi (eumycetoma) 40%
Filamentous bacteria (actinomycetoma) 60%
The most common site of occurrence is foot the synonym “Madura foot”,
hand is the next
Bare foot repeated minor trauma or penetrating injury provides a portal of
entry for the organism
Since treatment of two etiologies is entirely different, a definite diagnosis is
mandatory

9. Madura Foot
Grossly
Indurated skin with central ulceration surrounded by
granulation tissue and purulent discharge admixed with;
Black granules in eumycetoma
Yellow sulphur granules in actinomycosis
Microscopy
Characteristic granules or colonies of filamentous
structures surrounded by suppurative granulomas
composed of neutrophilic infiltrate, palisading
histiocytes and occasional multinucleated giant cells
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10. Differential Diagnosis of Madura Foot
Eumycetoma; thick club shaped Actinomycetoma; thin filaments
GMS+ Gram+

11. Actinomycetae
Bacteria normally found in oral cavity, nose,
throat and GIT, two common types;
Nocardia asteroides -Nocardiosis
Actinomyces israelii - Actinomycosis
Predisposing conditions:
Recent dental surgery
Poor oral hygiene with Periodontal disease
Radiation therapy
Fracture jaw bones
After appendectomy
Use of intrauterine devices
Actinomycosis: characterized by
the formation of painful abscesses in
oral cavity , lungs, GIT or
subcutaneous tissue
Infection depends on other bacteria
to help in invasion of tissue
Abscesses grow larger , over
months and may penetrate
surrounding bone, muscle and skin
forming sinuses
Sinus discharge often contains
characteristic Sulphur granules

12. Pneumocystis carinii (jirovecii)
Microscopically, alveoli filled with granular pink
exudate in this case of Pneumocystis carinii
(jirovecii) pneumonia (PCP)
At higher magnification, the granular pink
exudate consists of edema fluid,
protein, Pneumocystis organisms, and dead
macrophages
GMS positive ; The cyst wall is stained, and
the organisms appear as crushed ping-pong
balls, or crescent shapes, or folded spheres,
or flattened beach balls, or deflated tennis
balls

13. Cryptococcus neoformans
Cryptococcal infection of the lung shows
numerous organisms having a large mucoid
capsule surrounded by a clear zone around
a faint round nucleus
Cryptococci stained black with GMS to
reveal the nuclei in a case of cryptococcal
meningitis

14. Home Assignment
Q1. What is the difference among the hyphae of candida, aspergillus,
and mucor explain with the help of diagram?
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15. References
Robbins Basic Pathology, 10th Edition (2017), By: Kumar, Abbas, Aster
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