Fungi are eukaryotic microorganisms which are heterotrophic and essentially aerobic with limited anaerobic capabilities. Fungi synthesize lysine by the L-αadipic acid biosynthetic pathway. They possess chitinous cell walls, plasma membranes containing ergosterol, 80SrRNA and microtubules composed of tubulin. Fungi grow as yeasts, molds (filamentous) or a combination of both (i.e. dimorphism).

1. Fungi
Fungi are eukaryotic
microorganisms which are
heterotrophic and essentially
aerobic with limited
anaerobic capabilities. Fungi
synthesize lysine by the L-
αadipic acid biosynthetic
pathway. They possess
chitinous cell walls, plasma
membranes containing
ergosterol, 80SrRNA and
microtubules composed of
tubulin. Fungi grow as yeasts,
molds (filamentous) or a
combination of both (i.e.
dimorphism).

2. Common features of fungi
• Fungi are not plants or animals, they form a separate
group of higher organisms, distinct from both plants and
animals, which differ from other groups of organisms in
several major respects:
1. Fungal cells are encased within a rigid cell wall, mostly
composed of chitin and glucan.
• These features contrast with animals, which have no cell walls,
and plants, which have cellulose as the major cell wall
component.

3. Common features of fungi
2. Fungi are heterotrophic.
• This means that they are lacking in chlorophyll and cannot
make their organic food as plants can, through
photosynthesis.
• Fungi live embedded in a food source or medium, and
obtain their nourishment by secreting enzymes for
external digestion and by absorbing the nutrients that are
released from the medium.
• Some live on humans e.g. the cause ringworm infections.
Some live on insects, or plants.
3. Fungi are simpler in structure
• There is no division of cells into organs or tissues.

4. Common features of fungi
• Fungi are heterotrophic and essentially aerobic, with
limited anaerobic capabilities
• Fungi possess chitinous cell walls, plasma
membranes containing ergosterol, 80S rRNA, and
microtubules composed of tubulin.

5. Structure
Fungi
Yeast Filamentous Dimorphic
Yeasts are
single-celled
forms that
reproduce by
budding
Also called as
molds, form
multicellular
hyphae
Dimorphic
fungi grow as
yeasts or
spherules in
vivo and in
vitro at 37°C,
but as molds at
25°C.

6. Yeast: Candida
• Yeasts are fungi that grow as solitary cells that
reproduce by budding
• Candidiasis is a fungal infection due to any type of
Candida (a type of yeast).
• When it affects the mouth, it is commonly called
thrush
• When it affects the vagina, it is commonly called a
yeast infection
• More than 20 types of Candida can cause infection
with Candida albicans being the most common

7. 3 types
Mucosal candidiasis
• The mucosal surfaces primarily affected by
candidiasis are the oral cavity, esophagus, angles of
the mouth, and genitals (causing vulvovaginitis in
females, balanitis in males)
Cutaneous candidiasis
• Candidiasis on skin, nail and hair. Keratinase is
synthesized by fungus that mobilizes keratin

8. 3 types
Systemic candidiasis
• includes a spectrum of yeast infections caused by
different species of Candida.
• It is a serious infection that can affect the blood, heart,
brain, eyes, bones, or other parts of the body.
• most common form of this is when Candida enters the
bloodstream - candidemia.
• Signs of candidemia : fever and chills
• Diagnosis can be difficult, especially when the Candida
is not found in the bloodstream.
• Treatment usually includes consists of oral or
intravenous (IV) antifungal medications

9. Signs and symptoms
• In healthy persons, candidiasis is usually a localized infection of the
skin, fingernails or toenails, or mucosal membranes, including the
oral cavity and pharynx, esophagus, and the genitalia
• less commonly in healthy individuals, the gastrointestinal tract,
urinary tract, and respiratory tract are sites of candida infection.
• In immunocompromised individuals, Candida infections in the
esophagus occur more frequently and have a higher potential of
becoming systemic, causing a much more serious condition, a
fungemia called candidemia

10. Signs and symptoms
vaginal yeast infection
• vaginal itching
• swelling around the vagina
• burning during urination or sex
• pain during sex
• soreness
• redness
• rash
• vaginal discharge
Candidiasis of skin
• Rash
• redness and intense itching.
• become cracked and sore.
• Blisters and pustules may also
occur.
• Candida can also cause
infections in the nails, edges of
the nails, and corners of the
mouth.

11. Signs and symptoms
Oropharyngeal or mucosal
• Creamy white lesions on your
tongue, inner cheeks, and on the
roof of your mouth, gums and
tonsils
• Slightly raised lesions with a
cottage cheese-like appearance
• Redness, burning or soreness that
may be severe enough to cause
difficulty eating or swallowing
• Slight bleeding if the lesions are
rubbed or scraped
• Cracking and redness at the
corners of your mouth
• A cottony feeling in your mouth
• Loss of taste
• Redness, irritation and pain under
dentures (denture stomatitis)
• HIV/AIDS - Candida esophagitis

12. Diagnosis
• done either via microscopic examination or culturing.
For identification by light microscopy
• a scraping or swab of the affected area is placed on a
microscope slide. A single drop of 10% potassium
hydroxide (KOH) solution is then added to the specimen.
The KOH dissolves the skin cells, but leaves the Candida
cells intact, permitting visualization of pseudohyphae and
budding yeast cells typical of many Candida species.

13. Diagnosis
For the culturing method
• a sterile swab is rubbed on the infected skin surface.
The swab is then streaked on a culture medium.
• The culture is incubated at 37 °C for several days.
• The characteristics (such as morphology and colour)
of the colonies may allow initial diagnosis of the
organism causing disease symptoms

14. Diagnosis

15. Treatment
• Clotrimazole
• Nystatin
• Fluconazole
• Voriconazole
• amphotericin B
• echinocandins.
• Intravenous fluconazole are
commonly used to treat
immunocompromised or
critically ill individuals.
Candidiasis is treated with antifungal medications

16. Filamentous fungi
Aspergillosis
• Infections caused by Aspergilli spp.
• ubiquitous in nature and play a significant role in the
degradation of plant material as in composting.
• rarely infect a normal host.
• Aspergillus fumigatus
• Aspergillus niger
• Aspergillus flavus

17. Symptoms
• Symptoms may vary from mild respiratory distress to alveolar
fibrosis.
• disseminate through the blood stream to cause widespread organ
damage.
• Symptoms include fever, chills, shock, delirium, seizures and blood
clots. The person may develop kidney failure, liver failure (causing
jaundice), and breathing difficulties.
• Fungus ball which is characteristically seen in the old cavities of TB
patients.
• 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.

18. Diagnosis and treatment
• Chest X ray or CT Scan
• Microscopy
• Culture of fungus
Serology
• There is an excellent serological test for aspergillosis which is an
Immunodiffusion test. There may be 1 to 5 precipitin bands. Three or more
bands usually indicate increasingly severity of the disease. i.e., tissue
invasion.
Treatment
• Voriconazole and Amphotericin B.

19. Dimorphic fungi
Blastomycosis
• Caused by dimorphic Blastomyces dermatitidis
• survives in soil that contains organic debris and infects people
collecting firewood, tearing down old buildings or engaged in
other outdoor activities which disrupt the soil.
• a chronic granulomatous disease
• pulmonary and skin involvement is the most common,
frequently affects bone, prostate and other organs

20. Blastomycosis: symptoms
• The patient who presents with a complaint of respiratory
symptoms will frequently remark about loss of appetite,
loss of weight, fever, productive cough, and night sweats.
• an acute illness resembling bacterial pneumonia, with
symptoms of high fever, chills, a productive cough, and
pleuritic chest pain
• skin lesions

21. Blastomycosis: Diagnosis
• X-ray
• Culture: A culture of B. dermatitidis takes 7-10days to
grow at 37 degrees C
• Immunodiffusion test (precipitin). This requires 2 to 3
weeks to become positive
• Enzyme Immunoassay (EIA).

22. Blastomycosis: Treatment
• Amphotericin B remains is the drug of choice and
must be administered intravenously for several
weeks.
• Itraconazole is also being used in mild cases.
• Voriconazole is showing promise.

23. Fungal Eye Infections
Fungal infections can affect different parts of the eye.
• Keratitis is an infection of the clear, front layer of the eye (the
cornea).
• Endophthalmitis is an infection of the inside of the eye (the vitreous
and/or aqueous humor). There are two types of endophthalmitis:
exogenous and endogenous. Exogenous fungal endophthalmitis
occurs after fungal spores enter the eye from an external source.
Endogenous endophthalmitis occurs when a bloodstream infection
(for example, candidemia) spreads to one or both eyes.

24. Types of fungi that cause eye infections
Many of different types of fungi can cause eye infections.
1. Fusarium – a fungus that lives in the environment,
especially in soil and on plants
2. Aspergillus – a common fungus that lives in indoor and
outdoor environments
3. Candida – a type of yeast that normally lives on human
skin and on the protective lining inside the body called the
mucous membrane

25. Diagnosis and Treatment
• Microscope, cultured, Polymerase chain reaction
(PCR) and confocal microscopy
• Possible forms of treatment for fungal eye infections
include:
• Antifungal eye drops
• Antifungal medication given as a pill or through a vein
• Antifungal medication injected directly into the eye
• Eye surgery