CANDIDA Species

CANDIDA Sp

Candida sp belongs to yeast. There are medically eight important species of candida which can cause infection in humans.They are :

Candida albicans

Candida stellatoidea

Candida tropicalis

Candida krusei

Candida guilliermondii

Candida glabrata

Candida parapsilosis

Out of these eight species of candida, candida Albicans is responsible for the most of the human infections( greater than 90%)

Candida albicans is an opportunistic pathogen that fails to induce disease in most immunocompetent persons but can do so in those with impaired host defense as in AIDS patients ,patients undergoing prolonged antibiotic therapy or in patients with invasive surgery. It is part of normal flora of mucous membrane of the upper respiratory tract (URT),gastrointestinal (GI) tract .

Morphology of C.albicans:

Candida albicans is a small,oval yeast measuring 2-4 µm in diameter .In tissues,it may appear as yeast ,budding yeast,or pseudohyphae .Pseudohyphae are elongated yeast cells that visually resemble hyphae ,but not the true hyphae i.e. elongated yeast cells joined end to end resembling that of hyphae.

Virulence factors and pathogenesis :

The pathogenesis of candida infection is extremely complex. However, adherence of candida to the epithelium of the gastrointestinal tract or genital tract is critically important .Candida sp commonly colonizes the mucosal surface and their ability to invade and cause infection is first dependent on a binding .Fibronectira a component of host extracellular matrix also play a role in the initiation and dissemination of candida infection.

Besides that ,3 distinct aspartyl-protease have been found in these yeast cells that play a major role in causing infection .Different hydrophobic molecule present on the surface of yeast cells also appear to be important in pathogenesis,as there is a strong co-relation between adhesion and surface hydrophobicity. Similarly , not least important is the immune-suppressive activity of yeast mannans that may contribute to the virulence of these yeasts.

Disease caused by C.albicans :

Disease caused by c.albicans is commonly called candidosis may be superficial or systemic :

i)Superficial candidosis : The superficial forms of candidosis is usually an opportunistic endogenous infection. It may occur at different sites.

*Candidosis at mucous membrane :

Overgrowth of c.albicans in mouth produces white patches called ‘thrust’ which occurs most frequently in infants and old aged people .The thrust is usually the pseudomembrane formed on the mucous membrane.The ‘thrust’ may appear on the mucous membrane of the female genital tract which appears with the symptoms like itching and discharge and especially seen in patients with diabetes or patient’s undergoing prolonged antibiotic therapy.

Candidosis of skin :

Infection of the skin usually occurs in sites that may become abnormally moist and warm such as axillae,groin, toe cleft, etc.

Candidosis of nail :

Fingers and nail become involved when repeatedly immersed in water. For example : in person’s employed as a dishwasher in restaurants and institutions. Infections are characterized by thickening and reddening at the injection site.

ii)Systemic candidosis(infection) :