Fungus

Candida Species

Epidemiology
Most common fungal pathogen
4th most common nosocomial infection
75% of women may become infected at least once in their lifetime
Common infection in patients with AIDS , cancer ( ex:-leukemia)
Most common fungus affecting immunecompromised

Mycology

Yeast like fungus
There are 6 species that infect man
C. tropicalis, C. glabrata, C. parapsilosis, C.kusei, & C. lusitaniae
The most common species is Candida albicans
Found in mouth , vagina and intestinal tract in small colonies suppressed by immune system and other flora

Candida albicans

Morphology

solitary, unicellular
reproduction via budding
rounded shape
moist & mucous colonies

Pathogenesis

Surface molecules that permit adherence of the organism to other structures (eg, human cells, extracellular matrix, prosthetic devices)
Acid proteases and phospholipases that involve penetration and damage of cell envelopes
Ability to convert to a hyphal form (phenotypic switching)

Virulence assay of different C. albicans

strains using the skin equivalent

Figure 1. skin equivalent before infection

Figure 2. Infection with pathogenic clinical isolate of C. albicans.

After 48 h the yeast penetrates the skin equivalent and destroys
the tissue




Figure 3. Infection with non-pathogenic C. albicans. This strain is not able to penetrate into the tissue and thus behaves as a virulent as shown in the mouse model of systemic infection


How Does It Cause Disease ?Effects on immune system
Disturb immune system
Stimulate the body to form autoantibodies
Induce endocrinopathies
IgA protease
Contain glycoproteins that stimulate mast cells to release histamine and prostaglandins

How Does It Cause Disease Effects of its growth

It assimilates all sugars except lactose.
It depresses the activity of lactase.
Dietary carbohydrates are fungal growth promoters and associated with increased adherence of Candida species to mucosal epithelial cells.
Release of toxic fungal metabolites.

Risk Factors of Infection

Physiological:- Pregnancy, age (elderly & infants) ,Diet high in sweets, fruit juices, alcohol

Trauma:- Infection, burn wounds.

Haematological:- Neutropenia, cellular immunodeficiency (leukemia, lymphoma, AIDS, aplastic (anemia

Risk Factors of Infection

Endocrinological:- Diabetes mellitus, Addison’s disease, hypoparathyroidism


Iatrogenic:- Chemotherapeutics, corticosteroids, oral contraceptives, antibiotics catheters, surgery

Others:-Intravenous drugs, malnutrition, malabsorption, Chronic Stress

Diseases by C. albicans

Thrush
Esophagitis
Cutaneous candidiasis
Genital candidiasis
Deep candidiasis
Note:- Esophagitis and Deep Candidiasis occur only in immuncompromised patients

Thrush

Common in infants (Considered normal unless it lasts longer than a couple of weeks.)
Diabetics are more likely to get oral thrush because the extra sugar in their saliva acts like food for Candida.
High antibiotics doses or prolonged use increases the risk of oral thrush. Antibiotics kill some of the healthy bacteria that help keep Candida from growing too much.
Poorly fitting dentures are increases the risk of thrush.
Common in immunocompromised hosts,such as those with HIV infection.

Oral thrush

multiple white plaques on lips, gingivae, tongue, and palate
Thrush appears as whitish, velvety lesions in the mouth and on the tongue. Underneath the whitish material, there is red tissue that may bleed easily. The lesions can slowly increase in number and size.

Oropharyngeal ThrushFeatures

Pseudo membranous

Oropharyngeal ThrushFeatures

Atrophy of tongue

Oropharyngeal ThrushFeatures

Angular chelitis

Candida Esophagitis

Cutaneous Candidiasis

This child has a large rash caused by Candidiasis, affecting the skin around the mouth. There are also other lesions that aren't connected to the large lesion, called "satellite lesions".


Vulvovaginal Candidiasis (VVC)
Vulvar component often dominant
Women are often misdiagnosed as having VVC when they really have
- Genital herpes - Contact dermatitis
- Lichen planus - Atrophic vaginitis
- Recurrent BV (Bacterial Vaginosis)

Vulvovaginal Candidiasis

Deep CandidiasisFour forms of invasive candidiasis

Catheter related candidemia
Acute disseminated candidiasis
Chronic disseminated candidiasis
Deep organ candidiasis

Candidemia

Onchomycosis

Nail infections are much more difficult to
cure and can last a lifetime without proper
treatment


Candidemia

Hematogenous seeding

Spread to the eye Can cause blindness

Laboratory diagnosis

Specimen

Scrapings of surfaces

Laboratory diagnosis

Slide preparations

Visualization of pseudohyphae (mycelia) and/or budding yeast (conidia)

KOH or saline

Laboratory diagnosis


Staining

Lacto phenol blue

Gomoris methylamine sliver stains
(GMS)

Laboratory diagnosis

Culture

Sabourauds glucose agar medium

Brain heart infusion.

Laboratory diagnosis

Serology

CFT

Latex agglutination
ELISA
Fluorescent Abs


Laboratory diagnosis

Other Diagnostic

Methods

Skin test

PCR

Candida culture

Immunofluorescence

Treatment of Candida albicans

Dietary :-
Eliminate all sugar:
–fruit juice
–white flour
–refined grains


Eat a higher protein, lower carbohydrate and high fiber diet.

Avoid fermented foods including alcohol.

Treatment of Candida albicans
Antifungal drugs:-
Amphotericin B (Fungizone)
Clotrimazole (Mycelex)
Fluconazole (Diflucan)
Itraconazole (Sporanox)
Ketoconazole (Nizoral)
Nystatin (Mycostatin)