candida albicans

Candida albicans

Mycology
Is the science that study fungi and their structures reproduction ,cultivation ,diagnosis, and diseases.


1- Fungi unlike bacteria are eukaryotic. 2- Non motile . (but spores are motile ). 3- Reproduction by :- A- sexually ( meiosis ) B- asexually ( budding ) 4- All fungi are aerobic and most are grow in simple media with acidic pH.
Characteristics of fungi:


Hyphae singular hypha or hyphum are thread like tubes containing the fungal cytoplasm and its organelles , separated by cross wall (septa)which divide the hyphae ,the septa have pores that allow the movement of cytoplasm ,they can be considered as the structural units of the mould.

Mycelium (mass of hyphae that form the mould colony Pseudo mycelium of Candida.albicans appear under semi anaerobic conditions and consist of elongated cells that may remain end to end in chain, especially at lower incubation temperatures or poor nutrient in medium.

Blastospores Is the simple budding forms by budding the daughter cell from the mother cell .

Classification of fungi

1-Yeast unicellular with spherical or ovoid bodies ,all yeast are similar morphologically on light microscopic examination. Yeast are identified by biochemical reactions based on the fermentation and assimilation of carbohydrates utilization of enzymes and other metabolic activities.


classification
2-Moulds multicellular form have filaments thus forming multicelular type of structure ,moulds are identified by their colour ,texture and colonial and microscopic examination.

classification

3-Dimorphic fungi. exist as mould in the natural environment (and laboratory culture ) and as yeasts in tissue.

Candida Spp. The most important species in the fungi is Candida Spp. especially Candida albicans which cause 90% of diseases in human body. Found as normal flora of Oral cavity. Upper respiratory tract. Gastrointestinal tract. Female genital tract.


Species of Candida: C. albicans. C. tropicalis. C. krusei. C. parakrusei. C. dubliniensis.


Pathogenicity:- Oral thrush. Denture stomatitis . Root canal infection . Nail and skin infection . Vagina candidiasis . Endocarditis . Meningitis .


-Candida albicans is a dimorphic fungus ,it can take two forms ,most of time it exist as oval ,single yeast cells which reproduce by budding, but under physiological conditions it may develop in to hyphal form.

LAB. Diagnosis Staining: gram positive. Under microscope examination: Oval unicellular. Large cells.


Candida albicans and C.dubliniens is may be differentiated from Candida species by their ability to produce germ tubes and chlamydospore.



1-Germ tubes production : Procedure : Grow the yeast in peptone water . Transferring few drops to 0.5 ml of serum . Incubate at 37C for 4 hour in water bath . Examined each half of hour under microscope to observe the germ tube.

Germ tube formation

2- Chlamydospores :-Is the large , thick , walled resting spores , which produce by the enlarging of the terminal cell of the hyphae. when incubated at 22 _25Ċ with decreased O2 on an nutritionally poor medium(corn meal agar).

*Chlamydospore production: a-Touch a yeast colony and streak on corn meal agar. b- Incubate at room temp.for 48hr. c- Examine under microscope.

Blastospore and Chlaymdospore of C. albicanis

Differential diagnosis of candida species
Lactose
Sucrose
Maltose
Glucose
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+
+
+
C. albicans
-
+
+
+
C. tropicalis
-
+
-
+
C.pseudotropicalis
-
-
-
+
C. krusei
-
-
+
+
C. dubliniensis



The number of Candida species increase in certain condition : Diabetes. Cancer therapy. AIDS. Patients who received broad spectrum of antibiotics. Pregnancy.

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