number 19

Done by اميعمرس

Corrected by حسام أبو عوض

Doctor حامد الزعبي

Fungal infections

- Fungal infections are infections caused by fungi, a type of

microorganisms.

Which sites are mostly affected?

- Mainly, the Skin and subcutaneous tissues are affected, systemic infections

are not common.

Throughout this lecture, we will be discussing the Superficial, Cutaneous &

Subcutaneous fungal infections and the fungi which cause each one of them.

Superficial Infections

➢ Mainly caused by: Malassezia.

Malassezia: a Lipophilic yeast that is round in shape. It is a Normal commensal

of the skin (normal flora). It Can cause skin infections and catheter associated

infections (mainly skin infection in immunocompetent patients & catheter

associated infections in immunocopromised patients).

Immunocompetent vs immunocompromised

- An Immunocompromised patient is (immunology) the one with an

impaired immune system due to a disease or a treatment, while an

immunocompetent patient has a normally functioning immune system.

Diseases caused by Malassezia

- Pityriasis versicolor or Tinea versicolor: A fungal infection characterized

by skin eruption on the trunk and proximal extremities.

- Located mainly on the stratum corneum of the skin “ the outermost

layer of the epidermis”.

- Trunk and proximal limbs are also affected.

Caused mainly by: Malassezia furfur and Malassezia globose

The Classical Diagnostic Situation

→ The disease is common in the tropics and is precipitated by sun exposure

(usually occur after the patient gets exposed to sunlight).

Patches may be white, pink, red or brown and can be lighter or

darker than the skin around them; Carboxylic acid, which is produced by

the yeast, causes depigmentation, either hypo OR hyper – pigmentation.

When the patient arrives to the clinic, what are the main features to be

noticed?

• Asymptomatic.

• Non-itchy macules (at the level of the skin,

not elevated).

• Hypo or hyper pigmented patches.

Diagnosis

→ We can use either microscopic or non-microscopic techniques (we can also

consider the patient’s history, e.g. have they gone to the beach recently?)

Non-Microscopic

How to make sure that it is Malassezia?

- Physicians & dermatologists often use a technique to ensure whether it is

M. furfur or not, they use the Wood ultra-violet lamp test, here M. furfur

appears in a light pale greenish colour.

A Wood lamp examination: is a test that uses ultraviolet (UV) light to look at

the skin closely.

Microscopical

How is it performed?

- Skin scraping → Ink → KOH staining.

How does it appear?

- Thick septate* hyphae** and clusters of budding yeast

cells (Spaghetti and meatballs spores and hyphae) →

which is a special appearance for Malassezia.

*septate: divided to septums.

**hyphae: thread-like, filamentous structures of fungi.

Treatment

Usually not needed, however the patient may ask for it for cosmetic purposes.

- Topical azoles (cream or a shampoo) for 2 weeks.

- In severe cases use oral azoles.

- Recurrence is common.

Seborrheic dermatitis (االكزيمة الدهنية)

- This is another disease that can be caused by Malassezia.

- Skin hyperproliferation with dandruff (قشرة) is the mildest manifestation.

- In more severe cases, lesions are red and covered with greasy scales, hair

loss is seen and an itchy scalp is common.

Treatment

Azoles.

We have finished the first group, superficial mycosis.

Take a five-minute break then let’s continue …

I said five minutes -__-

Cutaneous Mycosis

- Caused by: Dermatophytes [filamentous fungi ( خيوط فطرية) /moulds]

- This includes 3 genera

Microsporum → affects hair and skin.

Epidermophyton → skin and nail.

Trichophyton→ hair, nail and skin.

These fungi affect the keratinized tissues such as skin, hair & nails → they are

thought to have keratinase to disrupt keratin at this site of the body.

Note: Infection is usually not spread to deeper tissues.

How is it transmitted?

1- Man to man: by direct contact, skin contact (Anthrophilic) or by the usage

of the personal belongings of an already infected individual.

2- Animals e.g. dogs and cats (Zoophilic).

3- Soil (Geophilic).

** Heat and humidity enhance the infection.

They are also classified according to the site of infection

Site | Disease

Toes → Tinea pedis or Athletic foot

Body (mainly trunk) → Tinea corporis

Groin area→ Tinea cruris

Head→ tinea capitis

Nails→ Tinea unguinum

Clinically

➢ Red, itchy, scaly rash (dandruff in the middle), ring like with an elevated

inflamed border on the body or groin.

➢ Scaling and hair loss leaving black dots, if it is in the head.

➢ White and opaque / yellow, thickened & broken nails.

Differential diagnosis

- What is a differential diagnosis? - Distinguishing a particular disease or condition from others that present similar

symptoms.

→ So, cutaneous mycosis is usually miss-diagnosed with one of the following;

due to similar symptoms and manifestations.

→ Eczema, psoriasis, impetigo, alopecia, drug reactions.

Diagnosis

1- Microscopic examination

- Skin scales, nail & hair are examined microscopically after digesting using

10% KOH.

- Hyphae or spores are detected in the hair.

- Spores are detected either inside the hair (endothrix) or outside the hair

(ectothrix)

Hair examination

- Shaft → ectothrix

- bulb → endothrix

2- Culture

- Cultured in Sabouraud’s dextrose agar SDA and incubated at room

temperature for 4 weeks.

- The arising colonies are examined microscopically after staining with

lactophenol cotton blue stain.

Always REMEMBER

The medium → SDA.

The stain → Lactophenol cotton blue stain.

Treatment

- Local antifungal cream (miconazole).

- Keep the infected area dry; moisture helps these fungi to grow.

- Nail infections need a long treatment through Oral Administration of

“Terbinafine” for 3-6 months (difficult to treat).

Microsporum, Trichophyton & Epidermophyton Species

- Special traits

Microsporum: Thick Wall, spindle shape, multicellular.

Trichophyton: Thin Wall, pencil-shaped, large, smooth appearance with

septums.

Epidermophyton floccosum: Bifurcated hyphae with multiple, smooth,

club shaped macroconidia (2-4 cells)

Candidiasis

Candida albicans is the most important and most common species of candida.

Candida albicans is an oval gram-positive budding (way of replication) yeast

which produces pseudo-hyphae (species include: C. glabrata and C. krusei).

It colonizes the mucous membranes of the upper respiratory tract, GIT &

female genital tracts. (Normal flora in 3% of the people)

• It usually causes superficial infections on the skin and mucous membranes.

• It may predominate and spread towards the systems in

immunocompromised patients.

Predisposing factors to Candida infections

• Patients with AIDS & diabetes mellitus.

• Drugs: prolonged treatment with broad spectrum antibiotics &

corticosteroids.

• General disability.

• Indwelling urinary catheters.

Thus, it is called → the opportunistic fungi.

Pathogenesis & Symptomatology

1- Skin invasion

➢ They are red & weeping lesions, like ulcers.

➢ Mainly affect warm moist areas; axilla, intergluteal folds or infra mammary

folds (or any other fold).

➢ Mostly in obese & diabetic patients.

➢ Pseudo-diaper rash for the baby. Usually misdiagnosed as a bacterial

infection, impetigo, Fucidin won’t show any effect, the condition remains

there until the right treatment is given (local azoles).

2- Mouth infection

C. albicans produces white patches in the mouth, like the mucous membrane

(oral thrush or moniliasis).

3- Vulvovaginitis

- Usually in pregnant women; due to hormonal changes.

- Usually with itching & thick vaginal discharge.

- Common with diabetic woman & prolonged use of antibiotics.

- IUCD (intrauterine device), contraceptive method.

4- Nail infection

Thick, yellow, weak and can easily be removed from its place.

5- Systemic candidiasis

In immunocompromised.

Diagnosis

Direct Microscopic Examination

Specimens from skin, vaginal discharge or exudates from mucous surfaces are

examined or you can even examine the blood if you suspect a candidemia

and you should see oval gram positive budding yeast celsl with pseudo-

hyphae.

Culture

Can be grown on nutrient agar, corn meal agar & SDA (Sabouraud’s dextrose

agar SDA)

Identified by

1- Morphology

Oval budding gram positive yeast cells.

2- Differentiation tests

a. Germ tube test: germ tubes are

formed when colonies are incubated

with human serum at 37 C for 30

min.

b. Chlamydospore formation on corn

meal agar.

c. Biochemical reactions: C. albicans ferments glucose & maltose with acid &

gas production.

Treatment differs according to the site of infection

- Oropharyngeal or esophageal thrush → local treatment: Nystatin

Fluconazole ointment.

- Skin lesions → local treatment: Nystatin ointment.

- Systemic candidiasis → you have to use a systemic treatment (Caspofungin

IV, Ketoconazole (orally) Amphotericin B (IV) )

Subcutaneous Mycosis

Mycetoma (Madura foot): Mycetoma is a chronic infection of skin and

subcutaneous tissues.

- These infections are caused by fungi that grow in soil & on decaying

vegetations.

- The fungi are introduced into the subcutaneous tissues through trauma.

Pathogenesis: granulomatous lesions due to proliferation and body response.

The disease usually affects farmers.

Diseases

1- Eumycetoma: caused by the fungi Madurella mycetomatis, this is

characterized by having true septate hyphae.

2- Actinomycetoma: it is a bacterial infection, rare & caused by species of

actinomycetes. The symptoms are close to those of eumycetoma.

(Filamentous aerobic bacteria).

Clinically

Swelling following trauma, purplish discoloration & multiple sinuses that

drain pus containing yellow, white, red or black granules or black discharge.

Note: Disfigurement of the organ might also occur due to the granulomas.

E.g. Madura foot.

Diagnosis

Macroscopic examination

Depend on the color of the granules → Black granules are common with

fungal infections (sinuses with pus are also noted).

Microscopic examination

- Septate hyphae with spores in fungal infection.

Culture: on SDA

Treatment

1.Medical: • - ketoconazole • - Itraconazole • - Amphotericin B

2. Surgical intervention.

Cryptococcus Neoformans

Cryptococcus neoformans causes cryptococcosis.

• A widespread encapsulated yeast that inhabits soil around pigeon roosts.

• Commonly infects patients with AIDS, cancer or diabetes

(immunocompromised patients) → opportunistic infection.

• it starts by infecting the lungs by inhalation from the environment; it leads to

cough, fever, and lung nodules → fungal pneumonia.

• Dissemination to meninges and brain can cause severe neurological

disturbance and death.

Diagnosis

- Microscopic

India ink for capsule stain, special stain (50-80% + CSF) (you need to order this

stain specifically, it is not a common test).

- Culture

Bird seed agar – Routine blood culture

- PCR

Aspergillosis

Diseases of the Genus Aspergillus

➢ Very common airborne soil fungus.

➢ 600 species, 8 involved in human diseases; caused mainly by A. fumigatus.

➢ Serious opportunistic threat to AIDS, leukemia, and transplant patients →

the spores are present in the environment; only immunocompromised

patients are affected.

Note: immunocompetent individuals will have an asymptomatic infection and

the body will soon terminate the infection OR they may develop

Bronchopulmonary allergy, asthma or even exacerbation of asthma in

already asthmatic patients.

• The infection usually occurs in the lungs, spores germinate in the lungs and

form fungal balls; can colonize sinuses, ear canals, eyelids, and conjunctiva.

• Bronchopulmonary allergy (in immunocompetent) or Invasive aspergillosis

(in immunocompromised) usually affect preformed cavities in lungs due to

previous infection of TB or abscess, these fungi replicate within these

cavities producing cotton like spheres which can cause a necrotic

pneumonia, infection of the brain, the heart, and other organs (difficult to

treat).

Treatment

• Surgery, Amphotericin B and nystatin.

Zygomycosis

- Usually in uncontrolled diabetic patients.

- Opportunistic.

- 3 involved genera; Rhizopus, Absidia, and Mucor.

- Very invasive, invade the mucous membrane of the nose → to the

cerebra, if it reaches the brain it is usually fatal as it causes massive

destruction to the tissue (poor prognosis).

- Usually harmless air contaminants. They invade the membranes of the

nose, eyes, heart and brain of the people (Rhinocerebral mucormycosis)

with diabetes and malnutrition with severe consequences.

Rhinocerebral mucormycosis is a rare opportunistic infection of the sinuses, nasal

passages, oral cavity and the brain caused by saprophytic fungi.

Diagnosis

Made by direct smear and by isolation of molds from respiratory secretions

or biopsy specimens.

Treatment

Control Diabetes, surgery & amphotericin B

Prognosis

Very poor

Classical Case

Diabetic patient with nose lesions & meningitis most likely it is zygomycosis.