1. CHAPTER 14- PARASITIC & FUNGAL INFECTIONS

2. WHY IS THIS IMPORTANT?
Parasitic infections affect billions of people in the world.
Fungal infections are usually opportunistic infections and have increased with the number of immunocompromised individuals.
Parasites can be divided into two groups:
Protozoans – microscopic, single-celled eukaryotes.
Helminths – macroscopic, multicellular worms.

3. SIGNIFICANCE OF PARASITIC INFECTIONS
Parasitic infections are a major problem worldwide.
More than 500 million people are infected with malaria.
More than 2 million (mostly children) die each year from malaria.
Entamoeba are intestinal parasites that infect 10% of the world population.
Trypanosoma parasites infect 16 million people in Latin America each year.

4. SIGNIFICANCE OF PARASITIC INFECTION

5. FUNGAL INFECTIONS
The study of fungi is known as mycology and scientist who study fungi is known is a mycologist
A fungus is a member of a large group of eukaryotic organisms
Microorganisms such as yeasts and molds, as well as the more familiar mushrooms
Over 60,000 species of fungi are known
Fungi are important for the environment.
They are normally harmless to humans
Fungi can be opportunistic pathogens.

6. Structure
The main body of most fungi is made up of fine, branching, usually colourless threads called hyphae ( PG 310)
Several of these these hyphae, all intertwining to make up a tangled web called the mycelium
Most fungi are multinucleate and multicellular organisms with cross wall called septa or aseptate (coenocytic)
Yeasts are unicellular
One major difference is that most fungi have cell walls that contain chitin, unlike the cell walls of plants, which contain cellulose

7. Single Hyphae

8. Reproduction
Life cycle involves the fusion of hyphae from two individuals (Male & Feamle
Each parent hyphae has haploid nuclei
The fusion of hyphae is called plasmogamy.
The fused hyphae containing haploid nuclei from two individuals is heterokaryotic.
In some cases, plasmogamy results in cells with one nucleus from each individual. This condition is called dikaryotic.
Two nuclei that originated from different individuals fuse to form a diploid zygote.
Meiosis then produces either four haploid nuclei or four haploid cells.

9. YEASTS AND MOLDS Molds - multicellular Yeasts - unicellular
The simplest form of growth is budding.
Buds are called blastoconidia.
Seen in yeasts.

10. ..Reproduction in yeast

11. YEASTS AND MOLDS
© CDC/ Dr. Edwin P. Ewing, Jr.

12. The life cycle of Rhizopus stolonifera ( bread mold)..

13. ….Reproductive structures in Breadmold
….Reproductive structures in Breadmold .

14. Classification of Fungi
By Reproductive Structures (PG 312)
Oomycetes
Water Molds
Motile sexual spores
Example: Potato blight Phytophthora

15. …..Classification of Fungi
Zygomycetes
Unenclosed zygospores produced at ends of hyphae
Example: Black bread mold Rhizopus
Ascomycetes
Ascospores are enclosed in asci (sac-like structures) at the ends of hyphae or yeasts
Examples: Penicillium, Saccharomyces

16. ..Zygomycota
Conjugation Fungi

17. …..Classification of Fungi
Basidiomycetes
Basidiospores are produced on a club-shaped structure called a basidium
Example: Mushrooms, Cryptococcus
Deuteromycetes
“Imperfect fungi”
No sexual stage is known for these fungi
Many parasitic fungi fall into this class
Examples: Candida, Epidermophyton

18. CLASSIFICATION OF PATHOGENIC FUNGI
Fungal diseases are classified into 4 groups:
Superficial mycoses
Mucocutaneous mycoses
Subcutaneous mycoses
Deep mycoses

19. SUPERFICIAL MYCOSES
Fungal infections that do not involve a tissue response:
Piedra – colonization of the hair shaft causing black or white nodules
Tinea nigra – brown or black superficial skin lesions
Tinea capitis – folliculitis on the scalp and eyebrows

20. …SUPERFICIAL MYCOSES Favus – destruction of the hair follicle.
Pityriasis – dermatitis characterized by redness of the skin and itching:
Caused by hypersensitivity reactions to fungi normally found on skin
Mostly seen in immunocompromised patients.

21. CUTANEOUS AND MUCOCUTANEOUS MYCOSES
Associated with:
Skin
Eyes
Sinuses
Oropharynx and external ears
Vagina

22. …CUTANEOUS AND MUCOCUTANEOUS MYCOSES
Ringworm – skin lesions characterized by red margins, scales and itching:
Classified based on location of infection
Tinea pedis – on the feet or between the toes
Tinea corporis – between the fingers, in wrinkles on the palms
Tinea cruses – lesions on the hairy skin around the genitalia
Tinea capitis – scalp and eyebrows
Onychomycosis – chronic infection of the nail bed
Commonly seen in toes
Hyperkeratosis – extended scaly areas on the hands and feet

23. ..CUTANEOUS AND MUCOCUTANEOUS MYCOSES

24. …CUTANEOUS AND MUCOCUTANEOUS MYCOSES
Mucocutaneous candidiasis – colonization of the mucous membranes
Caused by the yeast Candida albicans
Often associated with a loss of immunocompetence
Thrush – fungal growth in the oral cavity
An indicator of immunodeficiency.
Vulvovaginitis – fungal growth in the vaginal canal
Can be associated with a hormonal imbalance

25. SUBCUTANEOUS MYCOSES
Localized primary infections of subcutaneous tissue:
Can cause the development of cysts and granulomas.
Provoke an innate immune response - eosinophilia.

26. …SUBCUTANEOUS MYCOSES
There are several types:
Sporotrichosis – traumatic implantation of fungal organisms
Paranasal conidiobolae mycoses – infection of the paranasal sinuses
Causes the formation of granulomas.
Zygomatic rhinitis – fungus invades tissue through arteries
Causes thrombosis
Can involve the CNS.

27. DEEP MYCOSES
Deep mycoses Usually seen in immunosuppressed patients with:
AIDS
Cancer
Diabetes
Can be acquired by:
Inhalation of fungi or fungal spores
Use of contaminated medical equipment
Deep mycoses can cause a systemic infection – disseminated mycoses
Can spread to the skin

28. ..DEEP MYCOSES

29. ..DEEP MYCOSES Coccidiomycoses – caused by genus Coccidioides
Primary respiratory infection
Leads to fever, erythremia, and bronchial pneumonia
Usually resolves spontaneously due to immune defense
Some cases are fatal

30. …DEEP MYCOSES Histoplasmosis – caused by Histoplasma capsulatum
Often associated with immunodeficiency
Causes the formation of granulomas
Can necrotize and become calcified
If disseminated, histoplasmosis can be fatal.

31. ..DEEP MYCOSES
© CDC/Susan Lindsley, VD

32. …DEEP MYCOSES Aspergillosis – caused by several species of Aspergillus
Associated with immunodeficiency
Can be invasive and disseminate to the blood and lungs
Causes acute pneumonia
Mortality is very high.
Death can occur in a matter of weeks.

33. Common Fungal Diseases
Additional Information to read:
Candidiasis
Dermatomycoses
Respiratory Fungal Infections

34. Candidiasis Cause: Candida albicans
Dimorphic fungus of the class Deuteromycetes
Grows as yeast or pseudohyphae
Spread by contact; often part of normal flora
Opportunistic infections common
Vulvovaginitis
Oral candidiasis (thrush)
Intestinal candidiasis

35. Dermatomycoses
Dermatomycoses are any fungal infection of the skin or hair.
Caused by many different species and are generally named after the infected area rather than the species that causes it.
Dermatomycoses are one of the most frequent sources of lesions on the skin.

36. …Dermatomycoses Cause: Several genera of dermatophytic fungi
Trichophyton, an ascomycete
Microsporum, an ascomycete
Epidermophyton, a deuteromycete
Grow on skin, hair, nails
Transmitted by contact with infected persons or animals

37. …Dermatomycoses
Tinea is a fungus that can grow on your skin, hair or nails.
As it grows, it spreads out in a circle, leaving normal-looking skin in the middle- look like a ring.
At the edge of the ring, the skin is lifted up by the irritation and looks red and scaly.
To some people, the infection looks like a worm is under the skin.
Because of the way it looks, tinea infection is often called "ringworm." no worm under the skin!!
Pictures!!!!

38. ….Dermatomycoses
Tinea infections: Red, scaly or blister-like lesions; often a raised red ring; “ringworm”
Tinea pedis
Tinea corporis
Tinea capitis
Tinea favosa
Tinea barbae
Tinea cruris
Tinea unguium

39. Respiratory Fungal Infections
Cryptococcosis
Cryptococcus neoformans
A yeast of class Basidiomycetes
Soil; esp. contaminated with bird droppings
Airborne to humans
Gelatinous capsules resist phagocytosis
Respiratory tract infections
Occasional systemic infections involving brain & meninges

40. …. Respiratory Fungal Infections
Histoplasmosis
Histoplasma capsulatum, an ascomycete
Airborne infection
Transmitted by inhalation of spores in contaminated spores
Associated with chicken & bat droppings
Respiratory tract symptoms; fever, headache, cough, chest pains

41. ….Respiratory Fungal Infections
Blastomycosis
Blastomyces dermatitidis, an ascomycete
Associated with dusty soil & bird droppings
Skin transmission: via cuts & abrasions
Raised, wart-like lesions
Airborne transmission: via inhalation of spores
Respiratory tract symptoms
Occasional internal infections with high fatality rate

42. References http://www.microbiologybytes.com/introduction/myc2.html
Microbiology, A clinical Approach -Danielle Moszyk-Strelkauskas-Garland Science 2010
2261/home.html
Lecture PowerPoints Microbiology Principles and Exploration 7th edt. J G Black ; J Wiley Pub.