candida lab

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Candida
The colonies of Candida spp are cream colored to yellowish , grow rapidly and mature in 3- days the texture of the colony smooth , glistening or dry , wrinkled depending on the species on Sabroudaus agar .
Identification
Microscopic Examination
A portion of colonies removed from the culture and placed on a slide with lacto phenol cotton blue or gram stain and tested under the light microscope.
Germ tube production
This test was carried out by suspending a very small inoculums of yeast obtained from an isolated colony in 0.5 ml of human serum , incubated at 35C0 to 37 C0 for 2-3 hours .After incubation, a drop of the suspension is removed and placed on a microscopic slide , examined under low power magnification for the presence of germ tube .
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Dalmau plate Technique
A flamed sterilized straight wire was clipped into the surface of a corn meal with agar plate .The plates were incubated at 25 C0 for up to 3-5 days and examined using high power of the microscopic for the presence of peudohyphae and chlamydospore .
Surface Growth
This test was carried out by adding a drop of the inoculums pool suspension into a standard test tube approximately half filled with SDB or an equivalent medium , incubated for 48 hours at 30 C0. The result of the test was recorded by the presence of growth at the surface of the medium with or without air bubbles .
Urease Test
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This test was carried out by inoculating a urea medium with a loop full of the yeast isolate , incubated at 30 C0 for 72 hour .The change of the medium color into pink is indicated a positive result .
Growth at 45Co
This test was used for differentiating Candida albicans from other species . Candida isolates were used to inoculate test tubes containing SDB and then incubated at 42Co- 45Co for 48 – 72 hours .After incubation , Candida albicans showed grow well at this temperature , while other species give poor or no growth .
Sugar Fermentation Test
This test included sugars , Glucose , Sucrose , Maltose , Galagtose, Mannitol and lactose in stocks of 2% final concentration, sterilized by filtration using filters with 0.22 ?m pores diameter . One ml of sugar stock solution was added to 2 ml fermentation broth . A volume of 0.1 ml inoculated into each of sugar test tube , incubated at 30 C for 2- 3 day , with daily shacking . The color change , from pink to yellow is indicated of positive result , with or without gas formation as detected in Durham tube inserted in the medium tube .
API Candida Diagnostic strips
To confirm the identification of clinical isolates , Rapid ID Yeast Plus System was performed according to the instruction of manufacturer .The individual reactions were determined by numerical values and were assigned to the positive and negative tests.
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