Fungal infections and Actinomycosis

1. Lecture 7

2. Learning Objectives
1. Types of common human fungal infections
2. Risk factors of Candida infection
3. Types of candidiasis and its complications
4. Aetiology and epidemiology of actinomycosis with subsequent
complications
5. Morphology of madura foot
6. Enlist common bacterial & protozoal infections

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
• Candida exit in yeast and pseudohyphae form
• Characteristically candida infection in;
Oral cavity - whitish lesions
Vagina- milky white vaginal discharge
• Systemic candida infection occurs in immunocomprised leads to
life-threatening invasive infections characterized by tissue
necrosis, hemorrhage, and vascular occlusion

6. Oral Thrush

7. 7
Candidiasis of Esophagus

8. Candida albicans
GMS positive PAS positive

9. 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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10. Mucormycosis
3/4/2018
• Fungal infection caused by
Mucor having non-septate
hyphae
• Frequently infects sinuses,
oral cavity, brain and lung
• Angioinvasive, hyphae
growing in and around blood
vessels causing ischemia

11. Actinomycetae
Bacteria normally found in the oral cavity, nose, throat and GIT, two common types;
a. Nocardia asteroides -Nocardiosis
b. Actinomyces israelii –Actinomycosis
Predisposing conditions:
I. Recent dental surgery
II. Poor oral hygiene with Periodontal disease
III. Radiation therapy
IV. Fracture jaw bones
V. After appendectomy
VI. Use of intrauterine devices

12. Actinomycosis
• Characterized by the formation of painful abscesses in oral
cavity , lungs, gastrointestinal tract or subcutaneous tissue
• Actinomycosis 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
• Pus leaking from the sinus often contains characteristic
granules (sulphur granules)

13. Madura Foot
• Mycetoma, an uncommon chronic infection of skin and subcutaneous
tissues in tropical countries is caused either by;
a. True fungi (eumycetoma) 40%
b. 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

14. Madura Foot
Grossly
Indurated skin with central ulceration surrounded by granulation tissue and
purulent discharge admixed with black granules in eumycetoma and yellow
sulphur granules in actinomycosis
Microscopy
Characteristic granules or colonies of filamentous structures surrounded by
suppurative granulomas composed of neutrophilic infiltrate, palisading
histiocytes along with occasional multinucleated giant cells,
Thin filaments in actinomycetoma and thick club shaped in eumycetoma
3/4/2018

15. Madura Foot
3/4/2018

16. Microscopy
Eumycetoma Actinomycosis
3/4/2018
Fungal stain Gram Positive

17. Diagnosis
• Clinically black granule in eumycetoma and yellow sulphur
granules in actinomycosis
• Crush smears cytology of black granules in eumycetoma and
yellow sulphur granules in actinomycetoma
• Biopsy and culture; actinomycetoma (Gram positive) and
eumycetoma (Gram negative) which is identified by fungal
stains (GMS) and confirm by fungal culture

18. Bacterial Coccal Infections
Infections by Gram positive cocci
Staphylococcus aureus, S. epidermidis; Abscess, cellulitis, pneumonia,
septicemia
Streptococcus pyogenes; β-hemolytic Upper respiratory tract infection,
erysipelas, scarlet fever, septicemia
Streptococcus pneumoniae ; Lobar pneumonia, meningitis
Infections by Gram negative cocci
Neisseria meningitidis; Cerebrospinal meningitis
Neisseria gonorrhoeae ; Gonorrhea

19. Bacterial Bacillary Infections
Infections by Gram-negative bacilli
Escherichia coli, Klebsiella pneumoniae Enterobacter, Proteus and
Pseudomonas; urinary tract infection, wound infection, abscess,
pneumonia, septicemia, endotoxemia, endocarditis
Haemophilus influenzae; meningitis, respiratory tract infections
Chlamydia trachomatis; ectopic pregnancy,
female sterility, conjunctivitis and corneal opacities
Infections by Gram-positive bacilli
Mycoplasma pneumoniae; atypical pneumonia

20. Protozoa
Intracellularly in many cell types
Plasmodium; in erythrocytes causes malaria
Leishmania; in macrophages causes on healing wound, bone marrow
infection
Extracellularly in the urogenital system, intestine, or blood
Trichomonas vaginalis; colonize vagina and male urethra
Entamoeba histolytica; large intestine (dysentery), liver (abscess)
Giardia lamblia; small intestine (diarrhea)
Toxoplasma gondii; lymphadenopathy, cysts in brain ,eye and muscle

21. Home Assignment
Q1. What is the difference among the hyphae of
candida, aspergillus, and mucor?
3/4/2018

22. Learning Outcomes
• Know the common human fungal infections
• Describe the types, mode of transmission and pathogenesis of the
Candida albicans
• Know the aetiology, pathogenesis and complications of actinomycosis
• Know the aetiology and epidemiology of madura foot
• Identify common bacterial and protozoal infections

23. References
• Reading : Robbins Basic Pathology, 9th Edition (2013), By: Kumar,
Abbas, Aster
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